A Thermochromic, Viscoelastic Nacre-like Nanocomposite for the Smart Thermal Management of Planar Electronics

Cutting-edge heat spreaders for soft and planar electronics require not only high thermal conductivity and a certain degree of flexibility but also remarkable self-adhesion without thermal interface materials, elasticity, arbitrary elongation along with soft devices, and smart properties involving thermal self-healing, thermochromism and so on. Nacre-like composites with excellent in-plane heat dissipation are ideal as heat spreaders for thin and planar electronics. However, the intrinsically poor viscoelasticity, i.e., adhesion and elasticity, prevents them from simultaneous self-adhesion and arbitrary elongation along with current flexible devices as well as incurring high interfacial thermal impedance. In this paper, we propose a soft thermochromic composite(STC) membrane with a layered structure, considerable stretchability, high in-plane thermal conductivity(~30 Wm^(-1) K^(-1)), low thermal contact resistance(~12 mm^2 KW^(-1), 4–5 times lower than that of silver paste), strong yet sustainable adhesion forces(~4607 Jm^(-2), 2220 Jm^(-2) greater than that of epoxy paste) and self-healing efficiency. As a self-adhesive heat spreader, it implements efficient cooling of various soft electronics with a temperature drop of 20℃ than the polyimide case. In addition to its self-healing function, the chameleon-like behavior of STC facilitates temperature monitoring by the naked eye, hence enabling smart thermal management.

Functional porous materials for blood purification

Blood purification,particularly for renal disease therapy,involves hemodialysis,hemofiltration,hemoperfusion,plasma exchange and immunoadsorption,etc.It is a process which extracts the patient’s blood,followed by passing it through a purification device to remove some toxinic molecules.Among various types of hemopurification means,the physical/chemical adsorption mediated toxins clearance method is the most generalized.Functional porous materials with well-elaborated porosity,considerable surface area,and specific surface groups are critical as adsorbents.The past decades have witnessed some promising applications in water treatment,gas separation and catalytic reaction.However,when referring to the domain of blood purification,merely large adsorption capacity is not competent for adsorbents.

肺癌患者恶病质的药物治疗与营养支持研究进展

恶病质是肺癌患者的一种常见并发症,它会加重化疗毒副作用、阻碍治疗计划、削弱化疗反应性、降低生活质量,增加并发症及死亡率,严重危害肺癌患者的生理、心理健康。肿瘤恶病质的发病原因与发病机制都极为复杂,使其治疗具有艰巨性与复杂性。控制肺癌患者的恶病质需要采取抗肿瘤治疗、抑制炎症反应、营养支持、体育锻炼、缓解症状等多种手段,发挥多模式治疗的协同作用对抗肿瘤恶病质的多种机制。迄今为止,学科内已就任何单一疗法都不能控制恶病质的发生发展达成了一致共识。有些疗法取得了一定的研究进展,但需要在充分评估肺癌患者个体特征后结合多模式治疗实施。本文重点综述了肿瘤恶病质的药物治疗与营养支持等干预方法在肺癌患者人群中的应用,并对肺癌患者恶病质控制的研究方向进行展望。

DERL3影响肺腺癌细胞A549增殖、侵袭转移的机制

背景与目的内质网蛋白降解3(Derlin 3,DERL3)的表达水平与结直肠癌患者的淋巴转移与远处转移密切相关,然而其在肺腺癌中的表达和生物学行为研究甚少。本研究旨在探讨DERL3在肺腺癌组织中的异位表达及其对肺腺癌A549细胞系侵袭转移的影响,以揭示其影响肺腺癌侵袭转移的可能机制。方法肺腺癌微阵列基因芯片分析有无淋巴结转移肺腺癌组织各3例。GEDS与Kaplan-Meier plot查询DERL3在癌症中表达情况与生存曲线。采用Western blot检测细胞中DERL3表达与质粒转染效率。敲低DERL3基因后,采用Transwell检测肺腺癌细胞穿过小室基底膜的数量。采用5-乙炔基-2′脱氧尿嘧啶核苷(EDU)检测细胞增殖能力。采用Western blot方法检测与上皮间质转化相关的E-钙黏蛋白(E-cadherin)和波形蛋白(Vimentin)的表达情况。结果微阵列基因芯片结果显示有淋巴结转移的肺腺癌组织中总共有400个表达下调的mRNAs、1,314个上调的mRNAs。DERL3在肺腺癌组织中明显上调(P<0.05)。生存曲线结果显示DERL3高表达肺癌患者的预后差(P<0.05)。Western blot结果提示质粒敲除成功。敲低DERL3后细胞增殖、迁移与侵袭能力受到抑制(P<0.05)。敲低DERL3后,Vimentin表达水平下降,E-cadherin表达上升(P<0.05)。结论敲低DERL3基因可抑制A549细胞系的增殖、侵袭与转移能力。

Estimation of ground heat flux and its impact on the surface energy budget for a semi-arid grassland

Three approaches, i.e., the harmonic analysis （HA） technique, the thermal diffusion equation and correction （TDEC） method, and the calorimetric method used to estimate ground heat flux, are evaluated by using observations from the Semi-Arid Climate and Environment Observatory of Lanzhou University （SACOL） in July, 2008. The calorimetric method, which involves soil heat flux measurement with an HFP01SC self-calibrating heat flux plate buried at a depth of 5 cm and heat storage in the soil between the plate and the surface, is here called the ITHP approach. The results show good linear relationships between the soil heat fluxes measured with the HFP01SC heat flux plate and those calculated with the HA technique and the TDEC method, respectively, at a depth of 5 cm. The soil heat fluxes calculated with the latter two methods well follow the phase measured with the HFP01SC heat flux plate. The magnitudes of the soil heat flux calculated with the HA technique and the TDEC method are close to each other, and they are about 2 percent and 6 percent larger than the measured soil heat flux, respectively, which mainly occur during the nighttime. Moreover, the ground heat fluxes calculated with the TDEC method and the HA technique are highly correlated with each other （R2= 0.97）, and their difference is only about 1 percent. The TDEC-calculated ground heat flux also has a good linear relationship with the ITttP-calculated ground heat flux （R2 = 0.99）, but their difference is larger （about 9 percent）. Furthermore, compared to the HFP01SC direct measurements at a depth of 5 cm, the ground heat flux calculated with the HA technique, the TDEC method, and the ITHP approach can improve the surface energy budget closure by about 6 percent, 7 percent, and 6 percent at SACOL site, respectively. Therefore, the contribution of ground heat flux to the surface energy budget is very important for the semi-arid grassland over the Loess Plateau in China. Using turbulent heat fluxes with common corrections, soil heat storage between the surface and the heat flux plate can improve the surface energy budget closure by about 6 to 7 percent, resulting in a closure of 82 to 83 percent at the SACOL site.

Aqueous high-voltage all 3D-printed micro-supercapacitors with ultrahigh areal capacitance and energy density

With the rapid development of integrated and miniaturized electronics,the planar energy storage devices with high capacitance and energy density are in enormous demand.Hence,the advanced manufacture and fast fabrication of microscale planar energy units are of great significance.Herein,we develop aqueous planar micro-supercapacitors(MSCs) with ultrahigh areal capacitance and energy density via an efficient all-3 D-printing strategy,which can directly extrude the active material ink and gel electrolyte onto the substrate to prepare electrochemical energy storage devices.Both the printed active carbon/exfoliated graphene(AC/EG) electrode ink and electrolyte gel are highly processable with outstanding conductivity(~97 S cm^(-1) of electrode;-34.8 mS cm^(-1) of electrolyte),thus benefiting the corresponding shaping and electrochemical performances.Furthermore,the 3 D-printed symmetric MSCs can be operated stably at a high voltage up to 2.0 V in water-in-salt gel electrolyte,displaying ultrahigh areal capacitance of2381 mF cm^(-2) and exceptional energy density of 331 μWh cm^(-2),superior to previous printed micro energy units.In addition,we can further tailor the integrated 3 D-printed MSCs in parallel and series with various voltage and current outputs,enabling metal-free interconnection.Therefore,our all-3 D-printed MSCs place a great potential in developing high-power micro-electronics fabrication and integration.

Two-dimensional Boron Nitride for Electronics and Energy Applications

Two-dimensional(2D)boron nitride(BN),the so-called“white graphene,”has demonstrated a great potential in various fields,particularly in electronics and energy,by utilizing its wide bandgap(~5.5 eV),superior thermal stability,high thermal conductance,chemical inertness,and outstanding dielectric properties.However,to further optimize the performances from the view of structure-property relationship,the determinative factors such as crystallite sizes,layer thickness,dispersibility,and surface functionalities should be precisely controlled and adjusted.Therefore,in this review,the synthesis and functionalization methods including“top-down”and“bottom-up”strategies,and non-covalent and covalent modifications for 2D BN are systematically classified and discussed at first,thus catering for the requirements of versatile applications.Then,the progresses of 2D BN applied in the fields of microelectronics such as fieldeffect transistors and dielectric capacitors,energy domains such as thermal energy management and conversion,and batteries and supercapacitors are summarized to highlight the importance of 2D BN.Notably,these contents not only contain the state-of-the-art 2D BN composites,but also bring the current novel design of 2D BN-based microelectronic units.Finally,the challenges and perspectives are proposed to better broaden the scope of this material.Therefore,this review will pave an all-around way for understanding,utilizing,and applying 2D BN in future electronics and energy applications.

Discussion on Ecological Ethics Implication of Youyu Spirit

Ecological ethics is a kind of ethics code adjusting relationship between human and nature. Ecological ethics implication of Youyu spirit reflects in four aspects： eco-value concept of ＂nature and human unifying, revering nature＂, eco-politics concept of ＂persisting greening, diligently working for people＂, eco-obligation concept of ＂predecessor planting, descendant cooling＂ and eco-culture concept of ＂public participation, harmonious development＂. It has important value for constructing beautiful Shanxi and realizing ecological civilization to excavate and carry forward ecological ethics implication of Youyu spirit.

Hydrolysis mechanism of YbB_(2)C_(2)and the microstructure of the carbon derived from the hydrolysis reaction

Carbide-derived carbon(CDC)materials have gained great attention due to the excellent properties for various potential applications.Here,graphite crystal is formed during a room-temperature hydrolysis pro-cess of layered compound YbB_(2)C_(2).The formation mechanism can be demonstrated by a YbB_(2)C_(2)molecular cell:Yb^(3+)acts as a cathode where H_(2)O molecule is reduced to H atom and OH^(−)ion,while(B_(2)C_(2))^(3−)acts as an anode where OH−ion is oxidized to O atom.Then,YbB_(2)C_(2)molecular cell begins to disintegrate,i.e.,Yb^(3+)ion,B and C atoms dissociate from the molecular cell.The as-produced C atoms combine to form graphite crystal.The initial graphite crystal is a cabbage-like microsphere,and then it gradually disintegrates and transforms into layered graphite.In addition,YbB_(6),Yb_(3)(OH)_(3)n(BO_(3))_((3-n))sol,hydrogen,hydrocarbons,and carbon oxides form simultaneously.Our method provides a general and inexpensive route to obtain carbide-derived graphite crystal.

流固耦合对微尺度下气体扩散层液态水流动的影响

提出了一种重构碳纤维气体扩散层(GDL)微观结构的新方法,用于研究粗糙孔隙通道内速度场对GDL渗流量的影响。利用粗糙元和分形理论得到GDL内部孔隙通道随机分布模型,通过区分通道壁面亲/疏水性,得出了弥散速度占比、滑移增强系数、黏性增强系数和微尺度效应增强系数四种参数,并以此作为控制因素重构更加准确的内部速度分布,结合Darcy定律得到有效渗流系数模型。对GDL孔隙通道内部液态水的流动过程进行模拟,分析了不同粗糙度和接触角对液态水传输性能的影响。研究结果表明,孔隙通道粗糙元随机分布和不均匀流固耦合作用影响扩散层内部弥散速度、黏性、滑移速度的分布,四种控制因素共同作用于液态水的流动过程并促进液态水排出;相同粗糙度情况下,接触角为0o~180o时,亲水壁面滑移效应的促进作用大于弥散效应和黏性的抑制作用的程度逐渐增加,疏水壁面滑移效应的促进作用大于弥散效应和黏性的抑制作用的程度逐渐减小,流量变化曲线的斜率先显著增加后逐渐减小。新建立的扩散层内部液态水有效渗流系数模型可准确描述GDL内部液态水的流动规律,对GDL内部水管理具有一定的指导意义。

Rapid CO_(2)-laser scribing fabrication of an electrochemical sensor for the direct detection of Pb^(2+) and Cd^(2+)

Laser-induced graphene(LIG)is a highly promising preparation material for electrochemical sensors;however,its preparation speed and nanomaterial modification steps significantly limit its mass production.Herein,this study proposed a new laser printing strategy that considerably improved the preparation speed of LIG with excellent electrochemical performance.Using the optimal parameters(laser power of 1%,scribing spacing of 0.12 mm,scribing speed of 100 mm·s^(−1)),it took only 14.2 s to complete the preparation of the detection electrode.Thus,we successfully detected Cd^(2+)and Pb^(2+)without any toxic reagents or electrode modification steps.The limits of detection of the sensor were 0.914 and 0.916μg·L^(−1)for Cd^(2+)and Pb^(2+),respectively,which are significantly lower than the required values for drinking-water quality,according to the World Health Organization guidelines.This study provides a novel approach for the rapid detection of heavy-metal ions.

A temperature prediction-correction method for estimating surface soil heat flux from soil temperature and moisture data

Surface soil heat flux is a component of surface energy budget and its estimation is needed in land-atmosphere interaction studies. This paper develops a new simple method to estimate soil heat flux from soil temperature and moisture observations. It gives soil temperature profile with the thermal diffusion equation and, then, adjusts the temperature profile with differences between observed and computed soil temperatures. The soil flux is obtained through integrating the soil temperature profile. Compared with previous methods, the new method does not require accurate thermal conductivity. Case studies based on observations, synthetic data, and sensitivity analyses show that the new method is preferable and the results obtained with it are not sensitive to the availability of temperature data in the topsoil. In addition, we pointed out that the soil heat flux measured with a heat-plate can be quite erroneous in magnitude though its phase is accurate.

Effect of Mesoscale Land Use Change on Characteristics of Convective Boundary Layer:Semi-Idealized Large Eddy Simulations over Northwest China

Although large-scale topography and land use have been properly considered in weather and climate models, the effect of mesoscale and microscale heterogeneous land use on convective boundary layer(CBL) has not been fully understood yet. In this study, the influence of semi-idealized strip-like patches of oases and deserts, which resemble irrigated land use in Northwest China, on the CBL characteristics, is investigated based on the Weather Research and Forecasting(WRF)-large eddy simulation(LES) driven by observed land surface data. The influences of soil water content in oases on aloft CBL flow structure, stability, turbulent kinetic energy(TKE), and vertical fluxes are carefully examined through a group of sensitivity experiments. The results show that secondary circulation(SC)/turbulent organized structures(TOS) is the strongest/weakest when soil water content in oases is close to saturation(e.g.,when the oases are irrigated). With the decrease of soil water content in oases(i.e., after irrigation), SC(TOS) becomes weak(strong) in the lower and middle CBL, the flux induced by SC and TOS becomes small(large), which has a dramatic impact on point measurement of eddy covariance(EC) fluxes. The flux induced by SC and TOS has little influence on EC sensible heat flux, but great influence on EC latent heat flux. Under this circumstance, the area averaged heat flux cannot be represented by point measurement of flux by the EC method, especially just after irrigation in oases. Comparison of imbalance ratio(i.e., contribution of SC and TOS to the total flux) reveals that increased soil moisture in oases leads to a larger imbalance ratio as well as enhanced surface heterogeneity. Moreover,we found that the soil layer configuration at different depths has a negligible impact on the CBL flux properties.

Tunable strength of SiCf/β-Yb_(2)Si_(2)O_(7) interface for different requirements in SiCf/SiC CMC:Inspiration from model composite investigation

Model composites consisting of Si C fiber embedded inβ-Yb_(2)Si_(2)O_(7) matrix were processed by Spark Plasma Sintering method and the feasibility of tunable Si Cf/Yb_(2)Si_(2)O_(7) interface in Si C-based CMCs were estimated.Weak and strengthened Si Cf/Yb_(2)Si_(2)O_(7) interfaces were achieved by adjusting sintering temperatures.The indentation crack test and fiber push out experiments clearly demonstrated the different debonding mechanisms in the samples.Weak interfaces sintered at 1200 and 1250℃exhibited crack deflection at interface in indentation test.Their low debond energy at the interface,which were comparable to those of Py C or BN,satisfied the well-recognized interfacial debond and crack deflection criteria for CMCs.The interface was strengthened by atomic bonding in model composite sintered at 1450℃,leading to crack penetrating into Si C fiber and high debond energy.The strong interface may be promising in Si Cf/Si C CMC to withstand higher combustion temperature,because Yb_(2)Si_(2)O_(7) will provide plastic deformation capacity,which would serve as weak interphase for crack deflection and energy dissipation.Therefore,it is possible to design the capability of Si C_(f)/RE_(2)Si_(2)O_(7) interface for different requirements by adjusting interfacial strength or debond energy to reach optimal mechanical fuse mechanism in SiC_(f)/SiC CMC.

MXene coupled with molybdenum dioxide nanoparticles as 2D-0D pseudocapacitive electrode for high performance flexible asymmetric micro-supercapacitors

Recently,two-dimensional(2D)transition metal carbides and carbonitrides(MXenes),have shown great potential in micro-supercapacitors(MSCs).However,the maximum voltage output of symmetric MXene MSCs is limited to 0.6 V due to the oxidation effects at high anodic potentials.Herein,we developed asymmetric micro-supercapacitors(AMSCs)based on titanium carbide MXene(Ti_(3)C_(2)Tx)and MXene-MoO_(2) electrodes with an enlarged voltage window of 1.2 V,which is twice wider than that of symmetric MXene MSCs.The 2D-0D MXene-MoO_(2) microelectrode is fabricated by homogenous dispersing zerodimensional(0D)MoO_(2) nanoparticles into MXene layers to impede layers stacking and MoO_(2) nanoparticles aggregation.Notably,the AMSCs delivered good electrochemical performances of areal capacitance of ~19 mF cm^(-2) and volumetric capacitance of 63 F cm^(-3) at a scan rate of 2 mV s^(-1),and high energy density of 9.7 mW h cm^(-3) at a power density of 0.198 W cm^(-3).The AMSCs also presented exceptionally mechanical flexibility under different bending states and excellent cyclic stability,with 88% capacitance retention after 10000 cycles at a discharge current density of 0.5 mA cm^(-2).For practical application,the serially connected AMSCs are fully affordable to power electronics,which is beneficial for soft and wearable power devices.

Vertically aligned γ-Al00H nanosheets on Al foils as flexible and reusable substrates for NH3 adsorption

Vertically aligned γ-AlOOH nanosheets （NSs） have been successfully fabricated on flexible Al foils via a solvothermal route without morphology-directing agents. Three different reaction temperature （25, 80, and 120 ℃） and time （30 min, 45 min, and 24 h） are discussed for the growth period, which efficiently tune the density and size of theγ-AlOOH NSs. Meanwhile, the growth speed of the nanosheets confirms that dominant growth stage is seen in the initial 45 min. Furthermore, the interlayer of the γ-AlOOH NSs displays an average height of 140 nm and superhydrophilicity. By dynamic adsorption, the as- synthesized γ-AlOOH NSs exhibit an outstanding NH3 adsorption capacity of up to 146 mg/g and stably excellent regeneration for 5 cycles. The mechanism of NH3 adsorption on the in-plane of the γ-AlOOH NSs is explained by the Lewis acid/base theory. The H-bond interactions among the NH3 molecules and the edge groups （-OH） further improve the capture ability of the nanosheets.

Tunnel-structured willemite Zn_(2)SiO_(4):Electronic structure,elastic,and thermal properties

Willemite Zn_(2)SiO_(4)crystallizes in such a way that Zn and Si are tetrahedrally coordinated with O in an ionic–covalent manner to form ZnO_(4)and SiO_(4)tetrahedra as the building units.The tetrahedra are corner-sharing,of which one SiO_(4)tetrahedron connects eight ZnO_(4)tetrahedra,and one ZnO_(4)tetrahedron links four ZnO_(4)tetrahedra and four SiO_(4)tetrahedra.The unique crystallographic configuration gives rise to parallel tunnels with a diameter of 5.7Åalong the c-axis direction.The tunnel structure of Zn_(2)SiO_(4)definitely correlates with its interesting elastic and thermal properties.On the one hand,the elastic modulus,coefficient of thermal expansion(CTE),and thermal conductivity are low.Zn_(2)SiO_(4)has low Vickers hardness of 6.6 GPa at 10 N and low thermal conductivity of 2.34 W/(m·K)at 1073 K.On the other hand,the elastic modulus and CTE along the c-axis are significantly larger than those along the a-and b-axes,showing obvious elastic and thermal expansion anisotropy.Specifically,the Young’s modulus along the z direction(Ez=179 GPa)is almost twice those in the x and y directions(Ex=Ey=93 GPa).The high thermal expansion anisotropy is ascribed to the empty tunnels along the c-axis,which are capable of more accommodating the thermal expansion along the a-and b-axes.The striking properties of Zn_(2)SiO_(4)in elastic modulus,hardness,CTE,and thermal conductivity make it much useful in various fields of ceramics,such as low thermal expansion,thermal insulation,and machining tools.

Raman Spectroscopy of Layered Compound YbB_(2)C_(2)

REB_(2)C_(2)(RE=Y and lanthanides)compounds have gained attention for their unique layered crystal structure.However,there have been few reports about Raman spectroscopy of REB_(2)C_(2) compounds up to now.Here,the Raman spectrum of YbB_(2)C_(2) is obtained by a micro-Raman spectroscope and the first-principles calculations.Raman active vibrational modes of YbB_(2)C_(2) are confirmed as A_(1g)(627 and 1311 cm^(-1)),B_(1g)(944 and 1172 cm^(-1)),B_(2g)(330 and 885 cm^(-1))and E_(g)(357 and 530 cm^(-1)).Atomic displacements of these modes are different,they can be divided into two groups:A_(1g)’,B_(1g) and B_(2g) correspond to ring breathing(δ_(in),in the plane)of B_(2)C_(2) layer;E_(g) is due to ring deformation(δ_(oop),out of the plane)of B_(2)C_(2) layer.These results are helpful to understand the individual structure of REB_(2)C_(2).

Rare earth monosilicates as oxidation resistant interphase for SiCf/SiC CMC:Investigation of SiC_(f)/Yb_(2)SiO_(5)model composites

Model composites consisting of SiC fiber and Yb_(2)SiO_(5)were processed by the spark plasma sintering(SPS)method.The mechanical compatibility and chemical stability between Yb_(2)SiO_(5)and SiC fiber were studied to evaluate the potential application of Yb monosilicate as the interphase of silicon carbide fiber reinforced silicon carbide ceramic matrix composite(SiC_(f)/SiC CMC).Two kinds of interfaces,namely mechanical and chemical bonding interfaces,were achieved by adjusting sintering temperature.SiC_(f)/Yb_(2)SiO_(5)interfaces prepared at 1450 and 1500℃exhibit high interface strength and debond energy,which do not satisfy the crack deflection criteria based on He-Hutchison diagram.Raman spectrum analyzation indicates that the thermal expansion mismatch between Yb_(2)SiO_(5)and SiC contributes to high compressive thermal stress at interface,and leads to high interfacial parameters.Amorphous layer at interface in model composite sintered at 1550℃is related to the diffusion promoted by high temperature and DC electric filed during SPS.It is inspired that the interfacial parameters could be adjusted by introducing Yb_(2)Si_(2)O_(7)-Yb_(2)SiO_(5)interphase with controlled composition to optimize the mechanical fuse mechanism in SiC_(f)/SiC CMC.

Local high-temperature phenomena within magnetic clouds

In this study,three methods were used to analyze 17 large-scale local high-temperature regions with durations exceeding 2 h within magnetic clouds(MCs)observed by advanced composition explorer from 1998 to 2008.Results show that five of these large-scale regions may have been caused by flare heating;seven of the regions may have been caused by nonuniform expansion when MCs propagated in the solar-terrestrial space;four large-scale high temperature regions may likely result from combined non-uniform expansion and flare heating;and only one large-scale local high-temperature region was not related to either flare heating nor non-uniform expansion.No evidence indicated that magnetic reconnection occurred or had occurred within the high-temperature regions.Based on our results,we infer that such local high-temperature phenomena within MCs are caused primarily as a result of flare heating and non-uniform expansion,either separately or jointly,and that magnetic reconnection plays only a minor role in the formation of high-temperature regions.