Influence of substrate effect on near-field radiative modulator based on biaxial hyperbolic materials

Relative rotation between the emitter and receiver could effectively modulate the near-field radiative heat transfer(NFRHT)in anisotropic media.Due to the strong in-plane anisotropy,natural hyperbolic materials can be used to construct near-field radiative modulators with excellent modulation effects.However,in practical applications,natural hyperbolic materials need to be deposited on the substrate,and the influence of substrate on modulation effect has not been studied yet.In this work,we investigate the influence of substrate effect on near-field radiative modulator based onα-MoO_(3).The results show that compared to the situation without a substrate,the presence of both lossless and lossy substrate will reduce the modulation contrast(MC)for different film thicknesses.When the real or imaginary component of the substrate permittivity increases,the mismatch of hyperbolic phonon polaritons(HPPs)weakens,resulting in a reduction in MC.By reducing the real and imaginary components of substrate permittivity,the MC can be significantly improved,reaching 4.64 forε_(s)=3 at t=10 nm.This work indicates that choosing a substrate with a smaller permittivity helps to achieve a better modulation effect,and provides guidance for the application of natural hyperbolic materials in the near-field radiative modulator.

Near-field radiative heat transfer in hyperbolic materials

In the post-Moore era, as the energy consumption of micro-nano electronic devices rapidly increases, near-field radiative heat transfer(NFRHT) with super-Planckian phenomena has gradually shown great potential for applications in efficient and ultrafast thermal modulation and energy conversion. Recently, hyperbolic materials, an important class of anisotropic materials with hyperbolic isofrequency contours, have been intensively investigated. As an exotic optical platform, hyperbolic materials bring tremendous new opportunities for NFRHT from theoretical advances to experimental designs. To date, there have been considerable achievements in NFRHT for hyperbolic materials, which range from the establishment of different unprecedented heat transport phenomena to various potential applications. This review concisely introduces the basic physics of NFRHT for hyperbolic materials, lays out the theoretical methods to address NFRHT for hyperbolic materials, and highlights unique behaviors as realized in different hyperbolic materials and the resulting applications. Finally, key challenges and opportunities of the NFRHT for hyperbolic materials in terms of fundamental physics, experimental validations, and potential applications are outlined and discussed.

Pregnancy Loss in Relation to the Risks of Female-Specific Cancers in a Population-Based Cohort and Mendelian Randomization Study — China, 2004–2017

Summary What is already known about this topic?Limited evidence exists regarding the relationship between pregnancy loss and female-specific cancers within the Chinese population from prospective cohort studies.What is added by this report?Terminations were associated with a 13%lower risk of endometrial cancer,whereas stillbirths were related to an 18%higher risk of cervical cancer.Rural residents with a history of pregnancy loss experienced a 19%and 38%increased risk of breast and cervical cancers,respectively,compared to their urban counterparts.Moreover,a positive graded relationship between live births and pregnancy loss on cervical cancer was observed.What are the implications for public health practice?This study has significant implications for identifying women at an increased risk for breast and genital cancers and contributes to the development of effective public health strategies for female cancer prevention.Future research on reproductive history,particularly in rural areas,should be given priority in efforts to improve female cancer screening and early detection.

碗型NiCo2O4纳米片簇应用于高性能不对称超级电容器电极材料

开发具有可控结构的过渡金属氧化物基电极材料对于高性能超级电容器尤为重要,但这仍是其目前面临的重要挑战之一.本文通过一种简单的软模板水热策略,首次合成了碗型Ni Co2O4纳米片团簇.这种碗型团簇由19 nm厚的超薄Ni Co2O4纳米片层构成,单个团簇平均直径为1μm,材料比表面积达到40 m2g^-1.在三电极测试中,作为电极材料的碗型Ni Co2O4纳米片团簇在1 A g^-1的电流密度下表现出高比电容值(1068 F g^-1),且循环5000次后仍有90%的电容保有率.此外,以该Ni Co2O4团簇和活性炭作为电极材料组装而成的不对称超级电容器在1 A g^-1的电流密度下展示出129 F g^-1的比电容;在0.66 k W kg^-1功率密度下,能量密度高达33 W h kg^-1.这些性能优于大部分商业化的超级电容器.本研究为构筑面向能量储存和转换应用的结构可控的新型有序过渡金属氧化物材料开辟了新途径.