Rational design and synthesis of Cr_(1-x)Te/Ag_(2)Te composites for solid-state thermoelectromagnetic cooling near room temperature

Materials with both large magnetocaloric response and high thermoelectric performance are of vital importance for all-solid-state thermoelectromagnetic cooling.These two properties,however,hardly coexist in single phase materials except previously reported hexagonal Cr_(1-x)Te half metal where a relatively high magnetic entropy change(-△S_(M))of~2.4 J·kg^(-1)·K^(-1)@5 T and a moderate thermoelectric figure of merit(ZT)of~1.2×10^(-2)@300 K are simultaneously recorded.Herein we aim to increase the thermoelectric performance of Cr_(1-x)Te by compositing with semiconducting Ag_(2)Te.It is discovered that the in-situ synthesis of Cr_(1-x)Te/Ag_(2)Te composites by reacting their constitute elements above melting temperatures is unsuccessful because of strong phase competition.Specifically,at elevated temperatures(T>800 K),Cr_(1-x)Te has a much lower deformation energy than Ag_(2)Te and tends to become more Cr-deficient by capturing Te from Ag_(2)Te.Therefore,Ag is insufficiently reacted and as a metal it deteriorates ZT.We then rationalize the synthesis of Cr_(1-x)Te/Ag_(2)Te composites by ex-situ mix of the pre-prepared Cr_(1-x)Te and Ag_(2)Te binary compounds followed by densification at a low sintering temperature of 573 K under a pressure of 3.5 GPa.We show that by compositing with 7 mol%Ag_(2)Te,the Seebeck coefficient of Cr_(1-x)Te is largely increased while the lattice thermal conductivity is considerably reduced,leading to 72%improvement of ZT.By comparison,-△S_(M)is only slightly reduced by 10%in the composite.Our work demonstrates the potential of Cr_(1-x)Te/Ag_(2)Te composites for thermoelectromagnetic cooling.

A novel perylene diimide-based ionene polymer and its mixed cathode interlayer strategy for efficient and stable inverted perovskite solar cells

Inverted(p-i-n)perovskite solar cells(PerSCs)have attracted much attention owing to their low temperature processability,less hysteresis effect and easy integration as a subunit for the tandem device.The unsatisfactory interface contacts and energy level barrier between adjacent interlayers on the cathode side are one of the key challenges for the development of p-i-n PerSCs.Herein,perylene diimidebased(PDI)ionene polymer was synthesized and developed as a cathode interlayer(CIL)to enhance interface contact,reduce the energy level barrier and prevent the migration of I-ions.The compact PNPDI CIL with high conductivity and appropriate lowest unoccupied molecular orbital(LUMO)level,resulted in a high efficiency device(20.03%),which is higher than the control device with bathophenanthroline(Bphen)(19.48%).Bphen-based CIL shows better adjusting ability of the work function of cathode metal but exhibits poor film-forming property.So,the synergistic effect of 1+1>2 can be obtained by combining Bphen and PNPDI into one CIL.As expected,the device performance was further improved by using the mixed CIL of Bphen and PNPDI,and 21.46%power conversion efficiency(PCE)was achieved.What’s more,the compact and hydrophobic mixed CIL dramatically enhanced the resistance to I-ions and moisture,which led to much enhanced device stability.

Recent advances of Cu-based hole transport materials and their interface engineering concerning different processing methods in perovskite solar cells

In recent years, perovskite solar cells (PSCs) have become a much charming photovoltaic technology and have triggered enormous studies worldwide, owing to their high efficiency, low cost and ease of preparation. The power conversion efficiency has rapidly increased by more than 6 times to the current 25.5% in the past decade. Hole transport materials (HTMs) are an indispensable part of PSCs, which great affect the efficiency, the cost and the stability of PSCs. Inorganic Cu-based p-type semiconductors are a kind of representative inorganic HTMs in PSCs due to their unique advantages of rich variety, low cost, excellent hole mobility, adjustable energy levels, good stability, low temperature and scalable processing ability. In this review, the research progress in new materials and the control of photoelectric properties of Cu-based inorganic HTMs were first summarized systematically. And then, concerning different processing methods, advances of the interface engineering of Cu-based hole transport layers (HTLs) in PSCs were detailly discussed. Finally, the challenges and future trends of Cu-based inorganic HTMs and their interface engineering in PSCs were analyzed.

2022 Winter Olympics stamps launched

People buy commemorative stamps for the Beijing 2022 Winter Olympic Games and Paralympic Games after the launch of the stamps in Beijing on Sunday.Beijing offered a special New Year gift for philatelists and sports fans on Sunday with the launch of the first set of commemorative stamps for the 2022Beijing Winter Olympics.The inaugural set of the stamps comprises two pieces featuring the emblems of the 2022

Interface Engineering of Inverted Perovskite Solar Cells Using a Self-doped Perylene Diimide Ionene Terpolymer as a Thickness-Independent Cathode Interlayer

Inverted perovskite solar cells(PerSCs)are a highly promising candidate in the photovoltaic field due to their low-temperature fabrication process,negligible hysteresis,and easy integration with Si-based solar cells.A cathode interlayer(CIL)is necessary in the development of inverted devices to reduce the trap density and energy barrier between the electron transport layer(ETL)and the electrode.However,most CILs are highly thickness-sensitive due to low conductivity and poor film-forming.In this study,we report on a self-doping perylene imide-based ionene polymer(PNPDIN)used as CIL material to modify electrode in inverted PerSCs.PNPDIN exhibits high conductivity and a good solubility in polar solvent,which results in an improved power conversion efficiency(PCE)from 10.05%(device without a CIL)to 16.97%.When the blend of PNPDIN and Bphen was used as a mixed CIL,the PCE of PerSCs can be further increased to 21.28%owing to the excellent morphology and matched energy level.More importantly,the PCE of the device is highly tolerant to the thickness of the mixed CIL,which benefited from the high conductivity of PNPDIN.This development is expected to provide an excellent mixed CIL material for roll-to-roll processing efficient and stable inverted PerSCs.

Water-soluble copper-based simulated enzyme:Biomimetic synthesis and activities in vitro

Two copper(Ⅱ)complexes were obtained by solvothermal reaction induced by isonicotinic acid ligand through the study of natural simulated enzymes.The activity of superoxide dismutase(SOD)1 and 2 is higher than that of most Cu-SOD mimics,and they have the activity of catechol analogues.It is found that SOD activity and cat-echolase activity are directly affected by the coordination configuration of the central metal atom and the ability of the complex to accept electrons.It is also responsible for the excellent enzyme activity of these two Cu-based complexes.The results of MTT assay show that complexes 1 and 2 have no significant inhibitory effect on cell proliferation.It has good application potential in the clinical biomedical field in the future.

Advances and prospects of rare earth metal-organic frameworks in catalytic applications

In recent years,rare earth metal-organic frameworks(RE-MOFs)have attracted increasing attention because of abundant coordination behaviors,adjustable channels and stable networks.The various electron structures of rare earth ions contribute to the catalytic applications of RE-MOFs and their derivates.In this review,we systematically summarize the research progress that using RE-MOFs and their derivates as catalysts for organic reaction,photocatalytic reaction,and CO oxidation reaction.The major parts include synthetic strategies and catalytic applications of the RE-MOFs.Finally,impressive achievements of RE-MOF catalysts are emerging and a prospect is provided for the development of RE-MOF catalysts at the end of the review.

Revisiting ovarian cancer microenvironment： a friend or a foe？

Development of ovarian cancer involves the co-evolu- tion of neoplastic cells together with the adjacent microenvironment. Steps of malignant progression including primary tumor outgrowth, therapeutic resis- tance, and distant metastasis are not determined solely by genetic alterations in ovarian cancer cells, but con- siderably shaped by the fitness advantage conferred by benign components in the ovarian stroma. As the dynamic cancer topography varies drastically during disease progression, heterologous cell types within the tumor microenvironment （TME） can actively determine the pathological track of ovarian cancer. Resembling many other solid tumor types, ovarian malignancy is nurtured by a TME whose dark side may have been overlooked, rather than overestimated. Further, har- nessing breakthrough and targeting cures in human ovarian cancer requires insightful understanding of the merits and drawbacks of current treatment modalities, which mainly target transformed cells. Thus, designing novel and precise strategies that both eliminate cancer cells and manipulate the TME is increasingly recognized as a rational avenue to improve therapeutic outcome and prevent disease deterioration of ovarian cancer patients.

Genetic-algorithm-based deep neural networks for highly efficient photonic device design

While deep learning has demonstrated tremendous potential for photonic device design,it often demands a large amount of labeled data to train these deep neural network models.Preparing these data requires high-resolution numerical simulations or experimental measurements and cost significant,if not prohibitive,time and resources.In this work,we present a highly efficient inverse design method that combines deep neural networks with a genetic algorithm to optimize the geometry of photonic devices in the polar coordinate system.The method requires significantly less training data compared with previous inverse design methods.We implement this method to design several ultra-compact silicon photonics devices with challenging properties including power splitters with uncommon splitting ratios,a TE mode converter,and a broadband power splitter.These devices are free of the features beyond the capability of photolithography and generally in compliance with silicon photonics fabrication design rules.

非传统移民国家少数族群及其生活的微观研究:在俄华人移民适应问题——以伊尔库茨克华商为中心

进入全球化时代,世界范围内人口流动日趋频繁,伴随人口流动而出现的适应问题也成为民族学、人类学、社会学等多学科共同探讨的焦点议题。本文以活跃在俄罗斯伊尔库茨克市场中的华商成长历程为个案,对当今非传统移民国家少数族群的适应问题进行初步探讨。面对非移民传统国家“有限宽容”的生存环境,作为跨国经营活动的行动主体的华商依托特有的关系网络与社会结构,形成了由家庭式经营与“同乡同业”策略支持起来的群体经济,并采取“积极融入又保持距离”的策略与市场内外的活动主体展开交往。研究发现,虽然永久定居俄罗斯较为困难,但是“旅居”中的华商已成为当地社会不可或缺的一部分。华商的行动不仅挑战了旧有的“落叶归根”与“落地生根”的适应模式,还凭借中国商品将中国引入世界、推动了中国与周边国家之间经济连接与文化交流,并为审视中俄关系的发展走向提供了另一个角度。