News on China's scientific and technological development.

tokenanalyst said:

Shanghai Silicate Institute has made new progress in the research of 3D printing silicon carbide ceramics​

Silicon carbide (SiC) ceramics have become an urgent problem to be overcome in 3D printing ceramics due to their easy oxidation, difficult melting, and high light absorption. At present, most 3D printing SiC ceramic methods have low solid content, high silicon content, and mechanical properties. Lower, generally adopt chemical vapor deposition CVI (Chemical Vapor Infiltration) or precursor impregnation pyrolysis PIP (Precursor Infiltration Pyrolysis) and other post-processing processes to increase the solid content of the material to achieve the improvement of the comprehensive performance of the ceramic material, which is bound to reduce the 3D printing SiC ceramic process. the superiority.

Schematic diagram of 3D printing of SiC ceramics

Recently, associate researcher Chen Jian of the research team of Huang Zhengren from Shanghai Institute of Ceramics, Chinese Academy of Sciences proposed for the first time a new method of high temperature fused deposition combined with reaction sintering to prepare SiC ceramics. The method adopts high-temperature in-situ interface modification powder and slow-release of low-temperature stress to prepare a high-plasticity printing body, and obtains a high-plasticity printing body with low melting point and high boiling point, and the solid content of the material exceeds 60vol%; After printing, the equivalent carbon density of the printed ceramic sample can be precisely adjusted to 0.80 g·cm-3 after degreasing. At the same time, the topology optimization design of the ceramic printing path can form tree-shaped multi-level pores in the sample; the final ceramic sample does not require CVI or After PIP treatment, direct reaction silicon infiltration and sintering can achieve high-efficiency infiltration of low residual silicon/carbon and material densification. The amount is 346.35±22.80 GPa, and the mechanical properties of the ceramics are close to those of the reaction-sintered SiC ceramics prepared by the traditional method. Relevant research results were published in Additive Manufacturing (doi.org/10.1016/j.addma.2022.102994), and 2 Chinese invention patents were applied for. At the same time, the plastomer printing method avoids the potential harm of powder printing under microgravity conditions, which is a future space 3D printing offers the possibility.

SiC ceramics of different shapes and sizes

The co-first authors of the paper are master student Li Fanfan and doctoral student Ma Ningning of Shanghai Institute of Ceramics, and the corresponding authors are associate researcher Chen Jian and researcher Huang Zhengren. Relevant research has been funded and supported by the National Key R&D Program, the National Natural Science Foundation of China, and the Shanghai Natural Science Foundation.

Machined ~200mm 3D printed SiC ceramic

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latenlazy said:

Can you share the original link? This post reads like it was machine translated.

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The IT Security Law passed by the Merkel government in April 2021 did not explicitly ban suppliers like China’s Huawei, but instead set up a complex two-step assessment process that left it to the next government to decide which suppliers of critical components are considered trustworthy and which are not. People familiar with the Scholz government’s thinking told me that it was highly unlikely that Chinese suppliers would be allowed in. “We have a new political constellation,” one official said. “Under Merkel there was no consensus. Now there is.” Still, this is one to watch.

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escobar said:

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新华社哈尔滨7月6日电（记者闫睿）记者5日从中国农业科学院哈尔滨兽医研究所获悉，该所研究员、中国科学院陈化兰院士团队在H5N1亚型高致病性禽流感病毒研究方面取得重要进展，系统阐明了目前在全球肆虐的H5N1禽流感病毒的起源、进化和时空传播特征，并对我国监测到的H5N1病毒进行了系统的生物学研究。

研究发现，目前流行的H5N1病毒于2020年10月在欧洲国家出现，是由H5N8禽流感病毒与H1N1及H3N8等亚型禽流感病毒重配而来。2020年10月至2021年8月，该新型H5N1病毒在西欧、北欧和东欧多国的家禽和野鸟中流行，并传播至多个非洲国家。2021年9月起在欧洲引起禽流感大暴发，并传播到亚洲和北美洲多个国家。

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团队介绍，由于疫苗免疫的保护作用，这些全球流行的H5禽流感病毒，虽由野鸟传入我国，但对我国家禽未造成实质危害。

陈化兰院士团队通过抗原性分析发现，我国目前使用的H5-Re14疫苗毒株与其抗原性匹配良好，证明H5和H7三价禽流感灭活疫苗可有效阻断此类H5N1病毒入侵免疫家禽。鉴于此类H5N1病毒在全球野鸟中广泛分布，团队成员呼吁高风险国家对家禽进行H5亚型禽流感疫苗免疫，有效阻断病毒由野鸟传播进入家禽，从而有效降低其对人类健康带来的威胁。

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Modulating terahertz (THz) waves actively and smartly through an external field is highly desired in the development of THz spectroscopic devices. Here, we demonstrate an active and smart electro-optic THz modulator based on a strongly correlated electron oxide vanadium dioxide (VO2). With milliampere current excitation on the VO2 thin film, the transmission, reflection, absorption, and phase of THz waves can be modulated efficiently. In particular, the antireflection condition can be actively achieved and the modulation depth reaches 99.9%, accompanied by a 180° phase switching. Repeated and current scanning experiments confirm the high stability and multibit modulation of this electro-optic modulation. Most strikingly, by utilizing a feedback loop of “THz-electro-THz” geometry, a smart electro-optic THz control is realized. For instance, the antireflection condition can be stabilized precisely no matter what the initial condition is and how the external environment changes. The proposed electro-optic THz modulation method, taking advantage of strongly correlated electron material, opens up avenues for the realization of THz smart devices.

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近日，中国科学院合肥物质科学研究院强磁场中心研究员盛志高团队依托稳态强磁场实验装置研发了一种主动、智能化的太赫兹电光调制器。相关研究成果发表在ACS Applied Materials & Interfaces上。

虽然太赫兹技术具有优越的波谱特性和广泛的应用前景，但其工程应用还严重受制于太赫兹材料与太赫兹元器件的开发。其中，围绕智能化场景应用，采用外场对太赫兹波进行主动、智能化的控制是这一领域的重要研究方向。
瞄准太赫兹核心元器件这一前沿研究方向，研究团队在发明了基于二维材料石墨烯的太赫兹应力调制器【Adv. Optical Mater. 6, 1700877(2018)】、基于强关联氧化物的太赫兹宽带光控调制器【ACS Appl. Mater. Inter. 12, 48811(2020)】和基于声子的新型单频磁控太赫兹源【Advanced Science 9, 2103229(2021)】之后，选择关联电子氧化物二氧化钒薄膜作为功能层，采用多层结构设计和电控方法，实现了太赫兹透射、反射和吸收多功能主动调制（图a）。研究结果表明，除了透射率和吸收率，反射率和反射相位也可被电场主动调控，其中反射率调制深度可以达到99.9%、反射相位可达~180o调制（图b）。更为有趣的是，为了实现智能化的太赫兹电控，研究人员设计了一种具有新型“太赫兹-电-太赫兹”的反馈回路的器件（图c）。不管起始条件和外界环境如何变化，该智能器件可以在30秒左右自动达到太赫兹的设定（预期）调制值。
这一基于关联电子材料的主动、智能化太赫兹电光调制器的研发为太赫兹智能化控制的实现提供了新的思路。该工作获得国家重点研发计划、国家自然科学基金、强磁场安徽省实验室方向基金的支持。

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a）基于VO2的电光调制器示意图（b）透射率、反射率、吸收率和反射相位随外加电流变化（c）智能化控制原理图

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escobar said:

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xypher said:

So it means that there would be no hard feelings if VW is booted out of the Chinese market? New political constellation 'n shit. But who am I kidding - they would be screaming and crying everywhere if that happens.

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