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相关概念视频

Network Covalent Solids02:18

Network Covalent Solids

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Network covalent solids contain a three-dimensional network of covalently bonded atoms as found in the crystal structures of nonmetals like diamond, graphite, silicon, and some covalent compounds, such as silicon dioxide (sand) and silicon carbide (carborundum, the abrasive on sandpaper). Many minerals have networks of covalent bonds.
To break or to melt a covalent network solid, covalent bonds must be broken. Because covalent bonds are relatively strong, covalent network solids are typically...
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Porosity and Absorption of Aggregate01:20

Porosity and Absorption of Aggregate

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Aggregates contain pores of varying sizes; while some are completely enclosed within the particles, others open onto the surface, allowing water to penetrate. The porosity of aggregates is a major factor contributing to the overall porosity of concrete, given that aggregates constitute about three-quarters of concrete's volume.
When all pores in an aggregate are filled with water, the aggregate is considered saturated and surface-dry. If left in dry air, water will evaporate until the...
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Structure of Porins01:21

Structure of Porins

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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a  motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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Crystal Field Theory - Octahedral Complexes02:58

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Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
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Pore Size Distribution01:23

Pore Size Distribution

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In concrete, the pore size distribution significantly influences the material's properties. Capillary pores, markedly larger than gel pores, form a vast network within partially hydrated cement paste, reducing the concrete's strength and increasing its permeability. This heightened permeability leads to a greater risk of damage from environmental factors like freeze-thaw cycles and chemical attacks, with the extent of vulnerability also being tied to the water-to-cement ratio.
Adequate...
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Aromatic Hydrocarbon Anions: Structural Overview01:18

Aromatic Hydrocarbon Anions: Structural Overview

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Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
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具有记录孔径的共价有机框架

Zhenjie Mu1, Yuhao Zhu1, Bixiao Li1

  • 1Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials, Key Laboratory of Cluster Science, Ministry of Education, Advanced Technology Research Institute (Jinan), Frontiers Science Center for High Energy Material, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing 100081, P. R. China.

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|March 8, 2022
PubMed
概括

研究人员开发了新的共价有机框架 (COF),具有高达10.0纳米的记录大,均的中介孔. 这些稳定,结晶的材料可以分离像素这样的大生物分子并保护酶.

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科学领域:

  • 材料科学
  • 聚合物化学
  • 纳米技术

背景情况:

  • 具有可调节孔径的多孔材料对于分子分离和保护至关重要.
  • 现有的金属有机框架 (MOF) 和共价有机框架 (COF) 在孔径大小上有局限性,阻碍了大分子的进入.
  • 在晶体多孔聚合物中实现均的大质孔仍然是一个重大挑战.

研究的目的:

  • 构建新的共价有机框架 (COF) 破纪录,预先设计的中孔孔.
  • 克服相互透和结构脆弱的局限性,以创造具有大孔的COF.
  • 在涉及大型生物分子的实际应用中证明这些新型COF的实用性.

主要方法:

  • 设计和合成具有增强形态刚性,平面性和控制局部极性的新型构件.
  • 由此产生的共价有机框架 (COFs) 的结晶性,孔隙性,稳定性和孔隙大小分布的表征.
  • 合成的COF用于生物分子分离和酶保护.

主要成果:

  • 一系列共价有机框架 (COF) 已成功合成,孔径值在7.7~10.0nm之间,超过了之前的记录.
  • 获得的COF具有高结晶性,永久性多孔性,结构稳定性,并显示了叠加性.
  • 从原始混合物中成功分离素 (大约7纳米),并保护酸酶免受热诱导的变性.

结论:

  • 开发的策略可以构建具有前所未有的大小和均度的共价有机框架 (COF).
  • 这些新型COF为先进的分离技术和生物分子稳定提供了重大潜力.
  • 这些发现为设计下一代多孔材料为复杂的分子相互作用铺平了道路.