Rechargeable zinc‐ion batteries (ZIBs) are emerging as a promising alternative for Li‐ion batteries. However, the developed cathodes suffer from sluggish Zn2+ diffusion kinetics, leading to poor rate ...capability and inadequate cycle life. Herein, an in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn2+ (de)intercalation kinetics in V2O5. In this way, a remarkably enlarged interlayer distance (13.90 Å) can be constructed alternatively between the VO layers, offering expediting channels for facile Zn2+ diffusion. Importantly, the electrostatic interactions between the Zn2+ and the host O2−, which is another key factor in hindering the Zn2+ diffusion kinetics, can be effectively blocked by the unique π‐conjugated structure of PANI. As a result, the PANI‐intercalated V2O5 exhibits a stable and highly reversible electrochemical reaction during repetitive Zn2+ insertion and extraction, as demonstrated by in situ synchrotron X‐ray diffraction and Raman studies. Further first‐principles calculations clearly reveal a remarkably lowered binding energy between Zn2+ and host O2−, which explains the favorable kinetics in PANI‐intercalated V2O5. Benefitting from the above, the overall electrochemical performance of PANI‐intercalated V2O5 electrode is remarkable improved, exhibiting excellent high rate capability of 197.1 mAh g−1 at current density of 20 A g−1 with capacity retention of 97.6% over 2000 cycles.
An in situ polyaniline (PANI) intercalation strategy is developed to facilitate the Zn2+ (de)intercalation kinetics in V2O5. PANI not only expands the diffusion channels for facilitating Zn2+ diffusion, but also maintains the structural stability as interlayer pillars. Especially, its unique π‐conjugated structure, serving as electron‐reservoir, simultaneously shields the electrostatic interactions between Zn2+ and V2O5 host.
The removal of C2H2 and C2H6 from C2H4 streams is of great significance for feedstock purification to produce polyethylene and other commodity chemicals but the simultaneous adsorption of C2H6 and ...C2H2 over C2H4 from a ternary mixture has never been realized. Herein, a robust metal–organic framework, TJT‐100, was designed and synthesized, which demonstrates remarkably selective adsorption of C2H2 and C2H6 over C2H4. Breakthrough experiments show that TJT‐100 can be used as an adsorbent for high‐performance purification of C2H4 from a ternary mixture of C2H2/C2H4/C2H6 (0.5:99:0.5) to afford a C2H4 purity greater than 99.997 %, beyond that required for ethylene polymerization. Computational studies reveal that the uncoordinated carboxylate oxygen atoms and coordinated water molecules pointing towards the pore can trap C2H2 and C2H6 through the formation of multiple C−H⋅⋅⋅O electrostatic interactions, while the corresponding C2H4–framework interaction is unfavorable.
A robust porous metal–organic framework was synthesized and utilized for the highly selective separation of C2H4 from a ternary mixture of C2 hydrocarbons. After a single operation, the C2H4 purity of the outlet was greater than 99.997 %.
Hierarchical chiral structures have broad applications in optical devices, asymmetric catalysis, and biological systems. The delicate balance of various interactions are key to the self-assembly of ...chiral structures. Herein, a ternary co-assembly consisting of cationic pillar5arenes (P5As), anionic β-glucopyranoside (βGlcD / βGlcL), and Anderson-type polyoxometalates (POMs) were constructed. Through adjusting the stoichiometry of βGlcD, the assemblies were effectively controlled to form hierarchical nano-leaf assemblies with twisted nanoribbons in a homochiral direction. The co-assemblies exhibit strong Cotton effects, and successfully induced the chirality of Anderson-type POMs. More interestingly, by changing the central metal in Anderson-type POMs (XMo6O243- (X = Cr, Al, and Ga)), even though the three clusters have the same numbers of charge and size, the hierarchical chirality of the related assemblies varied in the morphology of the assemblies and the Cotton effect in the CD spectra. Results in theoretical calculations and ITC titration indicates that the tiny difference in long-range electrostatic interaction would result in the anion recognition of POMs, modulated by βGlcD through host-guest inclusion and hydrogen bonding in the assembly process.
One of the defining properties of electrons is their mutual Coulomb repulsion. However, in solids this basic property may change; for example, in superconductors, the coupling of electrons to lattice ...vibrations makes the electrons attract one another, leading to the formation of bound pairs. Fifty years ago it was proposed that electrons can be made attractive even when all of the degrees of freedom in the solid are electronic, by exploiting their repulsion from other electrons. This attraction mechanism, termed 'excitonic', promised to achieve stronger and more exotic superconductivity. Yet, despite an extensive search, experimental evidence for excitonic attraction has yet to be found. Here we demonstrate this attraction by constructing, from the bottom up, the fundamental building block of the excitonic mechanism. Our experiments are based on quantum devices made from pristine carbon nanotubes, combined with cryogenic precision manipulation. Using this platform, we demonstrate that two electrons can be made to attract each other using an independent electronic system as the 'glue' that mediates attraction. Owing to its tunability, our system offers insights into the underlying physics, such as the dependence of the emergent attraction on the underlying repulsion, and the origin of the pairing energy. We also demonstrate transport signatures of excitonic pairing. This experimental demonstration of excitonic pairing paves the way for the design of exotic states of matter.
The aim of this work was to characterize the complexes lysozyme (Lyso)/xanthan gum (XG) and ovalbumin (Ova)/xanthan gum in terms of their physicochemical properties and to study the influence of salt ...and protein/polysaccharide ratio on rheological properties. As the protein/polysaccharide ratio was increased from 1:1 to 10:1, critical structure events shifted to higher pHs, resulting in the formation of insoluble complexes even at pH 12.0. Lyso/XG complex formed a stronger gel-like complex with smaller loss tangents compared with the Ova/XG complex; however, those gels showed a slight tendency to breakdown under higher frequency variation when compared with Ova/XG complex. The correlation between rheological data, the effect of ionic strength and FTIR analysis suggests that although an electrostatic interaction is the main mechanism of interaction between biopolymers, non-electrostatic interactions also plays a role in the strength of the interaction. Egg white protein/XG complexes represent a great technological to formulate functional hydrogels.
Display omitted
•Electrostatic interaction is the main mechanism of interaction between biopolymers.•The addition of NaCl decreases the complexation Lyso/XG and Ova/XG.•The rheological data of the complexes showed a gel-like network structure.•Egg white protein/XG complexes represent a great technological opportunity.
The non-receptor protein tyrosine phosphatase (PTP) SHP2, encoded by PTPN11, plays an essential role in RAS-mitogen-activated protein kinase (MAPK) signaling during normal development. It has been ...perplexing as to why both enzymatically activating and inactivating mutations in PTPN11 result in human developmental disorders with overlapping clinical manifestations. Here, we uncover a common liquid-liquid phase separation (LLPS) behavior shared by these disease-associated SHP2 mutants. SHP2 LLPS is mediated by the conserved well-folded PTP domain through multivalent electrostatic interactions and regulated by an intrinsic autoinhibitory mechanism through conformational changes. SHP2 allosteric inhibitors can attenuate LLPS of SHP2 mutants, which boosts SHP2 PTP activity. Moreover, disease-associated SHP2 mutants can recruit and activate wild-type (WT) SHP2 in LLPS to promote MAPK activation. These results not only suggest that LLPS serves as a gain-of-function mechanism involved in the pathogenesis of SHP2-associated human diseases but also provide evidence that PTP may be regulated by LLPS that can be therapeutically targeted.
Display omitted
•Disease-associated mutations endow SHP2 liquid-liquid phase separation capability•SHP2 LLPS is driven by electrostatic interactions mediated by PTP domain•SHP2 allosteric inhibitors block SHP2 LLPS by locking SHP2 in closed conformation•Mutant SHP2 can recruit and activate WT SHP2 in LLPS to promote MAPK activation
Disease-associated mutants of a critical phosphatase in the RAS-MAPK pathway undergo phase separation through a dominant gain-of-function mechanism, explaining how both enzymatically activating and inactivating mutations dysregulate the pathway and can be therapeutically targeted.
Intracellular ribonucleoprotein (RNP) granules are membrane‐less droplet organelles that are thought to regulate posttranscriptional gene expression. While liquid–liquid phase separation may drive ...RNP granule assembly, the mechanisms underlying their supramolecular dynamics and internal organization remain poorly understood. Herein, we demonstrate that RNA, a primary component of RNP granules, can modulate the phase behavior of RNPs by controlling both droplet assembly and dissolution in vitro. Monotonically increasing the RNA concentration initially leads to droplet assembly by complex coacervation and subsequently triggers an RNP charge inversion, which promotes disassembly. This RNA‐mediated reentrant phase transition can drive the formation of dynamic droplet substructures (vacuoles) with tunable lifetimes. We propose that active cellular processes that can create an influx of RNA into RNP granules, such as transcription, can spatiotemporally control the organization and dynamics of such liquid‐like organelles.
Vacuolated ribonucleoprotein droplets: RNA controls the reentrant phase transition of ribonucleoproteins (RNPs) to assemble and dissolve RNP droplets. During dissolution, controlled RNA flux into the RNP droplets generates dynamic vacuolated substructures with tunable lifetimes.
PDF
