The real capacity of graphene and the lithium-storage process in graphite are two currently perplexing problems in the field of lithium ion batteries. Here we demonstrate a three-dimensional bilayer ...graphene foam with few defects and a predominant Bernal stacking configuration, and systematically investigate its lithium-storage capacity, process, kinetics, and resistances. We clarify that lithium atoms can be stored only in the graphene interlayer and propose the first ever planar lithium-intercalation model for graphenic carbons. Corroborated by theoretical calculations, various physiochemical characterizations of the staged lithium bilayer graphene products further reveal the regular lithium-intercalation phenomena and thus fully illustrate this elementary lithium storage pattern of two-dimension. These findings not only make the commercial graphite the first electrode with clear lithium-storage process, but also guide the development of graphene materials in lithium ion batteries.
Graphene-covering is a promising approach for achieving an acid-stable, non-noble-metal-catalysed hydrogen evolution reaction (HER). Optimization of the number of graphene-covering layers and the ...density of defects generated by chemical doping is crucial for achieving a balance between corrosion resistance and catalytic activity. Here, we investigate the influence of charge transfer and proton penetration through the graphene layers on the HER mechanisms of the non-noble metals Ni and Cu in an acidic electrolyte. We find that increasing the number of graphene-covering layers significantly alters the HER performances of Ni and Cu. The proton penetration explored through electrochemical experiments and simulations reveals that the HER activity of the graphene-covered catalysts is governed by the degree of proton penetration, as determined by the number of graphene-covering layers.
To realize a sustainable hydrogen economy, corrosion‐resistant non‐noble‐metal catalysts are needed to replace noble‐metal‐based catalysts. The combination of passivation elements and catalytically ...active elements is crucial for simultaneously achieving high corrosion resistance and high catalytic activity. Herein, the self‐selection/reconstruction characteristics of multi‐element (nonary) alloys that can automatically redistribute suitable elements and rearrange surface structures under the target reaction conditions during the oxygen evolution reaction are investigated. The following synergetic effect (i.e., cocktail effect), among the elements Ti, Zr, Nb, and Mo, significantly contributes to passivation, whereas Cr, Co, Ni, Mn, and Fe enhance the catalytic activity. According to the practical water electrolysis experiments, the self‐selected/reconstructed multi‐element alloy demonstrates high performance under a similar condition with proton exchange membrane (PEM)‐type water electrolysis without obvious degradation during stability tests. This verifies the resistance of the alloy to corrosion when used as an electrode under a practical PEM electrolysis condition.
Corrosion‐resistant non‐noble‐metal catalysts demonstrate the possibility of replacing noble metals such as IrO2 as anode catalysts in acidic media. The place replacement of Ni and Co as catalytically active elements in passivation elements such as Ti, Zr, Nb, and Mo plays an important role in enhancing oxygen evolution reaction activity.
Catalyzing oxygen reduction reaction (ORR) and accelerating oxygen diffusion are two key challenges for the requirements of the cathode catalysts in the metal‐air batteries. A promising strategy for ...improving both ORR performance and mass diffusion simultaneously is to build carbon‐based catalysts with ORR‐active chemical dopants and 3D interconnected porosity. Herein, a 3D nanoporous N‐doped carbon with bicontinuous porosity and interconnected open‐pore channels is reported, which is prepared by a polyaniline‐assisted template method. The polyaniline can efficiently inhibit the surface diffusion‐caused template coarsening, achieving a small pore size of 35 nm. The small porous morphology gives rise to a high N‐dopant concentration up to 7.20 at.%, which in turn exhibits a commercial Pt/C‐comparable ORR performance together with satisfied durability in alkaline media. Using these nanoporous carbon catalysts as air electrodes, an all‐solid‐state flexible Al‐air battery is assembled with the measured maximum power density reaching 130.5 mW cm−2, as compared to 106.2 mW cm−2 when the commercial Pt/C standard is used. This study provides an efficient method to synthesize 3D N‐doped carbon with bicontinuous nano‐sized pore channels for wide‐ranging applications in portable and flexible devices.
A polyaniline‐assisted template method is developed to synthesize the nanoporous bicontinuous N‐doped carbon particles, achieving a small pore size of 35 nm. The polyaniline plays a key role in the suppression of surface diffusion and pore enlargement of the Mn2O3 template at the high pyrolysis temperature. The product exhibits excellent electrocatalytic activity in all‐solid‐state Al‐air batteries.
The first pathology observed in Parkinson's disease (PD) is 'dying back' of striatal dopaminergic (DA) terminals. Connexin (Cx)30, an astrocytic gap junction protein, is upregulated in the striatum ...in PD, but its roles in neurodegeneration remain elusive. We investigated Cx30 function in an acute PD model by administering 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to wild-type (WT) and Cx30 knockout (KO) mice.
On days 1 and 7 after MPTP administration, we evaluated changes in astrocytic Cx30, Cx43, glial fibrillary acidic protein, and ionised calcium-binding adapter molecule 1 expression by immunostaining and biochemical analysis. Loss of DA neurons was evaluated by tyrosine hydroxylase immunostaining. Gene expression was analysed using A1, A2, pan-reactive astrocyte microarray gene sets, and M1, M2, and M1/M2 mixed microglial microarray gene sets. Real-time PCR and in situ hybridisation were performed to evaluate glial cell-derived neurotrophic factor (Gdnf) and S100a10 expression. Striatal GDNF protein levels were determined by enzyme-linked immunosorbent assay.
MPTP treatment induced upregulation of Cx30 and Cx43 levels in the striatum of WT and KO mice. DA neuron loss was accelerated in Cx30 KO compared with WT mice after MPTP administration, despite no change in the striatal concentration of methyl-4-phenylpyridinium
. Astrogliosis in the striatum of Cx30 KO mice was attenuated by MPTP, whereas microglial activation was unaffected. Microarrays of the striatum showed reduced expression of pan-reactive and A2 astrocyte genes after MPTP treatment in Cx30 KO compared with WT mice, while M1, M2, and M1/M2 mixed microglial gene expression did not change. MPTP reduced the number of striatal astrocytes co-expressing Gdnf mRNA and S100β protein or S100a10 mRNA and S100β protein and also reduced the level of GDNF in the striatum of Cx30 KO compared with WT mice.
These findings indicate that Cx30 plays critical roles in astrocyte neuroprotection in an MPTP PD model.
We studied the shear-thickening behavior of systems containing rigid spherical bodies immersed in smaller particles using non-equilibrium molecular dynamics simulations. We generated shear-thickening ...states through particle mass modulation of the systems. From the microstructures, i.e., two-dimensional pair distribution functions, we found anisotropic structures resulting from shear thickening, that are explained by the difference between the velocities of rigid bodies and fluid particles. The increasing viscosity in our system originated from collisions between fluid particles and rigid bodies. The lubrication forces defined in macroscale physics are then briefly discussed.
We performed molecular dynamics simulations of carbon nanotube (CNT) to elucidate the growth process in the floating catalyst chemical vapor deposition method (FCCVD). FCCVD has two features: a ...nanometer-sized cementite (Fe
C) particle whose melting point is depressed because of the larger surface-to-volume ratio and tensile strain between the growing CNT and the catalyst. The simulations, including these effects, demonstrated that the number of 6-membered rings of the (6,4) chiral CNT constantly increased at a speed of
at
, whereas those of the armchair and zigzag CNTs were stopped in the simulations and only reached half of the numbers for chiral CNT. Both the temperature and CNT chirality significantly affected CNT growth under tensile strain.
Potential risks of supply shortages for critical metals including rare-earth elements and yttrium (REY) have spurred great interest in commercial mining of deep-sea mineral resources. Deep-sea mud ...containing over 5,000 ppm total REY content was discovered in the western North Pacific Ocean near Minamitorishima Island, Japan, in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features. Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km
× 0-10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively. Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future.
Parkinson's disease (PD) symptoms do not become apparent until most dopaminergic neurons in the substantia nigra pars compacta (SNc) degenerate, suggesting that compensatory mechanisms play a role. ...Here, we investigated the compensatory involvement of activated microglia in the SN pars reticulata (SNr) and the globus pallidus (GP) in a 6‐hydroxydopamine‐induced rat hemiparkinsonism model. Activated microglia accumulated more markedly in the SNr than in the SNc in the model. The cells had enlarged somata and expressed phagocytic markers CD68 and NG2 proteoglycan in a limited region of the SNr, where synapsin I‐ and postsynaptic density 95‐immunoreactivities were reduced. The activated microglia engulfed pre‐ and post‐synaptic elements, including NMDA receptors into their phagosomes. Cells in the SNr and GP engulfed red fluorescent DiI that was injected into the subthalamic nucleus (STN) as an anterograde tracer. Rat primary microglia increased their phagocytic activities in response to glutamate, with increased expression of mRNA encoding phagocytosis‐related factors. The synthetic glucocorticoid dexamethasone overcame the stimulating effect of glutamate. Subcutaneous single administration of dexamethasone to the PD model rats suppressed microglial activation in the SNr, resulting in aggravated motor dysfunctions, while expression of mRNA encoding glutamatergic, but not GABAergic, synaptic elements increased. These findings suggest that microglia in the SNr and GP become activated and selectively eliminate glutamatergic synapses from the STN in response to increased glutamatergic activity. Thus, microglia may be involved in a negative feedback loop in the indirect pathway of the basal ganglia to compensate for the loss of dopaminergic neurons in PD brains.
Main Points
Microglia eliminate glutamatergic synapses from the subthalamic nuclei in basal ganglia outputs in a rat parkinsonism model.
By eliminating synapses, microglia give negative feedback compensating for dopaminergic neuron loss.
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•Rheological properties of 1-ethyl-3-methylimidazolium / tetrafluoroborate.•NEMD showed imidazolium-based ionic liquids (IL) exhibiting shear thinning.•The Eyring model well described ...shear thinning obtained in NEMD simulations.•We investigated contributions to energy barriers underlying shear thinning.•Electrostatic interactions play an important role in the shear-thinning of IL.
We investigated rheological properties of 1-ethyl-3-methylimidazolium tetrafluoroborate as neat ionic liquid. We computed the shear viscosity at various shear rates using non-equilibrium molecular dynamics and observed a plateau regime prior to a decrease related to shear thinning. We employed a 1-dimensional diffusive model based on the Eyring one to investigate underlying molecular mechanisms. Shear thinning results from an apparent decrease of energy barriers encountered by ions when migrating from one metastable state to another one in a shear flow. Electrostatic interactions contribute to ∼55% of those energy barriers. This method and findings set the basis for considering more complex ionic liquids.
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