Hard Carbon Derived From Different Precursors for Sodium Storage.

Due to the almost unlimited resource and acceptable performance, Sodium-ion batteries (SIBs) have been regarded as a promising alternative for lithium-ion batteries (LIBs) for grid-scale energy storage. As the key material of SIBs, hard carbon (HC) plays a decisive role in determining the batteries' performance. Nevertheless, the micro-structure of HCs is quite complex and the random organization of turbostratically stacked graphene layers, closed pores, and defects make the structure-performance relationship insufficiently revealed. On the other hand, the impending large-scale deployment of SIBs leads to producing HCs with low-cost and abundant precursors actively pursued. In this work, the recent progress of preparing HCs from different precursors including biomass, polymers, and fossil fuels is summarized with close attention to the influences of precursors on the structural evolution of HCs. After a brief introduction of the structural features of HCs, the recent understanding of the structure-performance relationship of HCs for sodium storage is summarized. Then, the main focus is concentrated on the progress of producing HCs from distinct precursors. After that, the pros and cons of HCs derived from different precursors are comprehensively compared to conclude the selection rules of precursors. Finally, the further directions of HCs are deeply discussed to end this review.

Sex differences in subjective cognitive impairment and clinical correlates in Chinese patients with subthreshold depression.

OBJECTIVE: Subthreshold depression (SD) is a global mental health problem given its high prevalence, comorbidity, functional impairment, and its association with increased service utilization. However, currently little is known about sex differences of SD in cognitive impairment with clinical correlates. This study aims to explore sex differences in subjective cognitive impairment and clinically associated risk factors in Chinese patients with subthreshold depression (SD). METHODS: A total of 126 patients with SD, 40 males and 86 females, aged 18-45 years, were included in this cross-sectional observational study. Their general information, psychological assessments, and psychiatric symptom assessments were collected online. The Patient Health Questionnaire depression-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Perceived Deficits Questionnaire-Depression (PDQ-D), and Toronto Alexithymia Scale (TAS-20) with 3 subdomains were used. The obtained scores were analyzed with partial correlation and multiple linear regression analysis models. RESULTS: Our results showed that females had significantly higher PDQ-D-20 total score than males. However, the differences in TAS-20 and subdomain score according to sex were not significant. Notably, TAS-20 and DDF (difficulty describing feelings) subdomain contributed to cognitive impairment in males, whereas both PHQ-9 total score and TAS-20 or DDF subdomain contributed to cognitive impairment in females. CONCLUSION: These findings revealed significant sex differences in cognitive impairment and clinical correlates in SD, which should be further followed-up in the future.

Formation Mechanism of Chemically Precompressed Hydrogen Clathrates in Metal Superhydrides.

Recently, the experimental discovery of high-Tc superconductivity in compressed hydrides H3S and LaH10 at megabar pressures has triggered searches for various superconducting superhydrides. It was experimentally observed that thorium superhydrides, ThH10 and ThH9, are stabilized at much lower pressures than LaH10. Based on first-principles density functional theory calculations, we reveal that the isolated Th frameworks of ThH10 and ThH9 have relatively more excess electrons in interstitial regions than the La framework of LaH10. Such interstitial excess electrons easily participate in the formation of the anionic H cage surrounding the metal atom. The resulting Coulomb attraction between cationic Th atoms and anionic H cages is estimated to be stronger than the corresponding one of LaH10, thereby giving rise to larger chemical precompressions in ThH10 and ThH9. Such a formation mechanism of H clathrates can also be applied to other superhydrides such as CeH9, PrH9, and NdH9. Our findings demonstrate that interstitial excess electrons in the isolated metal frameworks of high-pressure superhydrides play an important role in generating the chemical precompression of H clathrates.

Ferromagnetic Weyl Fermions in Two-Dimensional Layered Electride Gd_{2}C.

Recently, two-dimensional layered electrides have emerged as a new class of materials which possess anionic electrons in the interstitial spaces between cationic layers. Here, based on first-principles calculations, we discover a time-reversal-symmetry-breaking Weyl semimetal phase in a unique two-dimensional layered ferromagnetic (FM) electride Gd_{2}C. It is revealed that the crystal field mixes the interstitial electron states and Gd-5d orbitals near the Fermi energy to form band inversions. Meanwhile, the FM order induces two spinful Weyl nodal lines (WNLs), which are converted into multiple pairs of Weyl nodes through spin-orbit coupling. Further, we not only identify Fermi-arc surface states connecting the Weyl nodes but also predict a large intrinsic anomalous Hall conductivity due to the Berry curvature produced by the gapped WNLs. Our findings demonstrate the existence of Weyl fermions in the room-temperature FM electride Gd_{2}C, therefore offering a new platform to investigate the intriguing interplay between electride materials and magnetic Weyl physics.

Origin of enhanced chemical precompression in cerium hydride [Formula: see text].

The rare-earth metal hydrides with clathrate structures have been highly attractive because of their promising high-[Formula: see text] superconductivity at high pressure. Recently, cerium hydride [Formula: see text] composed of Ce-encapsulated clathrate H cages was synthesized at much lower pressures of 80-100 GPa, compared to other experimentally synthesized rare-earth hydrides such as [Formula: see text] and [Formula: see text]. Based on density-functional theory calculations, we find that the Ce 5p semicore and 4f/5d valence states strongly hybridize with the H 1s state, while a transfer of electrons occurs from Ce to H atoms. Further, we reveal that the delocalized nature of Ce 4f electrons plays an important role in the chemical precompression of clathrate H cages. Our findings not only suggest that the bonding nature between the Ce atoms and H cages is characterized as a mixture of ionic and covalent, but also have important implications for understanding the origin of enhanced chemical precompression that results in the lower pressures required for the synthesis of [Formula: see text].

Band gap scaling laws in group IV nanotubes.

By using the first-principles calculations, the band gap properties of nanotubes formed by group IV elements have been investigated systemically. Our results reveal that for armchair nanotubes, the energy gaps at K points in the Brillouin zone decrease as 1/r scaling law with the radii (r) increasing, while they are scaled by -1/r 2 + C at Γ points, here, C is a constant. Further studies show that such scaling law of K points is independent of both the chiral vector and the type of elements. Therefore, the band gaps of nanotubes for a given radius can be determined by these scaling laws easily. Interestingly, we also predict the existence of indirect band gap for both germanium and tin nanotubes. Our new findings provide an efficient way to determine the band gaps of group IV element nanotubes by knowing the radii, as well as to facilitate the design of functional nanodevices.

RNA interference targeting the platelet-derived growth factor receptor beta subunit ameliorates experimental hepatic fibrosis in rats.

BACKGROUND/AIMS: Platelet-derived growth factor (PDGF) is the strongest stimulator of the proliferation of hepatic stellate cells (HSCs). PDGF receptor beta subunit (PDGFR-beta) is acquired on HSCs proliferation induced by PDGF. In this study, we aim to investigate the effect of PDGFR-beta small interference RNA (siRNA) on experimental hepatic fibrosis. METHODS: We constructed a PDGFR-beta siRNA expression plasmid and investigated its effect on the activation of HSCs. Bromodeoxyuridine incorporation was performed to investigate the effect of PDGFR-beta siRNA on HSCs proliferation. A hydrodynamics-based transfection method was used to deliver PDGFR-beta siRNA to rats with hepatic fibrosis. The distribution of transgenes in the liver was observed by immunofluorescence. The antifibrogenic effect of PDGFR-beta siRNA was investigated pathologically. RESULTS: Platelet-derived growth factor receptor-beta subunit siRNA could significantly downregulate PDGFR-beta expression, suppress HSCs activation, block the mitogen-activated protein kinase signalling pathway and inhibit HSCs proliferation in vitro. PDGFR-beta siRNA expression plasmid could be delivered into activated HSCs by the hydrodynamics-based transfection method, and remarkably improve the liver function of the rat model induced by dimethylnitrosamine and bile duct ligation. Furthermore, the progression of fibrosis in the liver was significantly suppressed by PDGFR-beta siRNA in both animal models. CONCLUSIONS: Platelet-derived growth factor receptor-beta subunit siRNA may be presented as an effective antifibrogenic gene therapeutic method for hepatic fibrosis.