Superconductivity in Potassium-Doped Few-Layer Graphene

Here we report the successful synthesis of superconducting potassium-doped few-layer graphene (K-doped FLG) with a transition temperature of 4.5 K, which is 1 order of magnitude higher than that observed in the bulk potassium graphite intercalation compound (GIC) KC₈ (<i>T</i>_c = 0.39 K). The realization of superconductivity in K-doped FLG shows the potential for the development of new superconducting electronic devices using two-dimensional (2D) graphene as a basis material

Structural Channels and Atomic-Cluster Insertion in Cs_<i>x</i>Bi₄Te₆ (1 ≤ <i>x</i> ≤ 1.25) As Observed by Aberration-Corrected Scanning Transmission Electron Microscopy

Microstructural analyses based on aberration-corrected scanning transmission electron microscopy (STEM) observations demonstrate that low-dimensional Cs_<i>x</i>Bi₄Te₆ materials, known to be a novel thermoelectric and superconducting system, contain notable structural channels that go directly along the <i>b</i> axis, which can be partially filled by atom clusters depending on the thermal treatment process. We successfully prepared two series of Cs_<i>x</i>Bi₄Te₆ single-crystalline samples using two different sintering processes. The Cs_<i>x</i>Bi₄Te₆ samples prepared using an air-quenching method show superconductivity at approximately 4 K, while the Cs_<i>x</i>Bi₄Te₆ with the same nominal compositions prepared by slowly cooling are nonsuperconductors. Moreover, atomic structural investigations of typical samples reveal that the structural channels are often empty in superconducting materials; thus, we can represent the superconducting phase as Cs_1–<i>y</i>Bi₄Te₆ with considering the point defects in the Cs layers. In addition, the channels in the nonsuperconducting crystals are commonly partially occupied by triplet Bi clusters. Moreover, the average structures for these two phases are also different in their monoclinic angles (β), which are estimated to be 102.3° for superconductors and 100.5° for nonsuperconductors

De Novo Molecular Design of a Novel Octapeptide That Inhibits In Vivo Melanogenesis and Has Great Transdermal Ability

Cutaneous hyperpigmentation from excess melanogenesis causes serious pigmentary disorders and even melasma. Short peptides (SPs) are garnering attention lately owing to their therapeutic potential in dermatological diseases and low systemic side effects. Here, we show an octapeptide, ansin2, designed de novo from antioxidant SPs we previously reported, significantly inhibiting melanogenesis in B16 cells by decreasing tyrosinase production via regulating the MITF pathway. Ansin2 could also inhibit tyrosinase function by covering its catalytic pocket, which was simulated in docking and LIGPLOT studies. Topical application of ansin2 exhibited evident protection in UVB-induced pigmentation in guinea pig models both in terms of prophylaxis and treatment. Interestingly, unlike other hydrophilic and peptidic drugs that need delivery systems, ansin2 can be efficiently delivered topically to the epidermis and dermis per se without an affiliated moiety. Given that ansin2 lacks unwanted toxicities and immunogenicity, it holds great potential in treating hyperpigmentation in the cosmetics and pharmaceutical industries

De Novo Molecular Design of a Novel Octapeptide That Inhibits In Vivo Melanogenesis and Has Great Transdermal Ability

Cutaneous hyperpigmentation from excess melanogenesis causes serious pigmentary disorders and even melasma. Short peptides (SPs) are garnering attention lately owing to their therapeutic potential in dermatological diseases and low systemic side effects. Here, we show an octapeptide, ansin2, designed de novo from antioxidant SPs we previously reported, significantly inhibiting melanogenesis in B16 cells by decreasing tyrosinase production via regulating the MITF pathway. Ansin2 could also inhibit tyrosinase function by covering its catalytic pocket, which was simulated in docking and LIGPLOT studies. Topical application of ansin2 exhibited evident protection in UVB-induced pigmentation in guinea pig models both in terms of prophylaxis and treatment. Interestingly, unlike other hydrophilic and peptidic drugs that need delivery systems, ansin2 can be efficiently delivered topically to the epidermis and dermis per se without an affiliated moiety. Given that ansin2 lacks unwanted toxicities and immunogenicity, it holds great potential in treating hyperpigmentation in the cosmetics and pharmaceutical industries

Python Cathelicidin CATHPb1 Protects against Multidrug-Resistant Staphylococcal Infections by Antimicrobial-Immunomodulatory Duality

Multidrug-resistant Staphylococcus aureus, including MRSA (methicillin-resistant) and VRSA (vancomycin-resistant), causes serious healthcare-associated infections, even sepsis and death. Here, we identified six novel cathelicidins (CATHPb1–6) from Python bivittatu, and CATHPb1 displayed the best in vitro pharmacological and toxicological profile. We further show that CATHPb1 exhibited evident protection in mice MRSA/VRSA infection models, given either 24 h before or 4 h after infection. The protection was all effective through different administration routes, but was blocked by in vivo depletion of monocyte/macrophages or neutrophils. CATHPb1 can rapidly and massively modulate macrophages/monocytes and neutrophils trafficking to the infection site, and potentiate their bactericidal functions. Meanwhile, CATHPb1 remarkably augmented neutrophil-mediated bacteria killing by facilitating neutrophil extracellular traps (NETs) formation and preventing its degradation. Acting through MAPKs and NF-κB pathways, CATHPb1 selectively enhanced the levels of chemokines while reducing the production of pro-inflammatory cytokines without undesirable toxicities. The much improved serum half-life and stabilities confer CATHPb1 an excellent prospect to become a novel therapeutic agent against multidrug-resistant staphylococcal infections

Remains of trilobites and other species discovered in a volcanic ash bed of the end-Permian, Yangtze craton, South China

<p>The remains of trilobites and other species were unexpectedly discovered in a volcanic ash layer beneath the Permian–Triassic Boundary (PTB). Based on a biostratigraphic investigation of the Zhongliangshan section in Chongqing, South China, the quantity of the species gradually decreased with subsequent volcanism. This finding provides an opportunity to further understand the disappearance of trilobites and the evolution of the mass extinction event. The temporal coincidence between the volcanic eruption event and the loss of trilobites and other species supports the idea of a cause-and-effect relationship. The species remains in the ash bed appeared before the disappearance of <i>Clarkina</i> <i>yini</i> and the climax of the negative carbon isotope excursion, which implies that the onset of the mass extinction occurred at the end-Permian. The explosive volcanic events caused massive releases of CO₂, toxic gases and volcanic ash and resulted in loss of habitat for certain species in the Tethys domain. This phenomenon may have led to the abrupt death of trilobites and the catastrophic collapse of biodiversity.</p

Superconductivity and Signatures of Nontrivial Topology in the Layered Compound Ca₂Pd₃Sb₄

Superconductivity in low-dimensional compounds has attracted considerable interest. In this study, we report a new layered Pd-based type-II superconductor, Ca2Pd3Sb4, which contains CaPd2Sb3 of CaBe2Ge2 blocks and CaPdSb of CeMg2Si2 blocks that are stacked alternately along the crystallographic c axis. The measured electrical resistivity, magnetic susceptibility, and specific heat of the Ca2Pd3Sb4 crystals, which are grown via a self-flux method, consistently demonstrate bulk superconductivity at about 1.30 K. Further analyses of the data indicate strong anisotropic behavior with the parameter γ ∼ 3.8 along the ab plane and c axis. Longitudinal magnetotransport measurements up to ∼18 T reveal notable Shubnikov–de Haas oscillations with a single frequency (F = 462 T), demonstrating the existence of an electron pocket in the Brillouin zone. First-principles calculation reveals that the metallicity of the compound with a quasi-two-dimensional Fermi surface and the d orbitals of Pd and p orbitals of Sb are the main contributors to the total density of states at the Fermi level in Ca2Pd3Sb4