Growth of carbon nanotubes over carbon nanofibers catalyzed by bimetallic alloy nanoparticles as a bifunctional electrode for Zn-air batteries.

Design of economical, large-scale, stable, and highly active bifunctional electrocatalysts for Zn-air batteries with enhanced oxygen reduction and oxygen evolution performance is needed. Herein, a series of electrocatalysts were facilely fabricated where in situ formed bimetallic nanoparticles aided in the growth of carbon nanotubes over carbon nanofibers (MM'-CNT@CNF) during thermal treatment. Different combinations of Fe, Ni, Co and Mn metals and melamine as precursor for CNT growth were investigated. The synergistic interaction between bimetallic nanoparticles and N-doped carbon results in greatly improved bifunctional catalytic activity for both oxygen reduction and evolution reactions (ORR, OER) using FeNi-CNT@CNF as catalyst. The half-wave potential (0.80 V vs. RHE) for FeNi-CNT@CNF for ORR was close to that of Pt/C (0.79 V vs. RHE), meanwhile its stability was superior to Pt/C. Likewise, during OER, the FeNi-CNT@CNF reached a current density of 10 mA cm-2 at a rather low overpotential of 310 mV vs. RHE compared to benchmark RuO2 (410 mV). The rechargeable Zn-air prototype battery using FeNi-CNT@CNF as an air electrode outperformed the mixture of Pt/C and RuO2 with discharge/charge overpotential of 0.61 V, power density of 118 mW cm-2 at 10 mA cm-2 and an improved cycling stability over 108 hours.

Theoretical investigation of the optoelectronic response of highly correlated Cu3P photocatalyst.

Photocatalytic materials attract immense scientific interest due to their possible applications in energy harvesting. These applications are strongly dependent on the material's band gap and efficient visible light absorption, which ultimately relies on the underlying electronic structure of the material. In this work, we have theoretically studied the electronic and optical response of a Cu3P semiconductor. We have used Density Functional Theory (DFT), and the Many-Body Perturbation Theory (MBPT) based Bethe-Salpeter Equation (BSE). Cu3P has intriguing band gap nature, as DFT predicts a semi-metallic state which was corrected by employing the Hubbard potentials. Only astronomically large values of Hubbard potentials reproduced the semiconducting state of Cu3P. The optical response of the material is computed within a Random Phase Approximation (RPA) and using the BSE on top of DFT+U wavefunctions and on the ground state computed with the PBE0 functional. The BSE captures the excitonic physics, and the optical absorption obtained from it was red-shifted compared to the RPA, which shows the significance of electron-hole interactions in Cu3P. The comparison of the BSE with experiments suggests that BSE@PBE0 reproduces the optical absorption much more closely to the experimental data.

Extracellular histones are a target in myocardial ischaemia-reperfusion injury.

AIMS: Acute myocardial infarction causes lethal cardiomyocyte injury during ischaemia and reperfusion (I/R). Histones have been described as important Danger Associated Molecular Proteins (DAMPs) in sepsis. The objective of this study was to establish whether extracellular histone release contributes to myocardial infarction. METHODS AND RESULTS: Isolated, perfused rat hearts were subject to I/R. Nucleosomes and histone-H4 release was detected early during reperfusion. Sodium-ß-O-Methyl cellobioside sulfate (mCBS), a newly developed histone-neutralizing compound, significantly reduced infarct size whilst also reducing the detectable levels of histones. Histones were directly toxic to primary adult rat cardiomyocytes in vitro. This was prevented by mCBS or HIPe, a recently described, histone-H4 neutralizing peptide, but not by an inhibitor of TLR4, a receptor previously reported to be involved in DAMP-mediated cytotoxicity. Furthermore, TLR4-reporter HEK293 cells revealed that cytotoxicity of histone H4 was independent of TLR4 and NF-κB. In an in vivo rat model of I/R, HIPe significantly reduced infarct size. CONCLUSION: Histones released from the myocardium are cytotoxic to cardiomyocytes, via a TLR4-independent mechanism. The targeting of extracellular histones provides a novel opportunity to limit cardiomyocyte death during I/R injury of the myocardium.

First-principles study on the electronic and optical properties of Bi2WO6.

Photocatalytic materials attract continued scientific interest due to their possible application in energy harvesting. These applications critically rely on efficient photon absorption and exciton physics, which are governed by the underlying electronic structure. We report the electronic properties and optical response of the Bi2WO6 bulk photocatalyst using first-principle methods. The density functional theory DFT-computed electronic band gap is corrected by including Hubbard potentials for W-5d and O-2p orbitals, and one of the most advanced methods, Quasi-Particle (QP) GW at different levels, with semi-core states of Bi (5s and 5p) and W (4f), carefully taken into account in GW calculations. The perplexing nature of band character of Bi2WO6 is examined, and it comes out to be direct at PBE level without SOC. However, it shows indirect nature at GW level or when Spin-Orbit Coupling (SOC) is turned on even at PBE level. The optical response of the material system is computed within independent-particle approximation (IPA), taking into account local field effects and employing the time-dependent DFT (TDDFT) method. Bethe-Salpeter equation (BSE) is used to capture the excitonic effect, and the results of these approximations are compared with the experimental data. Our first-principle calculations results indicate that electron-hole interaction significantly modifies optical absorption of Bi2WO6, thereby verifying the reported experimental observations.

Role of Caspase 1 in Ischemia/Reperfusion Injury of the Myocardium.

Acute occlusion of a coronary artery can result in myocardial infarction-a leading cause of premature death. Prompt restoration of blood flow to the myocardium can prevent excessive death of cardiomyocytes and improve clinical outcome. Although the major mechanism of cell death after reperfusion is necrosis, it is now recognized that many other cell death pathways may be involved in ischemia-reperfusion (I/R) injury. Pyroptosis is one such cell death pathway that is caspase-1-dependent and induced in response to cellular insult. The activated caspase-1 protease cleaves and activates specific cellular targets including gasdermin D and the proinflammatory cytokines interleukin-1ß and interleukin-18. The N-terminal fragment of gasdermin D forms plasma membrane pores resulting in cytosolic leakage and cell rupture, releasing interleukin-1ß and interleukin-18. Evidence suggests that inflammation induced by I/R through the pyroptotic pathway contributes to cardiomyocyte death, excessive scar formation, and poor ventricular remodeling. For this reason, there is growing interest in targeting components of the pyroptotic pathway as a means of reducing I/R injury.

Electrostatically regulated ternary-doped carbon foams with exposed active sites as metal-free oxygen reduction electrocatalysts.

Pt, a representative electrocatalyst for the oxygen reduction reaction (ORR), has suffered from high cost and poor stability, and thus it is essential to develop alternative electrocatalyst with a high catalytic activity comparable to Pt. Herein, we propose a rationally designed metal-free electrocatalyst with exposed active sites using an N, P, and S ternary-doped and graphene-incorporated porous carbon foam. We developed a novel template-free synthetic approach wherein the electrostatically-mediated complexation of graphene oxide (GO) with 2-aminothiazole (2AT) and branched polyethylenimine (PEI) in the presence of phytic acid (PA) was first induced, followed by a carbonization process to drive the formation of a three-dimensionally interconnected porous carbon foam. The resulting electrocatalyst exhibited a high pore volume and greatly extended specific surface area along with exposed active sites. Benefiting from these properties, the synthesized ternary-doped carbon foam displayed an outstanding electrocatalytic activity for the oxygen reduction ORR through four-electron transfer pathways. We observed that the remarkably improved ORR performance of the synthesized materials manifested an onset and a half-wave potential, mostly close to those of the commercially available ORR electrocatalyst of 20 wt% Pt/C while securing a greater stability in alkaline media.

Mediator- and co-catalyst-free direct Z-scheme composites of Bi2WO6-Cu3P for solar-water splitting.

Exploring new single, active photocatalysts for solar-water splitting is highly desirable to expedite current research on solar-chemical energy conversion. In particular, Z-scheme-based composites (ZBCs) have attracted extensive attention due to their unique charge transfer pathway, broader redox range, and stronger redox power compared to conventional heterostructures. In the present report, we have for the first time explored Cu3P, a new, single photocatalyst for solar-water splitting applications. Moreover, a novel ZBC system composed of Bi2WO6-Cu3P was designed employing a simple method of ball-milling complexation. The synthesized materials were examined and further investigated through various microscopic, spectroscopic, and surface area characterization methods, which have confirmed the successful hybridization between Bi2WO6 and Cu3P and the formation of a ZBC system that shows the ideal position of energy levels for solar-water splitting. Notably, the ZBC composed of Bi2WO6-Cu3P is a mediator- and co-catalyst-free photocatalyst system. The improved photocatalytic efficiency obtained with this system compared to other ZBC systems assisted by mediators and co-catalysts establishes the critical importance of interfacial solid-solid contact and the well-balanced position of energy levels for solar-water splitting. The promising solar-water splitting under optimum composition conditions highlighted the relationship between effective charge separation and composition.

Particle-nested inverse opal structures as hierarchically structured large-scale membranes with tunable separation properties.

A novel multiscale porous architecture where an individual particle is nested inside a hollow chamber of inverse-opal (IO) frame is created using a large scale self-assembly of core-shell structured colloidal particles and subsequent selective removal of the outer shells of the colloids. Since the nested particle is smaller than the size of individual IO chamber, the interconnected nanochannels are spontaneously formed within the structured frame. The size of internal nanochannels is readily tuned to have high permeability and size-selective separation capability, which is successfully tested for nanoparticle separation.