Efficacy of bile acid profiles in diagnosing and staging of alcoholic liver disease

The diagnosis of alcoholic liver disease (ALD) is still a great challenge. Therefore, the purpose of this study is to identify and characterize new metabolomic biomarkers for the diagnosis and staging of ALD. A total of 127 patients with early liver injury, 40 patients with alcoholic cirrhosis (ALC) and 40 healthy controls were included in this study. Patients with early liver injury included 45 patients with alcoholic liver disease (ALD), 40 patients with non-alcoholic fatty liver disease (NAFLD) and 40 patients with viral liver disease (VLD). The differential metabolites in serum samples were analyzed using ultra-high-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry, and partial metabolites in the differential metabolic pathway were identified by liquid chromatography– tandem mass spectrometry. A total of 40 differential metabolites and five differential metabolic pathways in the four groups of patients with early liver disease and healthy controls were found, and the metabolic pathway of primary bile acid (BA) biosynthesis was the pathway that included the most differential metabolites. Therefore, 22 BA profiles were detected. The results revealed that the changes of BA profiles were most pronounced in patients with ALD compared with patients with NAFLD and VLD, in whom 12 differential BAs were diagnostic markers of ALD (AUC = 0.883). The 19 differential BAs in ALC and ALD were diagnostic markers of the stage of alcoholic hepatic fibrosis (AUC = 0.868). BA profiles are potential indicators in the diagnosis of ALD and evaluation of different stages.</p

Ultrathin Carbon-Coated Pt/Carbon Nanotubes: A Highly Durable Electrocatalyst for Oxygen Reduction

Nanostructures constituted of Pt nanoparticles (NPs) supported on carbon materials are considered to be among the most active oxygen reduction reaction (ORR) catalysts for fuel cells. However, in practice, the usage of such ORR catalysts is limited by their insufficient durability caused by the low physical and chemical stability of Pt NPs during the reaction. We herein present a strategy to synthesize highly durable and active electrocatalysts composed of Pt NPs supported on carbon nanotubes (CNTs) and covered with an ultrathin layer of graphitic carbon. Such hybrid ORR catalysts were obtained by an interfacial in situ polymer encapsulation–graphitization method, where a glucose-containing polymer was grown directly on the surface of Pt/CNTs. The thickness of the carbon-coating layer can be precisely tuned between 0.5 nm and several nanometers by simply programming the polymer growth on Pt/CNTs. The resulting Pt/CNTs@C with a carbon layer thickness of ∼0.8 nm (corresponding to ∼2–3 graphene layers) showed high activity, and excellent durability, with no noticeable activity loss, even after 20 000 cycles of accelerated durability tests. These ultrathin carbon coatings not only act as a protective layer to prevent aggregation of Pt NPs but they also lead to better sample dispersion in solvent which are devoid of aggregates, resulting in a better utilization of Pt. We envision that this polymeric nanoencapsulation strategy is a promising technique for the production of highly active and stable ORR catalysts for fuel cells and metal–air batteries

Highly Functional Bioinspired Fe/N/C Oxygen Reduction Reaction Catalysts: Structure-Regulating Oxygen Sorption

Tuna is one of the most rapid and distant swimmers. Its unique gill structure with the porous lamellae promotes fast oxygen exchange that guarantees tuna’s high metabolic and athletic demands. Inspired by this specific structure, we designed and fabricated microporous graphene nanoplatelets (GNPs)-based Fe/N/C electrocatalysts for oxygen reduction reaction (ORR). Careful control of GNP structure leads to the increment of microporosity, which influences the O₂ adsorption positively and desorption oppositely, resulting in enhanced O₂ diffusion, while experiencing reduced ORR kinetics. Working in the cathode of proton-exchange membrane fuel cells, the GNP catalysts require a compromise between adsorption/desorption for effective O₂ exchange, and as a result, appropriate microporosity is needed. In this work, the highest power density, 521 mW·cm^–2, at zero back pressure is achieved

Pt/TiSi_<i>x</i>‑NCNT Novel Janus Nanostructure: A New Type of High-Performance Electrocatalyst

Novel Janus nanostructured electrocatalyst (Pt/TiSi_<i>x</i>-NCNT) was prepared by first sputtering TiSi_<i>x</i> on one side of N-doped carbon nanotubes (NCNTs), followed by wet chemical deposition of Pt nanoparticles (NPs) on the other side. Transmission electron microscopy (TEM) studies showed that the Pt NPs are mainly deposited on the NCNT surface where no TiSi_<i>x</i> (i.e., between the gaps of TiSi_<i>x</i> film). This feature could benefit the increase in the stability of the Pt NP catalyst. Indeed, compared to the state-of-the-art commercial Pt/C catalyst, this novel Pt/TiSi_<i>x</i>-NCNT Janus structure showed ∼3 times increase in stability as well as significantly improved CO tolerance. The obvious performance enhancement could be attributed to the better corrosion resistance of TiSi_<i>x</i> and NCNTs than the carbon black that is used in the commercial Pt/C catalyst. Pt/TiSi_<i>x</i>-NCNT Janus nanostructures open the door for designing new type of high-performance electrocatalyst for fuel cells and other oxygen reduction reaction-related energy devices

3D Porous Fe/N/C Spherical Nanostructures As High-Performance Electrocatalysts for Oxygen Reduction in Both Alkaline and Acidic Media

Exploring inexpensive and high-performance nonprecious metal catalysts (NPMCs) to replace the rare and expensive Pt-based catalyst for the oxygen reduction reaction (ORR) is crucial for future low-temperature fuel cell devices. Herein, we developed a new type of highly efficient 3D porous Fe/N/C electrocatalyst through a simple pyrolysis approach. Our systematic study revealed that the pyrolysis temperature, the surface area, and the Fe content in the catalysts largely affect the ORR performance of the Fe/N/C catalysts, and the optimized parameters have been identified. The optimized Fe/N/C catalyst, with an interconnected hollow and open structure, exhibits one of the highest ORR activity, stability and selectivity in both alkaline and acidic conditions. In 0.1 M KOH, compared to the commercial Pt/C catalyst, the 3D porous Fe/N/C catalyst exhibits ∼6 times better activity (e.g., 1.91 mA cm^–2 for Fe/N/C vs 0.32 mA cm^–2 for Pt/C, at 0.9 V) and excellent stability (e.g., no any decay for Fe/N/C vs 35 mV negative half-wave potential shift for Pt/C, after 10000 cycles test). In 0.5 M H₂SO₄, this catalyst also exhibits comparable activity and better stability comparing to Pt/C catalyst. More importantly, in both alkaline and acidic media (RRDE environment), the as-synthesized Fe/N/C catalyst shows much better stability and methanol tolerance than those of the state-of-the-art commercial Pt/C catalyst. All these make the 3D porous Fe/N/C nanostructure an excellent candidate for non-precious-metal ORR catalyst in metal–air batteries and fuel cells

Chemical Structure of Nitrogen-Doped Graphene with Single Platinum Atoms and Atomic Clusters as a Platform for the PEMFC Electrode

A platform for producing stabilized Pt atoms and clusters through the combination of an N-doped graphene support and atomic layer deposition (ALD) for the Pt catalysts was investigated using transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). It was determined, using imaging and spectroscopy techniques, that a wide range of N-dopant types entered the graphene lattice through covalent bonds without largely damaging its structure. Additionally and most notably, Pt atoms and atomic clusters formed in the absence of nanoparticles. This work provides a new strategy for experimentally producing stable atomic and subnanometer cluster catalysts, which can greatly assist the proton exchange membrane fuel cell (PEMFC) development by producing the ultimate surface area to volume ratio catalyst