Titanium nitride (TiN) shows desirable properties for use as an electrocatalyst and catalyst support, as it possesses high electrical conductivity and excellent corrosion resistance. However, the effect of oxygen content in the nitride lattice on its ability to drive the hydrogen evolution reaction (HER) is not well understood. Here, a series of titanium oxynitrides (TiNxO1-x) with varied nitrogen occupancy (0.53 ≤ x ≤1.0) in the bulk have been fabricated by ammonolysis. Their specific activities towards the HER were normalised by the surface areas determined by BET and electrochemical methods. We show that the specific activities of these oxynitrides are strongly correlated with the bulk nitrogen occupancy, despite the similar surface composition derived from XPS analysis. Furthermore, a removal of the oxygen content in the bulk or at the surface was attributed to the upgraded performance (up to 25% increase) seen during extended chronoamperometry (CA) tests. Our results show that minimising bulk oxygen content in this class of material is critical to achieve a more conductive and active material for the HER.
Monthly Archives: September 2023
Orange peels and Chlorella vulgaris supplementation ameliorate gamma radiation‐induced oxidative stress by regulating TGF‐β and NOX2/NOX4 signaling pathways
Abstract
Numerous studies revealed that Chlorella vulgaris and orange peels are potential sources for many valuable compounds such as flavonoids, which are natural polyphenols with antioxidant capacities that lessen oxidative stress via suppressing ROS levels. Thus, this study was designed to investigate their radioprotective efficiency either alone or in combination as natural food supplements. Sixty-four male Albino rats were divided into eight groups (n = 8) as follows: control, orange peel (10% in diet), C. vulgaris (1% in diet), orange peel + C. vulgaris, gamma irradiated (2Gy twice per week up to 8Gy), orange peel + gamma irradiation, C. vulgaris + gamma irradiation, and orange peel + C. vulgaris + gamma irradiation. After the experiment, blood serums were collected for biochemical analysis, whole bloods were collected for blood picture, bone marrows were collected for GSH, MDA, TGF-β, NOX2 and NOX4, and liver tissues were collected for histopathological evaluation. Current study revealed that exposure to gamma irradiation induced a significant disturbance in liver function markers (ALT and AST), kidney function markers (urea and creatinine), cholesterol and triglycerides levels in serum. In addition, a significant decrease in WBCs, RBCs, PLT, and Hb in blood of irradiated rats. Moreover, a significant elevation in TGF-β, NOX2, NOX4 activities, and MDA level, while showed a marked decrease in GSH concentration. Furthermore, hepatic inflammation appeared in the histopathological examination. Orange peels or C. vulgaris treatments showed acceptable amelioration in all measured parameters, combination between orange peels and C. vulgaris showed statistically significant additive amelioration in radiation induced disturbance.
[ASAP] Novel Dumbbell-like CeVO4 Carrier-Based Immunochromatographic Assay for Highly Sensitive T-2 Toxin Detection in Food Samples
Analytical Chemistry
DOI: 10.1021/acs.analchem.3c01669
Green Synthesis of 3,4‐Unsubstituted Isoquinolones through Rhodium(III)‐Catalyzed C‒H Activation and Annulation in Ethanol
A mild and convenient synthesis of 3,4-unsubstituted isoquinolones has been achieved from N-methoxybenzamides and vinylene carbonate as an acetylene surrogate with a versatile rhodium(III) catalyst. The reaction proceeded at room temperature in biomass derived ethanol solvent. This protocol avoids the use of stoichiometric external oxidant, as the vinylene carbonate served as the internal oxidant. The C‒H/N‒H activation and annulation manifold proceeded with broad substrate scope and excellent levels of regioselectivities. The preliminary mechanistic studies suggest facile and reversible chelation-assisted C‒H rhodation. Diversification of 3,4-unsubstituted isoquinolones provide access to 4-substituted isoquinolones and 3,4-unsubstituted isoquinolines, which are complementary to the previously reported protocols.
Mechanistic Investigations into the Catalytic Mode of a Dehydratase Complex Involved in the Biosynthesis of Lantibiotic Cacaoidin
Herein, we report that the dehydration process of lantibiotic cacaoidin involves a dehydratase complex, which is composed of a phosphotransferase CaoK and a lyase CaoY in a 1 : 1 molar ratio. We show that fusing CaoK to CaoY enables the resulting enzyme CaoYK to exert enhanced solubility and dehydration activity.
Comprehensive Summary
Dehydration of serine/threonine residues necessitates the activity of a dehydratase enzyme (domain) during the biosynthesis of RiPP. Recently, it was reported that dehydration in the thioviridamide pathway relies on a distinct dehydratase complex that showcases the activities of a phosphotransferase TvaC for serine/threonine phosphorylation and a lyase TvaD for subsequent phosphate elimination. Herein, we report that dehydration reactions in the pathway of lantibiotic cacaoidin involves a similar dehydratase complex, CaoK/CaoY. Remarkably, this dehydratase complex exhibits flexible enzymatic activity and tolerates significant variations in its substrate peptide sequence. By binding with the leader peptide (LP) sequence of precursor peptide CaoA, the dehydration reactions proceed in a directional manner from the C-terminus of the core peptide (CP) to the N-terminus, and C-terminally truncated variants of CP are acceptable. We show that fusing CaoK to CaoY in a 1 : 1 molar ratio enables the resulting enzyme CaoYK to exert enhanced dehydration activity. CaoK binds with the LP to improve its own solubility and to ensure the phosphate transfer activity, while CaoY functions in a manner independently of LP. This work advances our understanding of the dehydration process during cacaoidin formation, and provides useful enzymes and methods for the studies of the rapidly emerging RiPPs.
1H‐Perfluorohexane—An efficient modifier for ethylene tri‐/tetramerization
Synthesis routes and molecular structure of the PNSiP ligand.
Silicon-bridged/N, P (PNSiP) ligand/Cr (III) catalyst system based on different fluorinated hydrocarbons as modifiers have been explored for ethylene selective tri-/tetramerization. Modifiers like 1H-Perfluorohexane (1H-PFH), Hexafluorobenzene (HFB), and Perfluorobiphenyl (PFB) have been proven to show a significant influence on ethylene oligomerization toward 1-hexene and 1-octene of the catalytic system. Among them, 1H-PFH showed the most significant promotion effect in improving activity from 0.95 × 106 g·(mol Cr·h)−1 to as much as 5.66 × 106 g·(mol Cr·h)−1 at high temperature 90°C. Through the analysis of nuclear magnetic resonance (NMR) spectroscopy and ultraviolet visible diffuse reflectance spectroscopy (UV–vis DRS) results, we concluded that 1H-PFH can react with an amount of trimethylaluminum (TMA) contained in the cocatalyst modified methylaluminoxane (MMAO) and the solubility of Cr (III) in solvent can be increased after adding 1H-PFH. Furthermore, the possible reaction routes of 1H-PFH with TMA and MMAO were proposed.
Oxidative dehydrogenation of propane over supported nickel single‐atom catalyst
Comprehensive Summary
Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties, of which overoxidation is the major drawback, with CO and even CO2 as undesired by-products. For the purpose of getting higher propylene selectivity as well as yield, herein we report Ni single atoms supported on calcium aluminate as an efficient catalyst candidate for propane oxidative dehydrogenation. Beneficial from higher valence states of Ni1 species, it shows 2~3 times as much propylene selectivity as that of Ni nanoparticles. About 14.2 % C3H6 yield with 47.3 % propylene selectivity have been achieved on the 2% Ni single atom catalyst and a good stability during 20 h test can be obtained as well.
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Pincer Ligands as Multifunctional Agents for Alzheimer’s Copper Dysregulation and Oxidative Stress: A Computational Evaluation
Alzheimer’s disease (AD) is the most common form of dementia worldwide, affecting millions of people around the globe. AD is characterized by different pathologies being beta-amyloid (Aβ) plaque formation, metal ion dysregulation, and oxidative stress central topics under investigation. Copper-Aβ complexes have been shown to induce catalytic hydrogen peroxide formation and increase OS in the brain leading to neuronal death. Pincer-type compounds are tridentate ligands that coordinate metals in a planar fashion whose properties can be tuned via group substitutions, giving rise to many possibilities in catalysis and drug discovery. In this work we evaluated the potential pharmaceutical activity of 26 pincer compounds in AD’s copper ion-related oxidative stress framework. In this sense, four key aspects were considered: 1) Lipinski’s rule of five, 2) blood-brain barrier permeation, 3) standard reduction potential (SRP) of the formed copper complexes, and 4) the ligand’s affinity towards copper cations. The evaluation of these criteria was performed by means of bioinformatic tools and electronic structure calculations at the DFT level of theory. Our results suggest that two compounds from this set are potential antioxidant agents, whereas five of them are promissory distributor-like compounds in the context of AD.
Sirtuins and autophagy in lipid metabolism
Abstract
Sirtuins are a family of NAD+-dependent deacetylases that regulate some important biological processes, including lipid metabolism and autophagy, through their deacetylase function. Autophagy is a new discovery in the field of lipid metabolism, which may provide a new idea for the regulation of lipid metabolism. There are many tandem parts in the regulation process of lipid metabolism and autophagy of sirtuins protein family. This paper summarized these tandem parts and proposed the possibility of sirtuins regulating lipid autophagy, as well as the interaction and synergy between sirtuins protein family. Currently, some natural drugs have been reported to affect metabolism by regulating sirtuins, some of which regulate autophagy by targeting sirtuins.
Facile construction of alloy‐metal oxide interfaces boosting the one‐pot conversion of methyl levulinate to 1,4‐pentanediol
In this work, a series of N-doped carbon supported FeCo bimetallic catalysts with plentiful FeCo alloy-FeO interfaces, which are derived from metal-organic frameworks (MOFs) ZIF-67, are designed for the one-pot direct conversion of methyl levulinate to 1,4-pentanediol. The FeCo alloy-FeO interfaces are precisely controlled via tuning the reduction temperatures and Fe/Co ratios. The optimal catalyst gives a high 1,4-pentanediol yield of 90.5% along with complete conversion of methyl levulinate. These catalysts are carefully characterized by multiple techniques, such as HRTEM, XRD, XPS, NH3-TPD, Py-IR and so on. It is found that Co presents in electron deficiency caused by the electron transference from Co to Fe in FeCo alloy, which in turn enhances the heterolysis of H2. In addition, plentiful Lewis acid sites derived from interfacial FeO species favour the re-adsorption and the ring-opening reaction of GVL. With the synergy between FeCo alloy and Lewis acid, the FeCo alloy-FeO interfaces exhibit excellent catalytic activity for selective hydrogenation of methyl levulinate to 1,4-pentanediol.