Role of the Residue Q1919 in Increasing Kinase Activity of G2019S LRRK2 Kinase: A Computational Study

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Role of the Residue Q1919 in Increasing Kinase Activity of G2019S LRRK2 Kinase: A Computational Study

Hydrogen bonding of S1179 with R1077 and E1078 in S1 state and S2 state are responsible for their stability and thus, increase the kinase activity.


Abstract

Mutations in multi-domain leucine-rich repeat kinase 2 (LRRK2) have been an interest to researchers as these mutations are associated with Parkinson's disease. G2019S mutation in LRRK2 kinase domain leads to the formation of additional hydrogen bonds by S2019 which results in stabilization of the active state of the kinase, thereby increasing kinase activity. Two additional hydrogen bonds of S2019 are reported separately. Here, a mechanistic picture of the formation of additional hydrogen bonds of S2019 with Q1919 (also with E1920) is presented using ‘active’ Roco4 kinase as a homology model and its relationship with the stabilization of the ‘active’ G2019S LRRK2 kinase. A conformational flipping of residue Q1919 was found which helped to form stable hydrogen bond with S2019 and made ‘active’ state more stable in G2019S LRRK2. Two different states were found within the ‘active’ kinase with respect to the conformational change (flipping) in Q1919. Two doubly-mutated systems, G2019S/Q1919A and G2019S/E1920 K, were studied separately to check the effect of Q1919 and E1920. For both cases, the stable S2 state was not formed, leading to a decrease in kinase activity. These results indicate that both the additional hydrogen bonds of S2019 (with Q1919 and E1920) are necessary to stabilize the active G2019S LRRK2.

Raman Spectroscopy of Formamidinium‐Based Lead Mixed‐Halide Perovskite Bulk Crystals

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Raman Spectroscopy of Formamidinium-Based Lead Mixed-Halide Perovskite Bulk Crystals

Halide doping in perovskites helps to improve the stability of the structure, which is very important for solar-cell applications. Raman spectroscopy and DFT calculations prove to be a combination of powerful techniques for investigating the structure-property relations of perovskites.


Abstract

In recent years, there has been an impressively fast technological progress in the development of highly efficient lead halide perovskite solar cells. Nonetheless, the stability of perovskite films and associated solar cells remains a source of uncertainty and necessitates sophisticated characterization techniques. Here, we report low- to mid-frequency resonant Raman spectra of formamidinium-based lead mixed-halide perovskites. The assignment of the different Raman lines in the measured spectra is assisted by DFT simulations of the Raman spectra of suitable periodic model systems. An important result of this work is that both experiment and theory point to an increase of the stability of the perovskite structure with increasing chloride doping concentration. In the Raman spectra, this is reflected by the appearance of new lines due to the formation of hydrogen bonds. Thus, higher chloride doping results in less torsional motion and lower asymmetric bending contributing to higher stability. This study yields a solid basis for the interpretation of the Raman spectra of formamidinium-based mixed-halide perovskites, furthering the understanding of the properties of these materials, which is essential for their full exploitation in solar cells.

Enhanced Plasmonic Hot Electron Transfer on Aucore‐Agshell Nanoparticles under Visible‐Light Irradiation

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Enhanced Plasmonic Hot Electron Transfer on Aucore-Agshell Nanoparticles under Visible-Light Irradiation

Plasmonic photocatalysis: A boosting hot-electron-hole separation driven by interfacial contact potential enables high photocatalytic activity on Aucore-Agshell bimetallic nanoparticles towards the four-electron reduction of 4-NTP to 4,4′-DMAB.


Abstract

Plasmonic photocatalysis under visible-light irradiation has long been regarded as a very promising strategy for inducing chemical transformations. However, the efficient utilization of these hot electrons on monometallic nanoparticles to induce chemical reaction remains a challenging subject. Here, we study plasmonic hot electron activity of Aucore-Agshell bimetallic nanoparticles towards the four-electron reduction of 4-nitrothiophenol to 4,4′-dimercaptoazobenzene. Our results show that Aucore-Agshell nanoparticles possess a higher catalytic activity than pure Au and Ag nanoparticles and the photocatalytic transformation is strongly dependent on the thickness of Ag shell. The plasmonic catalytic activity could be explained by a boosting hot-electron-hole separation driven by the contact potential at the bimetallic interface. This work provides new opportunities to enhance the efficient utilization of hot electron for plasmonic photocatalysis reaction.

Effect of Synthetic Methodology on the Physicochemical Attributes and Electrocatalytic Activity of NiAl‐LDHs for the Oxygen Evolution Reaction

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Effect of Synthetic Methodology on the Physicochemical Attributes and Electrocatalytic Activity of NiAl-LDHs for the Oxygen Evolution Reaction

Exfoliated NiAl LDH synthesized by aqueous miscible organic solvent treatment exhibited a lower overpotential and higher current density than its analogues due to more accessible active catalytic sites.


Abstract

Layered double hydroxides (LDHs) are promising materials for oxygen evolution reactions (OERs), a key component of water splitting to produce hydrogen and oxygen via water electrolysis. However, the performance of LDHs can be limited by their low surface area and poor accessibility of active sites. In this work, we synthesized highly exfoliated 2D NiAl-LDHs by aqueous miscible solvent treatment method (AMOST) and compared its electrocatalytic efficiency with its analogue synthesised via slow urea hydrolysis. We demonstrate that the exfoliated 2D LDHs prepared by AMOST method have a higher surface area and more active sites than the crystalline LDHs obtained through urea hydrolysis, resulting in a superior OER activity and efficiency. The exfoliated 2D LDHs required a lower overpotential of 280 mV to reach a current density of 50 mA cm−2 and it also outperformed IrO2, a benchmark OER catalyst, in terms of overpotential and stability. We demonstrate that the physicochemical properties of nanosheets derived from NIAl-LDH-based materials are strongly influenced by the synthetic methodology, which affects the exfoliation degree, surface area and active site density. These factors are crucial for improving the OER catalytic performance of these materials, as shown by our results.

Base Promoted the Synthesis of 4‐Quinolones Fused with Medium‐Sized Rings

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In the presence of cesium carbonate, ynones bearing an ortho-amino group reacted with cyclic β-ketoesters through conjugated addition/carbon-carbon σ-bond cleavage/nucleophilic aromatic substitution tandem reaction to obtain 4-quinolones fused with medium-sized rings in good yields. This is the first example of synthesis of 4-quinolones through base-promoted insertion reactions of carbon-carbon triple bonds into carbon-carbon σ-bonds. Notable features of this program are mild and transition-metal-free reaction conditions.

High entropy Pr‐doped hollow NiFeP nanoflowers inlaid on N‐rGO for efficient and durable electrodes for lithium‐ion batteries and direct borohydride fuel cells

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The selection and design of new electrode materials for energy conversion and storage are critical for improved performance, cost reduction, and mass manufacturing. A bifunctional anode with high catalytic activity and extended cycle stability is crucial for rechargeable lithium-ion batteries and direct borohydride fuel cells. Herein, a high entropy novel three-dimensional structured electrode with Pr-doped hollow NiFeP nanoflowers inlaid on N-rGO was prepared via a simple hydrothermal and self-assembly process. For optimization of Pr content, three (0.1, 0.5, and 0.8) different doping ratios were investigated. A lithium-ion battery assembled with NiPr0.5FeP/N-rGO electrode achieved an outstanding specific capacity of 1618.81 mAh g−1 at 200 mA g−1 after 100 cycles with 99.3% Coulombic efficiencies. A prolonged cycling stability of 1025.49 mAh g−1 was maintained even after 1000 cycles at 500 mA g−1. In addition, a full cell battery with NiPr0.5FeP/N-rGO ∥ LCO (Lithium cobalt oxide) delivered a promising cycling performance of 525.8 mAh g−1 after 200 cycles at 150 mA g−1. Subsequently, the NiPr0.5FeP/N-rGO electrode in a direct borohydride fuel cell showed the highest peak power density of 93.70 mW cm−2 at 60 °C. Therefore, this work can be extended to develop advanced electrode for next-generation energy storage and conversion systems.