Tuning the Activity and Stability of CoCr-LDH by Forming a Heterostructure on Surface-Oxidized Nickel Foam for Enhanced Water-Splitting Performance

The development of low-cost, efficient catalysts for electrocatalytic water splitting to generate green hydrogen is a hot topic among researchers. Herein, we have developed a highly efficient heterostructure of CoCr-LDH on NiO on nickel foam (NF) for the first time. The preparation strategy follows the simple annealing of a cleaned NF without using any Ni salt precursor, followed by the growth of CoCr-LDH nanosheets over the surface-oxidized NF. The CoCr-LDH/NiO/NF catalyst shows excellent electrocatalytic activity and stability toward oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in a 1 M KOH solution. For OER, only 253 mV and for HER, only 185 mV overpotentials are required to attain a 50 mA cm-2 current density. Also, the long-term stability of both the OER and HER for 60 h proves its robustness. The turnover frequency value for the OER increased 1.85 times after the heterostructure formation compared to bare CoCr-LDH. The calculated Faradaic efficiency values of 97.4 and 94.75% for the OER and HER revealed the high intrinsic activity of the heterostructure. Moreover, the heterostructure only needs 1.57 V of cell voltage when acting as both the anode and the cathode to achieve a 10 mA cm-2 current density. The long-term stability of 60 h for the total water-splitting process proves its excellent performance. Several systematic pre- and post-experiment characterizations prove its durable nature. These excellent OER and HER activities and stabilities are attributed to the surface-modified electronic structure and thin nanosheet-like surface morphology of the heterostructure. The thin, wide, and modified surface of the catalyst facilitates the diffusion of ions (reactants) and gas molecules (products) at the electrode/electrolyte interface. Furthermore, electron transfer from n-type CoCr-LDH to p-type NiO results in enhanced electronic conductivity. This study demonstates the effective design of a self-supported heterostructure with minimal synthetic steps to generate a bifunctional electrocatalyst for water splitting, contributing to the greater cause of green hydrogen economy.

Empowering the Water Oxidation Activity of the Bimetallic Metal-Organic Framework by Annexing Gold Nanoparticles over the Catalytic Surface

Electrocatalytic water splitting to an anodic oxygen evolution reaction (OER) and a cathodic hydrogen evolution reaction (HER) is believed to be the most important application for sustainable hydrogen generation. Being a four-electron, four-proton transfer process, the OER plays the main obstacle for the same. Therefore, designing an effective electrocatalyst to minimize the activation energy barrier for the OER is a research topic of prime importance. The metal-organic framework (MOF) with a highly porous network is considered an appropriate candidate for the OER in alkaline conditions. Apart from several MOFs, the bimetallic one has an advantageous electrocatalytic performance due to the synergistic electronic interaction between two metal ions. However, most bimetallic MOFs have an obstacle to electrocatalytic application due to their low conductive nature, and therefore, they possess a barrier for charge transfer kinetics at the interface. Surface functionalization via various nanoparticles (NPs) is believed to be the most effective strategy for nullifying the conductive issue. In this work, we have designed a CoNi-based bimetallic MOF that was surface-functionalized by Au NPs (Au@CoNi-Bpy-BTC) for the OER under alkaline conditions. Au@CoNi-Bpy-BTC required an overpotential of just 330 mV, which is 56 mV lower as compared to the pristine MOF. Impedance analysis confirms an improved conductivity and charge transfer at the interface, where Au@CoNi-Bpy-BTC possesses a lower Rct value than CoNi-Bpy-BTC materials. Moreover, the Au-decorated MOF shows an 8.5 times increase in the TOF value compared to the pristine MOF. Therefore, this noble strategy toward the surface functionalization of MOFs via noble metal NPs is believed to be the most effective strategy for developing effective electrocatalysts for electrocatalytic application in energy-related fields. Overall, this report displays an exceptional correlation between the decorated NPs over the MOF surface, which can regulate the OER activity, as confirmed by experimental analysis.

Conformation and Affinity Modulations by Multiple Phosphorylation Occurring in the BIN1 SH3 Domain Binding Site of the Tau Protein Proline-Rich Region

An increase in phosphorylation of the Tau protein is associated with Alzheimer's disease (AD) progression through unclear molecular mechanisms. In general, phosphorylation modifies the interaction of intrinsically disordered proteins, such as Tau, with other proteins; however, elucidating the structural basis of this regulation mechanism remains challenging. The bridging integrator-1 gene is an AD genetic determinant whose gene product, BIN1, directly interacts with Tau. The proline-rich motif recognized within a Tau(210-240) peptide by the SH3 domain of BIN1 (BIN1 SH3) is defined as ₂₁₆PTPP₂₁₉, and this interaction is modulated by phosphorylation. Phosphorylation of T217 within the Tau(210-240) peptide led to a 6-fold reduction in the affinity, while single phosphorylation at either T212, T231, or S235 had no effect on the interaction. Nonetheless, combined phosphorylation of T231 and S235 led to a 3-fold reduction in the affinity, although these phosphorylations are not within the BIN1 SH3-bound region of the Tau peptide. Using nuclear magnetic resonance (NMR) spectroscopy, these phosphorylations were shown to affect the local secondary structure and dynamics of the Tau(210-240) peptide. Models of the (un)phosphorylated peptides were obtained from molecular dynamics (MD) simulation validated by experimental data and showed compaction of the phosphorylated peptide due to increased salt bridge formation. This dynamic folding might indirectly impact the BIN1 SH3 binding by a decreased accessibility of the binding site. Regulation of the binding might thus not only be due to local electrostatic or steric effects from phosphorylation but also to the modification of the conformational properties of Tau.

Vacancy Fused Multiple Layers of Copper Sulfoselenide Superstructures: A Propitious HER Electrocatalyst in Acid

The synergistic effect in bi-chalcogenides, an advanced vacancy rich Cu2S-Se@Cu was perceived to be high-efficient and sustainable catalyst towards HER in acid. Interestingly, the selenization of Cu2S@Cu foam creates oxygen...

Effective Formation of a Mn-ZIF-67 Nanofibrous Network via Electrospinning: An Active Electrocatalyst for OER in Alkaline Medium

Finding the active center in a bimetallic zeolite imidazolate framework (ZIF) is highly crucial for the electrocatalytic oxygen evolution reaction (OER). In the present study, we constructed a bimetallic ZIF system with cobalt and manganese metal ions and subjected it to an electrospinning technique for feasible fiber formation. The obtained nanofibers delivered a lower overpotential value of 302 mV at a benchmarking current density of 10 mA cm^-2 in an electrocatalytic OER study under alkaline conditions. The obtained Tafel slope and charge-transfer resistance values were 125 mV dec^-1 and 4 Ω, respectively. The kinetics of the reaction is mainly attributed from the ratio of metals (Co and Mn) present in the catalyst. Jahn-Teller distortion reveals that the electrocatalytic active center on the Mn-incorporated ZIF-67 nanofibers (Mn-ZIF-67-NFs) was found to be Mn³⁺ along with the Mn²⁺ and Co²⁺ ions on the octahedral and tetrahedral sites, respectively, where Co²⁺ ions tend to suppress the distortion, which is well supported by density functional theory analysis, molecular orbital study, and magnetic studies.

Accelerating the Electrocatalytic Performance of NiFe-LDH via Sn Doping toward the Water Oxidation Reaction under Alkaline Condition

To generate green hydrogen by water electrolysis, it is vital to develop highly efficient electrocatalysts for the oxygen evolution reaction (OER). The utilization of various 3d transition metal-based layered double hydroxides (LDHs), especially NiFe-LDH, has gained vast attention for OER under alkaline conditions. However, the lack of a proper electronic structure of the NiFe-LDH and low stability under high-pH conditions limit its large-scale application. To overcome these difficulties, in this study, we constructed an Sn-doped NiFe-LDH material using a simple wet-chemical method. The doping of Sn will synergistically increase the active surface sites of NiFe-LDH. The highly active NiFe-LDH Sn₀._015(M) shows excellent OER activity by requiring an overpotential of 250 mV to drive 10 mA/cm² current density, whereas the bare NiFe-LDH required an overpotential of 295 mV at the same current density. Also, NiFe-LDH Sn₀._015(M) shows excellent long-term stability for 50 h in 1 M KOH and also exhibits a higher TOF value of 0.495 s^-1, which is almost five times higher than that of bare NiFe-LDH. This study highlights Sn doping as an effective strategy for the development of low-cost, effective, stable, self-supported electrocatalysts with a high current density for improved OER and other catalytic applications in the near future.

Stable and Discriminatory Radiomic Features from the Tumor and Its Habitat Associated with Progression-Free Survival in Glioblastoma: A Multi-Institutional Study

BACKGROUND AND PURPOSE

Glioblastoma is an aggressive brain tumor, with no validated prognostic biomarkers for survival before surgical resection. Although recent approaches have demonstrated the prognostic ability of tumor habitat (constituting necrotic core, enhancing lesion, T2/FLAIR hyperintensity subcompartments) derived radiomic features for glioblastoma survival on treatment-naive MR imaging scans, radiomic features are known to be sensitive to MR imaging acquisitions across sites and scanners. In this study, we sought to identify the radiomic features that are both stable across sites and discriminatory of poor and improved progression-free survival in glioblastoma tumors.

MATERIALS AND METHODS

We used 150 treatment-naive glioblastoma MR imaging scans (Gadolinium-T1w, T2w, FLAIR) obtained from 5 sites. For every tumor subcompartment (enhancing tumor, peritumoral FLAIR-hyperintensities, necrosis), a total of 316 three-dimensional radiomic features were extracted. The training cohort constituted studies from 4 sites (n = 93) to select the most stable and discriminatory radiomic features for every tumor subcompartment. These features were used on a hold-out cohort (n = 57) to evaluate their ability to discriminate patients with poor survival from those with improved survival.

RESULTS

Incorporating the most stable and discriminatory features within a linear discriminant analysis classifier yielded areas under the curve of 0.71, 0.73, and 0.76 on the test set for distinguishing poor and improved survival compared with discriminatory features alone (areas under the curve of 0.65, 0.54, 0.62) from the necrotic core, enhancing tumor, and peritumoral T2/FLAIR hyperintensity, respectively.

CONCLUSIONS

Incorporating stable and discriminatory radiomic features extracted from tumors and associated habitats across multisite MR imaging sequences may yield robust prognostic classifiers of patient survival in glioblastoma tumors.

Constructing electrospun spinel NiFe2O4 nanofibers decorated with palladium ions as nanosheets heterostructure: boosting electrocatalytic activity of HER in alkaline water electrolysis

The development of efficient electrocatalysts for the water splitting process and understanding their fundamental catalytic mechanisms are highly essential to achieving high performance in energy conversion technologies. Herein, we have synthesised spinel nickel ferrite nanofibers (NiFe₂O₄-NFs) via an electrospinning (ES) method followed by a carbonization process. The resultant fiber was subjected to electrocatalytic water splitting reactions in alkaline medium. The catalytic efficiency of the NiFe₂O₄-NFs in OER was highly satisfactory. But it is not high enough to catalyse the HER process. Hence, palladium ions were decorated as nanosheets on NiFe₂O₄-NFs as a heterostructure to improve the catalytic efficiency for HER. Density functional theory (DFT) confirms that the addition of palladium to NiFe₂O₄-NFs helps to reduce the effect of catalyst poisoning and improve the efficiency of the catalyst. In an alkaline hybrid electrolyser, the required cell voltage was observed as 1.51 V at a fixed current density of 10 mA cm^-2.

Impact of Chromate and Dichromate on Lysozyme Stability: A Spectroscopic and Molecular Docking Investigation

A comparative study of interaction between Lysozyme (Lyz) with two hexavalent chromate ions; chromate and dichromate; which are prevalently known for their toxicity, was investigated using different spectroscopic techniques along with molecular docking study. Both steady-state and time-resolved studies revealed that the addition of chromate/dichromate is responsible for strong quenching of intrinsic fluorescence in Lyz and the quenching is caused by both static and dynamic quenching mechanism. Different binding and thermodynamic parameters were also calculated at different temperatures from the intrinsic fluorescence of Lyz. The conformational change in Lyz and thermodynamic parameters obtained during the course of interaction with chromate/dichromate were well-supported by the molecular docking results.

Vanadium-Doped Nickel Cobalt Layered Double Hydroxide: A High-Performance Oxygen Evolution Reaction Electrocatalyst in Alkaline Medium

Vast attention from researchers is being given to the development of suitable oxygen evolution reaction (OER) electrocatalysts via water electrolysis. Being highly abundant, the use of transition-metal-based OER catalysts has been attractive more recently. Among the various transition-metal-based electrocatalysts, the use of layered double hydroxides (LDHs) has gained special attention from researchers owing to their high stability under OER conditions. In this work, we have reported the synthesis of trimetallic NiCoV-LDH via a simple wet-chemical method. The synthesized NiCoV-LDH possesses aggregated sheet-like structures and is screened for OER studies in alkaline medium. In the study of OER activity, the as-prepared catalyst demanded 280 mV overpotential and this was 42 mV less than the overpotential essential for pristine NiCo-LDH. Moreover, doping of a third metal into the NiCo-LDH system might lead to an increase in TOF values by almost three times. Apart from this, the electronic structural evaluation confirms that the doping of V³⁺ into NiCo-LDH could synergistically favor the electron transfer among the metal ions, which in turn increases the activity of the prepared catalyst toward the OER.

Revealing the pH-Universal Electrocatalytic Activity of Co-Doped RuO2 toward the Water Oxidation Reaction

Electrocatalytic water splitting has gained vast attention in recent decades for its role in catalyzing hydrogen production effectively as an alternative to fossil fuels. Moreover, the designing of highly efficient oxygen evolution reaction (OER) electrocatalysts across the universal pH conditions was more challengeable as in harsh anodic potentials, it questions the activity and stability of the concerned catalyst. Generally, geometrical engineering and electronic structural modulation of the catalyst can effectively boost the OER activity. Herein, a Co-doped RuO₂ nanorod material is developed and used as an OER electrocatalyst at different pH conditions. Co-RuO₂ exhibits a lower overpotential value of 238 mV in an alkaline environment (1 M KOH) with a Tafel slope value of 48 mV/dec. On the other hand, in acidic, neutral, and near-neutral environments, it required overpotentials of 328, 453, and 470 mV, respectively, to attain a 10 mA/cm² current density. It is observed that doping of Co into the RuO₂ could synergistically increase the active sites with the enhanced electrophilic nature of Ru⁴⁺ to accelerate OER in all of the pH ranges. This study finds the applicability of earth-abundant-based metals like Co to be used in universal pH conditions with a simple doping technique. Further, it assured the stable nature in all pH electrolytes and needs to be further explored with other metals in the future.

Enhancement of the OER Kinetics of the Less-Explored α-MnO2 via Nickel Doping Approaches in Alkaline Medium

Development of a low-cost transition metal-based catalyst for water splitting is of prime importance for generating green hydrogen on an industrial scale. Recently, various transition metal-based oxides, hydroxides, sulfides, and other chalcogenide-based materials have been synthesized for developing a suitable anode material for the oxygen evolution reaction (OER). Among the various transition metal-based catalysts, their oxides have received much consideration for OER, especially in lower pH condition, and MnO₂ is one of the oxides that have widely been used for the same. The large variation in the structural disorder of MnO₂ and internal resistance at the electrode-electrolyte interfaces have limited its large-scale application. By considering the above limitations of MnO₂, here in this work, we have designed Ni-doped MnO₂ via a simple wet-chemical synthetic route, which has been successfully applied for OER application in 0.1 M KOH solution. Doping of various quantities of Ni into the MnO₂ lattices improved the OER properties, and for achieving 10 mA/cm² current density, the Ni-doped MnO₂ containing 0.02 M of Ni²⁺ ions (coined as MnO₂-Ni_0.002(M)) demands only 445 mV overpotential, whereas the bare MnO₂ required 610 mV overpotential. It has been proposed that the incorporation of nickel ions into the MnO₂ lattices leads to an electron transfer from the Ni³⁺ ions to Mn⁴⁺, which in turn facilitates the Jahn-Teller distortion in the Mn-O octahedral unit. This electron transfer and the creation of a structural disorder in the Mn sites result in the improvization of the OER properties of the MnO₂ materials.

Metallic Gold-Incorporated Ni(OH)2 for Enhanced Water Oxidation in an Alkaline Medium: A Simple Wet-Chemical Approach

The development of a highly efficient electrocatalyst for the oxygen evolution reaction (OER) with a lower overpotential and high intrinsic activity is highly challenging owing to its sluggish kinetic behavior. As an alternative to the state-of-the-art OER catalyst, recently, transition-metal-based hydroxide materials have been shown to play important roles for the same. Owing to the high earth abundance of various Ni-based hydroxide and its derivatives, these are known to be highly studied materials for the OER. Herein, we report a simple wet-chemical synthesis of metallic gold-incorporated (by varying the concentration of Au³⁺ ions) Ni(OH)₂ nanosheets as an active and stable electrocatalyst for the OER in 1 M KOH medium. The Au-Ni(OH)₂ (2) catalyst demanded a low overpotential of 288 mV to attain a geometric current density of 10 mA/cm² with a lower Tafel value of 55 mV/dec compared to bare Ni(OH)₂ with a lower mass loading of only 0.1 mg/cm². Tafel slope analysis reveals that the incorporation of metallic gold on the hydroxide surfaces could alter the mechanistic pathways of the overall OER reaction. It has been proposed that the incorporation of metallic gold over the Ni(OH)₂ surfaces led to a change in the electronic structure of the electroactive nickel sites (Jahn-Teller distortion), which favors the OER by electronic aspects.

Advancing the extended roles of 3D transition metal based heterostructures with copious active sites for electrocatalytic water splitting

The replacement of noble metals with alternative electrocatalysts is highly demanded for water splitting. From the exploration of 3D -transition metal based heterostructures, engineering at the nano-level brought more enhancements in active sites with reduced overpotentials for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). However, recent developments in 3D transition metal based heterostructures like direct growth on external substrates (Ni foam, Cu foam) gave highly impressive activities and stabilities. Research needs to be focused on how the active sites can be enhanced further with 3D heterostructures of transition metals by studying them with various counterparts like hydroxides, layered double hydroxides and phosphides for empowering both OER and HER applications. This perspective covers the way to enlarge the utilization of 3D heterostructures successfully in terms of reduced overpotentials, highly exposed active sites, increased electrical conductivity, porosity and high-rate activity. From the various approaches of growth of transition metal based 3D heterostructures, it is easy to fine tune the active sites to have a viable production of hydrogen with less applied energy input. Overall, this perspective outlines a direction to increase the number of active sites on 3D transition metal based heterostructures by growing on 3D foams for enhanced water splitting applications.

Polyethylene glycol perturbs the unfolding of CRABP I: A correlation between experimental and theoretical approach

The importance of macromolecules paves the way towards a detailed molecular level investigation as all most all cellular processes occurring at the interior of cells in the form of proteins, enzymes, and other biological molecules are significantly affected because of their crowding. Thus, exploring the role of crowding environment on the denaturation and renaturation kinetics of protein molecules is of great importance. Here, CRABP I (cellular retinoic acid binding protein I) is employed as a model protein along with different molecular weights of Polyethylene glycol (PEG) as molecular crowders. The experimental evaluations are done by accessing the protein secondary structure analysis using circular dichroism (CD) spectroscopy and unfolding kinetics using intrinsic fluorescence of CRABP I at 37 °C to mimic the in vivo crowding environment. The unfolding kinetics results indicated that both PEG 2000 and PEG 4000 act as stabilizers by retarding the unfolding kinetic rates. Both kinetic and stability outcomes presented the importance of crowding environment on stability and kinetics of CRABP I. The molecular dynamics (MD) studies revealed that thirteen PEG 2000 molecules assembled during the 500 ns simulation, which increases the stability and percentage of β-sheet. The experimental findings are well supported by the molecular dynamics simulation results.

Binding and inhibitory effect of ravidasvir on 3CLpro of SARS-CoV-2: a molecular docking, molecular dynamics and MM/PBSA approach

Drug repurposing requires a limited resource, cost-effective and faster method to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, this in silico studies attempts to identify the drug-likeness properties of ravidasvir, an II/III phase clinical trial chronic hepatitis C drug against 3-Chymotrypsin-like protease (3CL^pro) of SARS-CoV-2 to combat the ongoing coronavirus disease 2019 (COVID-19) pandemic. This protease is predominantly involved in virus replication cycle; hence it is considered as a potent drug target. The molecular docking results showed that ravidasvir was found to be potent inhibitors of 3CL^pro with scoring function based binding energy is -26.7 kJ/mol. Further dynamic behaviour of apo form and complex form of ravidasvir with 3CL^pro were studied using molecular dynamics (MD) simulations over 500 ns each, total 2 µs time scale. The motion of the protein was studied using principal component analysis of the MD simulation trajectories. The binding free energy calculated using MM/PBSA method from the MD simulation trajectory was -190.3 ± 70.2 kJ/mol and -106.0 ± 26.7 kJ/mol for GROMOS96 54A7 and AMBER99SB-ILDN force field, respectively. This in silico studies suggesting ravidasvir might be a potential lead molecule against SARS-CoV-2 for further optimization and drug development to combat the life-threatening COVID-19 pandemic.Communicated by Ramaswamy H. Sarma.

Role of defects and grain boundaries in the thermal response of wafer-scale hBN films

With more widespread applications of nanotechnology, heat dissipation in nanoscale devices is becoming a critical issue. We study the thermal response of wafer-scale hexagonal boron nitride (hBN) layers, which find potential applications as ideal substrates in two dimensional devices. Sapphire-supported thin hBN films, 2'' in size and of different thicknesses, were grown using metalorganic vapour phase epitaxy. These large-scale films exhibit wrinkles defects and grain boundaries over their entire area. The shift of [Formula: see text] phonon mode with temperature is analysed by considering the cumulative contribution of anharmonic phonon decay along with lattice thermal expansion, defect, and strain modulation. The study demonstrates that during heat treatment the strain evolution plays a dominating role in governing the characteristics of the wrinkled thinner films. Interestingly we find that both defects and strain determine the spectral line-width of these wafer-scale films. To the end, from Raman line-width, the changes in phonon lifetime in delaminated and as-grown films is estimated. The results suggest the possibility of a reduction in thermal transport in these wafer-scale films compared to their bulk counterpart.