A review on recent advances in hierarchically porous metal and metal oxide nanostructures as electrode materials for supercapacitors and non-enzymatic glucose sensors

The remarkable significance of electrode materials in industrial processes, energy, sustainability and diabetes monitoring has captivated scientists to develop advance nanomaterials for the benefit of life across the globe. Here in, the recent developments in nanostructured porous metal and metal oxide composite materials for supercapacitor applications and non-enzymatic glucose sensors (NEGS) has been extensively discussed. The essential and active electrode materials from the research and application perspective has been emphasized in detail. We have also evaluated the worthiness, taxonomical classification, efficiency, specific capacitance and sensitivity of these materials for the aforementioned potential applications. Eventually, we concluded the review by providing the aspect ratio, surface morphology, particle size and specific surface area of these materials that plays an indispensable role for their promising potential applications.     

Image Processing and ‘Noise Removal Algorithms’—The Pdes and Their Invariance Properties & Conservation Laws

We analyse the symmetry, invariance properties and conservation laws of the partial differential equations (pdes) and minimization problems (variational functionals) that arise in the analyses of some noise removal algorithms.     

Controlled Assembly of Cu/Co-Oxide Beaded Nanoclusters on Thiolated Graphene Oxide Nanosheets for High-Performance Oxygen Evolution Catalysts

The use of water splitting modules is highly desired for the sustainable production of H₂ as a future energy carrier. However, the sluggish kinetics and demand of high anodic potential are the bottlenecks for half-the cell oxygen evolution reaction (OER), which severely hamper the overall conversion efficiency. Although transition metal oxides based electrocatalysts have been envisioned as cost-effective and potential contenders for this quest, nevertheless, their low conductivity, instability, and limited number of active sites are among the common impediments that need to be addressed to eventually enhance their inherent catalytic potential for enhanced OER activity. Herein, the controlled assembly of transition metal oxides, that is, Cu@CuO_x nanoclusters (NCs, ≈2 nm) and Co@CoO_x beaded nanoclusters (BNCs, ≈2 nm), on thiol-functionalized graphene oxide (G-SH) nanosheets is reported to form novel and highly efficient electrocatalysts for OER. The thiol (-SH) functionality was incorporated by selective epoxidation on the surface of graphene oxide (GO) to achieve chemically exfoliated nanosheets to enhance its conductivity and trapping ability for metal oxides in nanoscale dimensions (≈2 nm). During the electrocatalytic reaction, overpotentials of 290 mV and 310 mV are required to achieve a current density of 10 mA cm⁻² for BNCs and NCs, respectively, and the catalysts exhibit tremendous long-term stability (≈50 h) in purified alkaline medium (1 m KOH) with no dissolution in the electrolyte. Moreover, the smaller Tafel slopes (54 mV/dec for BNCs and 66 mV/dec for NCs), and a Faradic efficiency of approximately 96 % indicate not only the selectivity but also the tailored heterogeneous electrons transfer (HET) rate, which is required for fast electrode kinetics. It is anticipated that such ultrasmall metal oxide nanoclusters and their controlled assembly on a conducting surface (G-SH) may offer high electrochemical accessibility and a plethora of active sites owing to the drastic decrease in dimensions and thus can synergistically ameliorate the challenging OER process.     

Synthesis and photocatalytic properties of α-Fe2O3 nanoellipsoids

A simple and a novel chemical approach was used for the growth of α-Fe₂O₃ nanostructures. Field emission scanning electron microscopy analysis revealed the monodisperse nanoellipsoid morphology of α-Fe₂O₃ nanostructures. The sizes of the short axis and the long axis of these ellipsoids were in the ranges of 50–60 nm and 40–50 nm, respectively. XRD analysis revealed that the product exhibited α-Fe₂O₃ phase. Comprehensive TEM and HRTEM analysis revealed that α-Fe₂O₃ nanoellipsoids are single crystal in nature. The methylene blue decomposition kinetics was studied for different irradiation time. The methylene blue was totally decomposed by increasing the irradiation time up to 220 min.     

Unravelling the effect of temperature on viscosity-sensitive fluorescent molecular rotors

Viscosity and temperature variations in the microscopic world are of paramount importance for diffusion and reactions. Consequently, a plethora of fluorescent probes have evolved over the years to enable fluorescent imaging of both parameters in biological cells. However, the simultaneous effect of both temperature and viscosity on the photophysical behavior of fluorophores is rarely considered, yet unavoidable variations in temperature can lead to significant errors in the readout of viscosity and vice versa. Here we examine the effect of temperature on the photophysical behavior of three classes of viscosity-sensitive fluorophores termed ‘molecular rotors’. For each of the fluorophores we decouple the effect of temperature from the effect of viscosity. In the case of the conjugated porphyrin dimer, we demonstrate that, uniquely, simultaneous dual-mode lifetime and intensity measurements of this fluorophore can be used for measuring both viscosity and temperature concurrently.     

Novel Nano‐sized bis‐indoline Derivatives as Antitumor Agents

A facile access to novel bis‐(indoline‐2,3‐dione) was achieved via reactions of isatin with 1,3‐dibromopropane. The utility of the versatile bis‐(indoline‐2,3‐dione) in the design of new multifunctional building blocks using condensation with hydrazine derivatives was demonstrated. Moreover, a new series of bis‐thiazoles and bis‐thiazol‐4(5H)‐ones were synthesized by the reaction of bis‐thiosemicarbazone derivative with various derivatives of hydrazonoyl halides. The calculations derived from X‐ray diffraction patterns indicated the nanosize of the newly designed compounds. The spectral data of the formed compounds were established their structures. Also, the cytotoxic activity of the produced derivatives was screened against line MCF‐7 (breast cancer cell). It was found that four derivatives from nine investigated compounds showed activity more potent than the standard drug used by 20 times in some cases.     

A templateless surfactant-free seedless aqueous route to single-crystalline ZnO nanowires synthesis

Zinc oxide (ZnO) nanowires (NWs) have been synthesized using zinc nitrate and hexamethylenetetramine by templateless, surfactant-free and seedless aqueous solution route. The morphology of ZnO NWs was considerably affected by growth time: a longer reaction time results in the formation of ZnO NWs. Structural analysis of the synthesized NWs showed an average diameter of 20–30 nm length of several micrometers and single-crystalline wurtzite hexagonal structure. Photoluminescence studies of ZnO NWs showed a strong green emission peak at 585 nm.     

A Molecular Rotor that Measures Dynamic Changes of Lipid Bilayer Viscosity Caused by Oxidative Stress

Oxidation of cellular structures is typically an undesirable process that can be a hallmark of certain diseases. On the other hand, photooxidation is a necessary step of photodynamic therapy (PDT), a cancer treatment causing cell death upon light irradiation. Here, the effect of photooxidation on the microscopic viscosity of model lipid bilayers constructed of 1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine has been studied. A molecular rotor has been employed that displays a viscosity‐dependent fluorescence lifetime as a quantitative probe of the bilayer's viscosity. Thus, spatially‐resolved viscosity maps of lipid photooxidation in giant unilamellar vesicles (GUVs) were obtained, testing the effect of the positioning of the oxidant relative to the rotor in the bilayer. It was found that PDT has a strong impact on viscoelastic properties of lipid bilayers, which ‘travels’ through the bilayer to areas that have not been irradiated directly. A dramatic difference in viscoelastic properties of oxidized GUVs by Type I (electron transfer) and Type II (singlet oxygen‐based) photosensitisers was also detected.