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The intraplate stress field distribution is estimated by considering the isotropic elastic properties of the Indian plate using numerical analysis. In most modelling, the intraplate stresses are typically established on applying plate-driving forces to a homogeneous elastic plate. However, a tectonic plate comprises continental and oceanic lithosphere with sedimentary basins, cratons, and fold belts with varying significant differences in elastic properties, which likely affect the magnitude and pattern of stress and deformation. In the present study, the finite element method (FEM)-based software packages ABAQUS is used to simulate the intraplate stress distribution in the plate using a 3D mechanical model incorporating the elastic properties of the 19 geological regions of the Indian subcontinent and oceanic region. FEM models are validated with Indian plate fixed GPS velocities and found to be in reasonable agreement with the plate’s velocity. This study can augment the interpretability of seismic and geological studies. Also, the model can be helpful to perform seismic hazard assessment (using the stress estimated with the FEM model), identify the seismically active zones and collect insight on active intraplate deformation of seismically active regions of the Indian plate by interpreting the strain rate, deformation rate and stress distribution data.

The examination of graphitic carbon nitride (GCN) synthesis and its catalytic activity in hydrogen production from potassium formate was done as a function of the precursor selection. Four different precursors were assessed, namely urea, dicyandiamide, melamine and thiourea. The catalytic activity of the catalysts fabricated from different GCN precursors and palladium (Pd) was compared. The catalyst prepared from dicyandiamide, Pd-GCN(D), was found to be the most active of the four precursors tested during the first reaction cycle. Nonetheless, the catalyst prepared from urea, Pd-GCN(U), has been attributed by us as the preferred catalyst due to its excellent catalytic activity as well as its phenomenal stability over multiple cycles, which was not observed for the other three catalysts. The better catalytic activity of Pd-GCN(U) is correlated to the high surface area and pore volume of the material. Both the GCN and Pd-GCN samples were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, Brunauer-Emmett-Teller methods, scanning tunneling electron microscopy, and X-ray photoelectron spectroscopy.

In the present study, the emphasis is made on the seismic performance of nuclear containment constructed on layered medium to dense silty sand soil considering the nonlinearity of the containment structure using the concrete damage plasticity (CDP) model and Drucker–Prager plastic model for soil. The finite element model is prepared using the ABAQUS. From the static pushover analysis, it is noticed that yielding force is reduced up to 8.37% and 2.37% in the case of with and without embedment, respectively, as compared to a fixed base. Furthermore, incremental dynamic analysis is performed for the motion range of 0.1 g to 0.6 g, corresponding to the fundamental frequency. For the dynamic analysis, Kelvin element is used at boundaries to incorporate the truncated soil mass. The results are shown in the form of base shear, base moment and displacement ductility, drift ratio, normalized peak settlement, and normalized peak foundation sliding. Moment demand is reduced up to 25.89% and 51.31% in the case of with and without embedment, respectively, as compared to a fixed base. Similarly, base shear demand is increased up to 21.85% in the case of with embedment. It may reduce up to 29.08% in the case of without embedment of foundation as compared to a fixed base. Drift demand of nuclear power plant (NPP) structure is increased up to 14.47% and 38.16% in the case of with and without embedment of foundation, respectively, as compared to a fixed base. In contrast, displacement ductility demand reduced up to 47.95% and 57.52% in the case of with and without embedment of foundation, respectively. Settlement demand is increased linearly in the case of with embedment with respect to ground motion intensity; however, it increases sharply for ground motion intensity > 0.3 g in the case of without embedment. The sliding demand of foundation increase with a low and fixed amount of sliding is examined in the condition of with embedment case; however, it rises steeply in the case of without embedment case, indicating that without considering the embedment effect may increase the design requirement and therefore lead to uneconomical designing. The effect of the CDP model shows the need to consider the nonlinearity of structure along with the nonlinearity of soil.

The selective hydrogenation of a chemical functionality in the presence of other groups is an excellent strategy to avoid multiple synthetic steps. Earth abundant Ni metal supported on graphitic carbon nitride (NiO–Ni/GCN) has been explored as a mild catalyst for the selective reduction of carbonyl compounds. Sodium hypophosphite (NaH2PO2) is used as a hydrogen donor for transfer hydrogenation of aldehydes and ketones. In the presence of NaH2PO2the NiO nanoparticles are in-situ reduced to catalytically active Ni(0) catalyst. NiO–Ni/GCN catalyst has been characterized by various techniques such as PXRD, IR, SEM, TEM, XPS, and TGA etc. In addition, nickel is a cost-effective and earth abundant metal which makes Ni-GCN as a viable hydrogenation catalyst. In contrast to Pd-GCN and Ru-GCN the present catalyst does not lead to hydrodehalogenation of haloaryl compounds in the presence of a hydrogen donor. Moreover, the catalyst is recyclable and can run efficiently for the multiple cycles without significant loss of activity.

In recent years, hydrogen has been considered a promising energy carrier for a sustainable energy economy in the future. An easy solution for the safer storage of hydrogen is challenging and efficient methods are still being explored in this direction. Despite having some progress in this area, no cost-effective and easily applicable solutions that fulfill the requirements of industry are yet to be claimed. Currently, the storage of hydrogen is largely limited to high-pressure compression and liquefaction or in the form of metal hydrides. Formic acid is a good source of hydrogen that also generates CO2 along with hydrogen on decomposition. Moreover, the hydrogenation of CO2 is thermodynamically unfavorable and requires high energy input. Alkali metal formates are alternative mild and noncorrosive sources of hydrogen. On decomposition, these metal formates release hydrogen and generate bicarbonates. The generated bicarbonates can be catalytically charged back to alkali formates under optimized hydrogen pressure. Hence, the formate-bicarbonate-based systems being carbon neutral at ambient condition has certain advantages over formic acid. The formate-bicarbonate cycle can be considered as a vehicle for hydrogen and energy storage. The whole process is carbon-neutral, reversible, and sustainable. This Review emphasizes the various catalytic systems employed for reversible formate-bicarbonate conversion. Moreover, a mechanistic investigation, the effect of temperature, pH, kinetics of reversible formate-bicarbonate conversion, and new insights in the field are also discussed in detail.

Chemiresistive sensors, which are based on semiconducting materials, offer real-time monitoring of environment. However, detection of nonpolar chemical substances is often challenging because of the weakness of the doping effect. Herein, we report a concept of combining a cascade reaction (CR) and a chemiresistive sensor array for sensitive and selective detection of a target analyte (herein, ethylene in air). Ethylene was converted to acetaldehyde through a Pd-catalyzed heterogeneous Wacker reaction at 40 °C, followed by condensation with hydroxylamine hydrochloride to emit HCl vapor. HCl works as a strong dopant for single-walled carbon nanotubes (SWCNTs), enabling the main sensor to detect ethylene with excellent sensitivity (10.9% ppm-1) and limit of detection (0.2 ppm) in 5 min. False responses that occur in the main sensor are easily discriminated by reference sensors that partially employ CR. Moreover, though the sensor monitors the variation of normalized electric resistance (ΔR/R0) in the SWCNT network, temporary deactivation of CR yields a sensor system that does not require analyte-free air for a baseline correction (i.e., estimation of R0) and recovery of response. The concept presented here is generally applicable and offers a solution for several issues that are inherently present in chemiresistive sensing systems.

Microplastics are an emerging threat and a big challenge for the environment. The presence of microplastics (MPs) in water is life-threatening to diverse organisms of aquatic ecosystems. Hence, the scientific community is exploring deeper to find treatment and removal options of MPs. Various physical, chemical and biological methods are researched for MPs removal, among which few have shown good efficiency in the laboratory. These methods also have a few limitations in environmental conditions. Other than finding a suitable method, the creation of legal restrictions at a governmental level by imposing policies against MPs is still a daunting task in many countries. This review is an effort to place all effectual MP removal methods in one document to compare the mechanisms, efficiency, advantages, and disadvantages and find the best solution. Further, it also discusses the policies and regulations available in different countries to design an effective global policy. Efforts are also made to discuss the research gaps, recent advancements, and insights in the field.

The development of green and sustainable transfer hydrogenation protocols without the use of expensive noble metals and toxic solvents is a challenging task. Herein, a highly stable, low-cost, metal-free heterogeneous catalyst, oxidized graphitic carbon nitride (O-GCN), has been developed, which exhibits efficient catalytic hydrogen transfer reactions of carbonyl compounds to corresponding alcohols under mild reaction conditions. The heterogeneous catalyst was synthesized by the chemical oxidation of graphitic carbon nitride (GCN) nanosheets, which results in the generation of carboxyl, hydroxyl and ketone groups over the GCN surface. These hydrophilic groups functionalized on the surface of O-GCN nanosheets act as catalytically active sites for the hydrogen transfer reactions of carbonyl compounds. A wide range of substrates was investigated for the hydrogen transfer reactions using 2-propanol both as a hydrogen donor and a solvent. The O-GCN nanosheets resulted in high yields and high turnover numbers (TON) demonstrating the versatile catalytic potential of the as-synthesized catalyst. The detailed optimization of the reaction parameters (temperature, time and catalyst amount) was performed, in addition to the calculation of green metric parameters. Moreover, the catalyst could be easily recovered and was used for five runs without any significant loss in catalytic activity. This study provides a green, sustainable, attractive, and useful methodology for the hydrogen transfer reactions of a wide range of carbonyl compounds.

The emerging concept of two dimensional (2D) hybrid materials with large surface area and good interfacial contacts is highly desirable for diverse catalytic applications. Herein, we have designed and developed novel 1D-2D nanocomposite by loading manganese dioxide (MnO2) nanorods over reduced graphene oxide (RGO) nanosheets by facile hydrothermal synthesis method to exploit the large surface area, close contact of 1D-2D components with abundant reaction sites. The as prepared MnO2-RGO nanocomposite has been characterized in detail using state-of-art techniques and has been successfully utilized efficient adsorptive photocatalysts for the removal of a colored dye (neutral red) and a colorless pollutant (ciprofloxacin) from water. In addition, the stability and recyclability of this catalyst has also been demonstrated. This work is expected to pave way for the development of many new 1D-2D binary nanocomposite catalysts for environmental remediation applications.

Correction for ‘Sulfonated graphitic carbon nitride as a highly selective and efficient heterogeneous catalyst for the conversion of biomass-derived saccharides to 5-hydroxymethylfurfural in green solvents’ by Tripti Chhabra, et al., Green Chem., 2019, 21, 6012–6026.

Functionalization of the widely known graphitic carbon nitride (GCN) material has been performed, and a novel heterogeneous catalyst is reported by incorporating palladium over the surface of functionalized GCN. GCN was functionalized using an optimized ratio of sulfuric acid, nitric acid, and hydrogen peroxide. The developed catalyst was characterized by powder X-ray diffraction, IR, scanning tunneling microscopy, tunneling electron microscopy, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller, thermogravimetric analysis, and solid-state CP-NMR. The developed material containing ≤1% Pd exhibits superior catalytic activity in comparison to other carbon support materials (such as 5% Pd/C) for various hydrogenation reactions under mild conditions. Potassium formate has been chosen as the best hydrogen source among other alkali metal formates. The developed catalyst was also able to catalyze a one-pot three-step reaction for the synthesis of N-benzylaniline which is a precursor of various antihistamine and anticholargenic drugs. Moreover, the catalyst could be recycled multiple times and consistent activity was reported.

A nanocomposite of potassium-functionalized graphitic carbon nitride (KGCN) and reduced graphene oxide (RGO) was fabricated by a facile hydrothermal method and used as a heterogeneous catalyst for ...

In this study, an effort has been made to perform seismic hazard analysis (SHA) for the state of Assam, considering earthquake catalog collected since 1761–2015 using PSHA and DSHA methods at bed r...

A nanocomposite comprising of MoS2-RGO having unique structural features was developed by using a facile preparation strategy and demonstrated to be a highly efficient heterogeneous catalyst for the synthesis of indole alkaloids in water. The catalyst could be recycled six times without significant loss of its activity. Green chemistry matrices calculations for the reaction showed high atom economy (A.E. = 94.7%) and small E-factor (0.089). Using this nanocomposite as catalyst, four naturally occurring indole alkaloid, namely Arundine, Vibrindole A, Turbomycin B and Trisindole, were synthesized along with their other derivatives in excellent yields.

In the field of biomedicine, upconversion nanoparticles have wide ranging applications from bioimaging to targeted cargo delivery, especially due to their excellent chemical and optical properties in comparison with conventional fluorophores. However, their use in biomedical applications is largely hindered due to strong absorption of short wavelength (

In recent years chemical and biological interest in Turbomycin B and its various analogues have motivated researchers to develop new bioactive indole scaffolds. In this work, we focused on the development of indole alkaloids, especially bioindolemethane derivatives and their anticancer potential. Based on the excellent IC50 value against HeLa and A549 cell, cyano-substituted Turbomycin B (CN-TBM) was selected to understand the mechanism behind cancer cell death. The potential targets involved in CN-TBM mediated apoptotic cell death were predicted by comparing the results of two chemoinformatic approaches, i.e., PharmMapper and IdTarget. Four targets were predicted using these tools and the targets were further subjected to molecular docking to obtain a single target for CN-TBM. Serine/threonine-protein kinase (Pim-1) was identified as the direct target of CN-TBM with a pharmacophore model complementing well with the molecular features of CN-TBM. The interaction between CN-TBM and Pim-1 was well supported by high fit-score, Z-score, idTarget dock score and excellent binding affinity. Further, the present study also provides an insight into co-expression, shared protein domains, functional annotation and relationship within the ten putative targets of CN-TBM predicted by PharmMapper.

Graphene–semiconductor photocatalysts are of utmost interest for achieving visible light activity but there is ambiguity about the role played by graphene in these photocatalysts. Such photocatalysts exhibit both adsorptive and photocatalytic activities towards pollutant degradation. Herein, we report nitrogen doped CaTiO3 (NCT) perovskite coupled with reduced graphene oxide (RGO), RGO–NCT, composites for the first time and utilize them for environmental remediation as an efficient adsorptive photocatalyst. The adsorption and photocatalytic activity were evaluated by investigating the adsorption/degradation of a model dye, methylene blue (MB). In comparison with bare CT and NCT, the RGO–NCT composites exhibit enhanced photocatalytic activity, which could be attributed to the synergistic effect of the adsorption of dye molecules on the RGO surface followed by their degradation under visible light irradiation. In the degradation mechanism, we propose that the degradation of MB is not only due to the dye photosensitization process but also involves the true photocatalytic action of the RGO–NCT composites. The clear role of graphene as an electron acceptor is demonstrated by photoluminescence spectroscopic study. Also, the degradation of a colorless pollutant thiabendazole (TBZ) under visible light irradiation supports our hypothesis. In addition, the commendable stability and recyclability of RGO–NCT photocatalysts demonstrates that these materials can be used as potential, viable and stable photocatalysts for environmental remediation. In principle, we anticipate that our work paves the way for tailoring the photocatalytic activity of perovskite-type semiconductor materials by coupling with graphene for the design of recyclable bifunctional photocatalysts.

Amorphous titania matrix impregnated with Ag nanoparticles has been synthesised based on a facile colloidal synthesis route and has been explored for visible- and sunlight-activated photocatalytic applications. The photocatalytic activity of the material under visible light and sunlight irradiation was demonstrated by investigations on the degradation of a common pollutant, nitrobenzene. In comparison to other TiO2-based nanomaterials, this amorphous titania impregnated with Ag nanoparticles was found to be highly efficient for visible light as well as sunlight-active photocatalytic applications. The superior catalytic activity could be attributed to the efficient charge separation and lessened recombination of the photo-generated electrons and holes at the Ag–titania interface and the presence of multiple metal–metal oxide interfaces due to dispersed impregnation of Ag nanoparticles on amorphous titania matrix. Also, it was found that the photocatalytic activity of the prepared nanocomposites had...

An aberrant reaction of Grignard reagents with N-alkylated indole-3-carboxaldehyde has been observed. Contrary to the usual formation of an alcohol, it afforded an unusual bis(indolyl)methane product. A systematic study on this new mode of reactivity and its application to a synthesis of the potent antibiotic turbomycin B and vibrindole A derivatives is reported.

A conceptually new dimethyl sulfoxide (DMSO) based oxidation process without the use of any activator has been demonstrated for the oxidation of active methylenes and benzhydrols. The developed protocol utilizes the electrophilic center of DMSO for oxidation, which was unexplored before. Mechanistic investigation has confirmed that the source of oxygen is DMSO.

In the pursuit towards the use of sunlight as a sustainable source for energy generation and environmental remediation, photocatalytic water splitting and photocatalytic pollutant degradation have recently gained significant importance. Research in this field is aimed at solving the global energy crisis and environmental issues in an ecologically-friendly way by using two of the most abundant natural resources, namely sunlight and water. Over the past few years, carbon-based nanocomposites, particularly graphene and graphitic carbon nitride, have attracted much attention as interesting materials in this field. Due to their unique chemical and physical properties, carbon-based nanocomposites have made a substantial contribution towards the generation of clean, renewable and viable forms of energy from light-based water splitting and pollutant removal. This review article provides a comprehensive overview of the recent research progress in the field of energy generation and environmental remediation using two-dimensional carbon-based nanocomposites. It begins with a brief introduction to the field, basic principles of photocatalytic water splitting for energy generation and environmental remediation, followed by the properties of carbon-based nanocomposites. Then, the development of various graphene-based nanocomposites for the above-mentioned applications is presented, wherein graphene plays different roles, including electron acceptor/transporter, cocatalyst, photocatalyst and photosensitizer. Subsequently, the development of different graphitic carbon nitride-based nanocomposites as photocatalysts for energy and environmental applications is discussed in detail. This review concludes by highlighting the advantages and challenges involved in the use of two-dimensional carbon-based nanocomposites for photocatalysis. Finally, the future perspectives of research in this field are also briefly mentioned.

Correction for ‘Sulfonated graphitic carbon nitride as a highly selective and efficient heterogeneous catalyst for the conversion of biomass-derived saccharides to 5-hydroxymethylfurfural in green solvents’ by Tripti Chhabra, et al., Green Chem., 2019, 21, 6012–6026.

An environmentally benign, step economical synthesis of ketones directly from aldehydes has been developed using hypervalent iodine as an oxidant. The key features of this protocol are its mild conditions without the use of any heavy and toxic metals for the synthesis of a wide range of ketones.

Dip catalysts suitable for catalyzing important chemical reactions are designed based on bioinspiration principles and are fabricated using a facile soft lithography technique. Specifically, in this work, leaves from two different plants, Gladiolus dalenii and Amaryllis belladonna are chosen, due to their contrasting surface topographical features. The surface microstructures of these two leaves are replicated on a polymer in order to prepare scaffolds for the fabrication of dip catalysts. The microstructures of these scaffolds are utilized to direct the self-assembly of Pd nanoparticles according to the surface topographical features. A thin film of polyvinyl alcohol is used to lock the nanoparticles on the surface and prevent them from leaching. The fabricated bioinspired dip catalysts are thoroughly characterized and are demonstrated to be highly efficient for Suzuki–Miyaura cross-coupling reactions, examined under different experimental conditions. These bioinspired dip catalysts' performance is evaluated based on the percentage yields of the reaction and is correlated with the corresponding surface topographical features to understand the effect of the scaffold architecture on the performance of the catalysts. The developed strategy can be easily adopted to fabricate many more dip catalysts, with intriguing surface features, suitable for catalyzing several other chemical reactions as well.

An environmentally benign, step economical synthesis of ketones directly from aldehydes has been developed using hypervalent iodine as an oxidant. The key features of this protocol are its mild conditions without the use of any heavy and toxic metals for the synthesis of a wide range of ketones.

This work presents a novel approach of using natural plant leaf surfaces having intricate hierarchical structures as scaffolds for Pd nanoparticles and demonstrated it as a Green dip catalyst for Suzuki-Miyaura coupling reactions in water. The influence of the topographical texture of the plant leaves on the deposition and catalytic properties of Pd nanoparticles are presented and discussed. The catalytic activity can be correlated to the surface texture of the leaves, wherein it has been found that the micro/nanostructures present on the surface strongly influence the assembly and entrapment of the nanoparticles, and thereby control aggregation and leaching of the catalysts. This approach can provide insights for the future design and fabrication of bioinspired supports for catalysis, based on replication of leaf surfaces.

Biological matters have been in continuous encounter with extreme environmental conditions leading to their evolution over millions of years. The fittest have survived through continuous evolution, an ongoing process. Biological surfaces are the important active interfaces between biological matters and the environment, and have been evolving over time to a higher state of intelligent functionality. Bioinspired surfaces with special functionalities have grabbed attention in materials research in the recent times. The microstructures and mechanisms behind these functional biological surfaces with interesting properties have inspired scientists to create artificial materials and surfaces which possess the properties equivalent to their counterparts. In this review, we have described the interplay between unique multiscale (micro- and nano-scale) structures of biological surfaces with intrinsic material properties which have inspired researchers to achieve the desired wettability and functionalities. Inspired by naturally occurring surfaces, researchers have designed and fabricated novel interfacial materials with versatile functionalities and wettability, such as superantiwetting surfaces (superhydrophobic and superoleophobic), omniphobic, switching wettability and water collecting surfaces. These strategies collectively enable functional surfaces to be utilized in different applications such as fog harvesting, surface-enhanced Raman spectroscopy (SERS), catalysis, sensing and biological applications. This paper delivers a critical review of such inspiring biological surfaces and artificial bioinspired surfaces utilized in different applications, where material science and engineering have merged by taking inspiration from the natural systems.