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Here we report on the synthesis of highly ordered nanoporous carbon decorated with CaF2 nanoclusters along the pore wall structure using dairy milk as a carbon and calcium source through nano-hard templating approach wherein mesoporous silica SBA-15 with different pore diameters are used as template. CaF2 is introduced during the removal process of silica template and can help to enhance the charge transfer. Nitrogen adsorption results reveal that the prepared materials exhibit high specific surface area with bimodal porous structures which act as a media for the rapid ion transports through the regular and interconnected micro- and mesoporous structure. The mesoporous carbon samples also exhibit hexagonally ordered pores with rod shaped morphology, which is similar to that of the template, confirming that the templating process is successful. Finally, the optimised electrode is highly stable and offers the capacitance of 182 F g−1 at 0.5 A g−1 with almost 100% retention rate even after 5000 cycles due to a strong intimate coupling generated by the CaF2 nanoclusters within the wall structure. The electrode performance of milk derived carbon samples is much better than that of activated carbon, multiwalled carbon nanotubes and the mesoporous carbons without CaF2.

Spatial-diurnal variability in the snow/glacier melt isotope signature and their influence on hydrograph separation based on mixing model received less attention. We present isotope data from a high elevation catchment (glacierized area: 286 km2) in the central Himalaya (India) and investigated the spatial-diurnal variability of snow/glacier meltwater along with inferences of groundwater dynamics. Isotope signature variation in streamflow was small during the study period. We applied a two-component mixing model using oxygen-18 and electrical conductivity. Hydrograph separation (snow/glacier meltwater and groundwater) was carried out for Bhagirathi River at three sites i.e., Gaumukh, Bhojbasa, and Gangotri, during the ablation period of 2014 (September). The Bhagirathi River is a major tributary of river Ganga, originate from Gangotri Glacier (~30 km), the largest glacier in central Himalaya. The electrical conductivity of the river is measured in-situ and varies from 10 μS/cm to 100 μS/cm. The river water isotope signature of oxygen was ranged from −15.53‰ to −14.32‰ from Gaumukh to Gangotri, snow samples were ranged from - 17.63‰ to - 15.86‰ collected at Gaumukh. Groundwater samples were varied from −8.53‰ to-7.57‰ from Gaumukh to Gangotri. River water signature is close to snow/glacier melt runoff signature, reveal that the snow/glacier melt runoff contribution is higher in river flow. Average fractions of snow/glacier melt runoff were estimated ~82% to~76%, whereas groundwater was estimated ~18% to ~24%. The results of this study reveal the necessity of a multiple sampling approaches to characterize the snow/glacier melt and the importance of groundwater dynamics in catchments with snow/glacial runoff regime.

Around 29% of the world population does not have ready access to safe drinking water. Water contamination is a compelling issue, which needs to be addressed on a priority basis using novel technolo...

This work reports a facile, eco-friendly, and cost-effective mass-scale synthesis of metal-doped graphene sheets (MDGs) using agriculture waste of Quercus ilex leaves for supercapacitor applications. A single step-degradation catalyst-based pyrolysis route was used for the manufacture of MDGs. Obtained MDGs were further evaluated via advanced spectroscopy and microscopic techniques including Raman spectroscopy, FT-IR, XRD, SEM/EDX, and TEM imaging. The Raman spectrum showed D and G bands at 1300 cm−1 and 1590 cm−1, respectively, followed by a 2D band at 2770 cm−1, which confirmed the synthesis of few-layered MDGs. The SEM/EDX data confirmed the presence of 6.15%, 3.17%, and 2.36% of potassium, calcium and magnesium in the obtained MDGs, respectively. Additionally, the FT-IR, XRD, TEM, and SEM data including the plot profile diagrams confirmed the synthesis of MDGs. Further, a computational study was performed for the structural validation of MDGs using Gaussian 09. The density functional theory (DFT) results showed a chemisorption/decoration pattern of doping for metal ions on the few-layered graphene nanosheets, rather than a substitutional pattern. Further, resulting MDGs were used as an active material for the fabrication of a supercapacitor electrode using the polymer gel of PVA–H3PO4 as the electrolyte. The fabricated device showed a decent specific capacitance of 18.2 F g−1 at a scan rate of 5 mV s−1 with a power density of 1000 W kg−1 at 5 A g−1.

In this research, a layerwise based finite element model is presented to obtain the transient responses for functionally graded material sandwich (FGM-SW) plates under blast load. A first-order displacement field based layerwise theory with C0 continuity at layer interface has been used for the present analyses. The governing equations for the same are solved using Hamilton’s Principle in conjunction with Newmark beta average acceleration method to obtain blast response of FGM sandwich plates. The lower and upper facesheets are made of pure metal and pure ceramic, respectively and the material properties of the core is distributed from bottom to top from pure metal to pure ceramic by employing the rule of mixture. Three different cases of blast loading comprising of air-blast, step and sine are considered for the present analysis. The effect of various blast loads and power-law index is investigated on the transient behavior of functionally graded material sandwich plates.

Universal solid waste management and its hazardous effects on the ecology, ecosystem, and the global human health index are some of the major issues that are currently threatening our future. The overproduction of solid waste materials is mainly the consequence of human population explosion and extraordinary increase in global economy along with global productivity. Due to the rapid growth in global population and the related demands, the production of solid waste materials is increasing day by day. In order to have a better solution to solid waste management, the best ethical way is to convert solid waste materials into valuable carbon-based nanomaterials (CNMs) such as CNT, graphene, and carbon quantum dots (CQDs), which can further work as precursors in energy storage devices. This critical review summarizes the recent progress in the structural forms and current situational analysis of universal solid waste based CNMs. It also includes broadly discussed issues, starting with the current waste situation analysis of global energy crisis and the production of graphene, including its counterparts, as the precursors for supercapacitor applications. A paradigm study of various solid waste derived CNMs with their significance, which, in particular, depends upon the types of CNMs and the classification of solid waste derived CNMs on the basis of different types of pore size and pore distribution, has been carried out. The various structural modifications and their effects on the electrochemical properties have been discussed thoroughly for supercapacitor applications including their future possibilities and scope. The review outlines the crucial mechanism followed during the charge storage of different kinds of supercapacitors and various electrochemical calculations involved during the performance testing of the fabricated device. We hope that the target audience, belonging to the energy or material science field, may acquire relevant information from this review, which may further help them to design futuristic studies in the field.

Given the non-biodegradable nature of plastic, its recycling and upcycling are critical to ensure effective waste management and resource conservation, with a cradle-to-cradle approach. Herewith, w...

Bio-based composites are getting popular due to its major contribution to the green materials industry application. Green techniques reduce the toxic gas emission, waste generation and improve envi...

The experimental realization and computational validation for graphene oxide (GO) supported palladium (Pd)-iron (Fe) nanohybrids as a new generation electrocatalyst for proton-exchange membrane fuel cells (PEMFCs) has been reported. The experimental apprehension of the present catalyst system has been initiated with the graphene oxide, followed by the doping of Pd and Fe via thermal inter calation of palladium chloride and iron chloride with the in-situ downstream reduction to get nanohybrids of the GO-Pd-Fe. These nanohybrids are subsequently characterized by RAMAN, FT-IR, UV–Vis, XRD, SEM, EDS, TEM and HRTEM analysis. Furthermore, the first principle calculations based on Density Functional Theory (DFT) with semi-empirical Grimme DFT-D2 correction has been performed to support the experimental findings. Computational results revealed the alteration of graphene electronic nature from zero-band gaped to metallic/semi-metallic on adsorption of transition metal clusters. Moreover, the defect sites of the graphene surface are more favorable than the pristine sites for transition metal adsorption owing to the strong binding energies of the former. Electrochemical studies show that GO-Pd-Fe nanohybrids catalyst (Pd: Fe = 2:1) demonstrates excellent catalytic activity as well as the higher electrochemical surface area of (58.08 m2/g Pd–Fe)−1 which is higher than the commercially available Pt/C catalyst with electrochemical surface area 37.87 m2/(g Pt)−1.

An alarming increase in bacterial resistance towards various types of antibiotics makes it imperative to design alternate or combinational therapies to treat stubborn bacterial infections. In this perspective, emerging tools like nanozymes, nanomaterials with biological enzyme like characteristics, are being utilised to control infections caused by bacterial pathogens. Among several nanozymes used for antibacterial applications, Fe3O4 nanoparticles (NP) received great attention due to their effective peroxidase like activity. The pH dependent peroxidase activity of Fe3O4 NP results in generation of OH radical via the unique Fenton chemistry of iron. However, their pH dependent activity is restricted to acidic environment and dramatic loss in antibacterial activity is observed at near neutral pH. Here we describe a novel strategy to overcome the pH lacunae of citrate coated Fe3O4 NP by utilizing adenosine triphosphate disodium salt (ATP) as a synergistic agent to accelerate the OH radical production and restore its antibacterial activity over a wide range of pH. This synergistic combination (30 µg/mL Fe3O4 NP and 2.5 mM ATP) shows a high bactericidal activity against both gram positive (B. subtilis) and gram negative (E. coli) bacterial strains, in presence of H2O2, at neutral pH. The synergistic effect (Fe3O4 NP + ATP) is determined from the viability assessment and membrane damage studies and is further confirmed by comparing the concentration of generated OH radicals. Over all, this study illustrates ATP assisted and OH-mediated bactericidal activity of Fe3O4 nanozyme at near neutral pH.

The demand for energy and energy storage devices is the urgent need of our society due to heavy dependence on electric appliances. Hence, the demand of graphene-like smart materials has grown tremendously in the past years. Herein, we investigated the binder-free graphene allies named reduced graphene oxide (rGO) as electrode materials for the supercapacitor after the reduction of graphene oxide by sinking and leaving process. The rGO-based devices show the areal specific capacitance of 80.2 and 7.89 mF cm−2 with aqueous 1M phosphoric acid (H3PO4) and poly (vinyl alcohol)-H3PO4 polymer gel electrolytes, respectively, over the graphite sheet.

Nanoporous carbon (HNC) with a flake and nanotubular morphology and a high specific surface area is prepared by using natural halloysite nanotubes (HNTs), a low-cost and naturally available clay material with a mixture of flaky and tubular morphology. A controlled pore-filling technique is used to selectively control the porosity, morphology, and the specific surface area of the HNC. Activated nanoporous carbon (AHNC) with a high specific surface area is also prepared by using HNT together with the activation process with zinc chloride (ZnCl2). HNC exhibits flakes and tubular morphologies, which offer a high specific surface area (837 m2/g). The specific surface area of AHNC is 1646 m2/g, 74 times greater than the specific surface area of pure HNT (22.5 m2/g). These data revealed that the single-step activation combined with the nanotemplating results in creating a huge impact on the specific surface area of the HNC. Both HNC and AHNC are employed as adsorbents for CO2 adsorption at different pressures and adsorption temperatures. The CO2 adsorption capacity of AHNC is 25.7 mmol/g at 0 °C, which is found to be significantly higher than that of activated carbon (AC), mesoporous carbon (CMK-3), mesoporous carbon nitride (MCN-1), and multiwalled carbon nanotube (MWCNT). AHNC is also tested as an electroactive material and demonstrates good supercapacitance, cyclic stability, and high capacitance retention. Specific capacitance of AHNC in the aqueous electrolyte is 197 F/g at 0.3 A/g, which is higher than that of AC, MWCNT, and CMK-3. The technique adopted for the preparation of both HNC and AHNC is quite unique and simple, has the potential to replace the existing highly expensive and sophisticated mesoporous silica-based nanotemplating strategy, and could also be applied for the fabrication of series of advanced nanostructures with unique functionalities.

Biochar is produced as a charred material with high surface area and abundant functional groups by pyrolysis, which refers to the process of thermochemical decomposition of organic material at elevated temperatures in the absence of oxygen. The carbon component in biochar is relatively stable, and, hence, biochar was originally proposed as a soil amendment to store carbon in the soil. Biochar has multifunctional values that include the use of it for the following purposes: soil amendment to improve soil health, nutrient and microbial carrier, immobilising agent for remediation of toxic metals and organic contaminants in soil and water, catalyst for industrial applications, porous material for mitigating greenhouse gas emissions and odorous compounds, and feed supplement to improve animal health and nutrient intake efficiency and, thus, productivity. This article provides for the first time an overview of the multifunctional values and unintended consequences of biochar applications. Refereed/Peer-reviewed

Research on cerium oxide nanoparticles (nanoceria) has captivated the scientific community due to their unique physical and chemical properties, such as redox activity and oxygen buffering capacity, which made them available for many technical applications, including biomedical applications. The redox mimetic antioxidant properties of nanoceria have been effective in the treatment of many diseases caused by reactive oxygen species (ROS) and reactive nitrogen species. The mechanism of ROS scavenging activity of nanoceria is still elusive, and its redox activity is controversial due to mixed reports in the literature showing pro-oxidant and antioxidant activity. In lieu of its current research interest, it is critical to understand the behaviour of nanoceria in the biological environment and provide answers to some of the critical and open issues. This review critically analyses the status of research on the application of nanoceria to treat diseases caused by ROS. It reviews the proposed mechanism of action and shows the effect of surface coatings on its redox activity. It also discusses some of the crucial issues in deciphering the mechanism and redox activity of nanoceria and suggests areas of future research., 43 pages; 6 figures; 3 tables

This research presents a nonlinear transient analysis of porous functionally graded material (FGM) plates subjected to a step blast loading using the finite element method approach. A C0 formulation has been established by implementing a first-order displacement field with an eight-noded isoparametric element. The governing differential equations have been derived using total lagrangian formulation. Subsequently, Newmark-Beta scheme along with the modified Newton-Raphson iterative method has been employed to obtain the solution of the resultant governing differential equation. The results obtained from the present FEM model are compared with the benchmark solutions from the available literature. The effect of parameters such as power index, porosity parameter and side-to-thickness ratio on the transient response of FGM plate is investigated under step blast load.

In this work, free vibration behaviour of sinusoidally corrugated functionally graded composite panel is examined. In this analysis, the functionally graded panel is comprised of metal at the bottom surface and ceramic at the top surface, and metal/ceramic phase between the top and bottom surfaces of the panel. The effective material properties of in-homogenous functionally graded material are obtained using simple rule-of-mixture, whereas the volume fractions of each material constituents are computed through the power-law distribution. The corrugated panel is modelled and analysed via finite element tool (ANSYS APDL) using eight-noded shell element (SHELL281). The displacement field is expressed using first-order shear deformation theory with six degrees-of-freedom. The Block-Lanczos method is employed to obtain the free vibration responses of the corrugated panel. The accuracy of the present model is exhibited through the comparison study in which the present results are compared with the previously reported results. In addition, numerous examples are illustrated to demonstrate the influences of various geometrical and material parameters, such as side-to-thickness ratio, corrugation, aspect ratio and power-law index, and support conditions on the free vibration behaviour of corrugated panel

This research work presents the comparison of free vibration response for functionally graded materials (FGM) sandwich shell panels having bottom and top layers made of pure metal and ceramic and the core of the same is made of FGM. The material properties of the FGM core are varied according to the power-law model (P-FGM) and the sigmoid model (S-FGM). A finite element model (FEM) based on the displacement field according to first-order shear deformation theory for each layer has been used to develop the governing differential equation for free vibration analysis of P-FGM sandwich and S-FGM sandwich shell panels. The accuracy of the present finite element model has been demonstrated by comparing results with benchmark examples from with those published in literature. Next, the free vibration responses obtained from two different material modeling Viz., power-law variation and Sigmoid variation for FGM core of FGM sandwich shell have been compared by varying parameters like volume fraction index, curvature, and geometrical boundary conditions.

The presence of an excessive concentration of CO2 in the atmosphere needs to be curbed with suitable measures including the reduction of CO2 emissions at stationary point sources such as power plants through carbon capture technologies and subsequent conversion of the captured CO2 into non-polluting clean fuels/chemicals using photo and/or electrocatalytic pathways. Porous materials have attracted much attention for carbon capture and in the recent past; they have witnessed significant advancements in their design and implementation for CO2 capture and conversion. In this context, the emerging trends in major porous adsorbents such as MOFs, zeolites, POPs, porous carbons, and mesoporous materials for CO2 capture and conversion are discussed. Their surface texture and chemistry, and the influence of various other features on their efficiency, selectivity, and recyclability for CO2 capture and conversion are explained and compared thoroughly. The scientific and technical advances on the material structure versus CO2 capture and conversion provide deep insights into designing effective porous materials. The review concludes with a summary, which compiles the key challenges in the field, current trends and critical challenges in the development of porous materials, and future research directions combined with possible solutions for realising the deployment of porous materials in CO2 capture and conversion.

Evaluating the colloidal stability and enzyme mimetic nature of nanozymes at different buffer conditions is necessary to develop novel biosensing, biomedical and environmental applications. It is established that Fe3O4 nanoparticles show optimum peroxidase activity at pH 4 and it has also been shown that nucleotides like ATP can exhibit synergistic effect to enhance peroxidase activity at neutral pH. In this study we show the effect of buffers, pH and presence of ATP on peroxidase activity of Fe3O4 NPs and elucidate the mechanism involved in enhanced activity at neutral pH. Fe3O4 NPs colloidal stability was assessed over a period of 72 h from acidic to neutral pH. It was explained that ˙OH radical generation from the synergistic combination of nucleotides and Fe3O4 NPs resulted in peroxidase activity at neutral pH and found that buffer concentration has a major effect on this activity. These findings challenge the existing theory of peroxidase activity demonstrated by Fe3O4 NPs at acidic pH. Moreover, the posibility can overcome the pH lacuna in designing novel biosensors and can also extend the heterogeneous Fenton reaction of Fe3O4 NPs over a wide range of pH.

Background: Biomedical applications of Magnetic Nanoparticles (MNPs) are creating a major impact on disease diagnosis and nanomedicine or a combined platform called theranostics. A significant progress has been made to engineer novel and hybrid MNPs for their multifunctional modalities such as imaging, biosensors, chemotherapeutic or photothermal and antimicrobial agents. MNPs are successfully applied in biomedical applications due to their unique and tunable properties such as superparamagnetism, stability, and biocompatibility. Approval of ferumoxytol (feraheme) for MRI and the fact that several Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are currently undergoing clinical trials have paved a path for future MNPs formulations. Intensive research is being carried out in designing and developing novel nanohybrids for multiple applications in nanomedicine. Objective: The objective of the present review is to summarize recent developments of MNPs in imaging modalities like MRI, CT, PET and PA, biosensors and nanomedicine including their role in targeting and drug delivery. Relevant theory and examples of the use of MNPs in these applications have been cited and discussed to create a thorough understanding of the developments in this field. Conclusion: MNPs have found widespread use as contrast agents in imaging modalities, as tools for bio-sensing, and as therapeutic and theranostics agents. Multiple formulations of MNPs are in clinical testing and may be accepted in clinical settings in near future.

Climate change effects on Himalayas are expectedly more pronounced than any other mountainous ecoregion of the world with expected threat of meltdown by the year 2100 if effective checks are not imposed. The impacts of this climate warming in the geologically fragile Himalayas has started to show its effects on shifting precipitation patterns, increasing temperatures, glaciers meltdown, species richness patterns and overall unpredictable microclimatic conditions. For measuring such impacts of current climate warming in Himalayan ecosystems, need of ecological substitutes has been stressed on by different United Nation conventions. Lichens in contrast to vascular flora have long been proved to act as cost effective global indicators for measuring ecosystems responses to environmental climate. The variations in microclimatic attributes and their effects on photosynthetic efficiency and distribution were studied in geologically fragile ecosystem of Govind Pashu Vihar National Park in Garhwal Himalayas. Total 217 species of lichens comprising 80 genera and 35 families were found along different elevations. Among the different habitat groups, corticolous lichens showed their dominance (123 species) followed by saxicolous (65 species) and terricolous (29 species) lichens. Corticolous forms were dominated by crustose while saxicolous and terricolous were mostly fruticose growth forms. Mostly large number of species showed a narrow distribution with maximum species richness observed in mid elevation zones (1950–2200 m) followed by a gradual decline towards higher elevations. Phaeophyscia hispidula, Parmotrema reticulatum and Flavoparmelia caperata showed wider ecological amplitude. Out of these species, P. hispidula and F. caperata were further subjected to chlorophyll fluorescence measurements with a pulse amplified modulated fluorometer to access photosynthetic quenching efficiencies. Maximum electron transport rates (ETR; 96 ± 5.76 μmol e− m−2 s−1) were observed in Phaeophyscia hispidula (1550 m) while F. caperata showed nearly 21% lower ETR. Photochemical quenching (qP; 0.5 ± 0.01) was maximum at 1550 m elevation in F. caperata while P. hispidula showed maximum qP values at 2200 m elevation, showing it’s higher tolerances towards extreme light stresses. F. caperata showed higher (0.102 ± 0.003) non photochemical quenching (NPQ) in comparison to P. hispidula (0.062 ± 0.001) at extreme elevations of 3508 m. P. hispidula overall showed more toxitolerant nature towards abiotic stresses as compared to F. caperata. Higher photosynthetically active radiation (PAR; 1600–2350 µmol m−2 s−1), thallus hydration levels and extreme variations in air temperature (5.75–31.65 °C), ambient humidity along elevations were imperative in controlling species richness, distribution and photosynthetic quenching of lichen flora in the region.

Waste plastic management and converting it into value added products is one of the greatest challenges before the scientific community. The present work reports a cost effective, environment friendly and mass production capable method for upcycling of solid plastic waste into value added product (graphene). A two step pyrolysis processes i.e. firstly at 400 °C in presence of nanoclay followed by at 750 °C under nitrogen atmosphere was performed to obtain a black charged residue. Raman spectroscopy was performed on the obtained residue, where the observed D and G bands at 1342 cm−1 and 1594 cm−1, respectively, confirm the synthesis of graphene nano sheets. In addition, a broad 2D band at 2790 cm−1 confirm the presence of few layer graphene nano sheets. The obtained graphene nanosheets were also confirmed through the computational data by Gaussian09, where the peaks at 1379 cm−1 and 1596 cm−1 for D and G band, respectively, make a good agreement with experimental data. TEM, FT-IR and EDX spectroscopy were also performed to confirm the synthesis of graphene nanosheets including the functional group identification and quantitative analysis for elements, respectively.

Cerium oxide Nanoparticles (CNPs) are of significant interest to the scientific community due to their wide spread applications in a variety of fields. It is proposed that size dependent variations in the extent of Ce3+ and Ce4+ oxidation states of cerium in CNPs determines the performance of CNPs in application environments. To obtain greater molecular and structural understanding of chemical state transformations previously reported for ceria ≈ 3 nm nanoparticles (CNPs) in response to changing ambient conditions, microXRD and Raman measurements were carried out for various solution conditions. The particles were observed to undergo a reversible transformation from a defective ceria structure to a non-ceria amorphous oxy-hydroxide/peroxide phase in response to the addition of 30% hydrogen peroxide. For CNPs made up of ~8 nm crystallites, a partial transformation was observed and no transformation was observed for CNPs made up of ~ 40 nm crystallites. This observation of differences in size dependent transition behavior may help explain the benefits of using smaller CNPs in applications requiring regenerative behavior.

Herein, we report the first time application of waste plastic derived 3D graphene nanosheets (GNs) for hole transport material (HTM) free perovskite solar cells (PSCs), where 3D GNs have been employed as an electrode dopant material in monolithic carbon electrode based mesoscopic PSCs. Waste plastics were upcycled into high-quality 3D GNs by using two-step pyrolysis processes, where, a nickel (99.99%) metal mesh was taken as the catalytic and degradation template to get an acid free route for the synthesis of 3D GNs. Raman spectroscopy, HRTEM analysis and XRD analysis show the presence of 1–2 graphene layers within the 3D GNs. Further, the optical band gap study has also been performed to analyze the applicability of 3D GNs for PSCs. The optimized device with 3D GNs shows a power conversion efficiency (PCE) of 12.40%, whereas the carbon-based control device shows a PCE of 11.04%. Further, all other device parameters such as short circuit current (Jsc), open circuit voltage (Voc) and fill factor (FF) have been improved with the addition of 3D GNs. The performance enhancement in 3D GN doped HTM free PSC solar cells is attributed to the enhancement in conductivity and reduced recombination within the device. Further, the photocurrent study shows that the 3D GN device shows better performance as compared to the reference device due to the larger diffusion current. Thus, the upcycling of waste plastics into 3D GNs and their exploitation for application in energy conversion show an effective and potential way to convert waste into energy.

Cerium oxide nanoparticles have been shown to mimic oxidoreductase enzymes by catalyzing the decomposition of organic substrates and reactive oxygen species. This mimicry can be found in superoxide radicals and hydrogen peroxides, harmful molecules produced in oxidative stress asso-ciated diseases. Despite the fact that nanoparticle functionalization is mandatory in the context of nanomedicine, the influence of polymer coatings on their enzyme-like catalytic activity is poorly understood. In this work, six polymer coated cerium oxide nanoparticles are prepared by associa-tion of 7.8 nm cerium oxide cores with two poly(sodium acrylate) and four poly(ethylene glycol) (PEG) grafted copolymers with different terminal or anchoring end groups, such as phosphonic acids. The superoxide dismutase-, catalase-, peroxidase- and oxidase-like catalytic activities of the coated nanoparticles were systematically studied. It is shown that the polymer coatings do not af-fect the superoxide dismutase-like, impair the catalase-like and oxidase-like and surprisingly im-proves peroxidase-like catalytic activities of cerium oxide nanoparticles. It is also demonstrated that the particles coated with the PEG-grafted copolymers perform better than the poly(acrylic acid) coated ones as oxidoreductase-like enzymes, a result that confirms the benefit of having phosphon-ic acids as anchoring groups at the particle surface., Comment: 23 pages, 8 figures, 3 tables

This paper presents the bending analysis of sandwich shell panels having exponentially graded core with top and bottom facesheets which are composed of pure ceramic and pure metal respectively. The layerwise finite element formulation is developed by using a displacement field according to first-order shear deformation theory for each layer that maintains continuity at the layer interface. The governing differential equation for the present problem is obtained using the principle of minimum total potential energy. The correctness of the presented finite element formulation is established by validating the results obtained with the benchmark. Next, the bending responses for exponentially graded sandwich shell panels (E-FGM-SW) are obtained. The effect of parameters like curvature ratio and material properties on the bending responses of exponentially graded sandwich shell panels is investigated. It has been shown here that present layerwise finite element formulation is simple, accurate and widely applicable.

We report the temperature and pH responsive dispersion of multi-walled carbon nanotubes (MWNTs) in poly(N-isopropylacrylamide) (PNIPAM) and poly- l -lysine hydrobromide (PLL) based polymeric matrix. An excellent dispersion of MWNTs in PNIPAM was observed below its lower critical solution temperature (LCST; 32 °C), however, aggregation of MWNTs observed above this critical temperature. The pH effect on MWNTs dispersion was also analysed, where at room temperature PLL/PNIPAM mixture demonstrates an excellent dispersion of MWNTs at pH 7 and 10, whereas, an agglomeration was observed at pH 4. PLL transforms from ionized coil to α-helix conformation with increase in pH (more globular shape), thus the solution demonstrates agglomeration of MWNT at low pH and well dispersed MWNTs at high pH. Density functional theory based analysis was also carried out to concurrent changes in the interfacial morphology, where PNIPAM shows better interaction with CNT than PLL including a higher strength of interaction. This can be attributed to the geometry curvature of PNIPAM that enables strong van der Waals interaction with the CNT surface, thus, PNIPAM may serve as a better dispersion agent than PLL. The quick responsive nature of PNIPAM and PLL shows notable changes with variation in temperature and pH, thus may be helpful to fabricate CNT based smart devices.

The international ISO Standard 20579‐4, dealing with the history and preparation of nano‐objects for surface analysis, has been developed to help address some of the replication and reproducibility issues caused by the fundamental nature of nanoobjects. Although all types of samples requiring surface analysis need thoughtful preparation, nano‐objects, for which many properties are controlled by their surfaces, present additional challenges in order to avoid variations and artefacts due to the handling and preparation of materials prior to analysis. This international standard is part of a series of standards related to preparation of samples for surface chemical analysis. Parts 1 and 2 of ISO Standard series 20579 address general issues that apply to many samples. Part 3, which is still in development, will focus on biomaterials. Part 4 specifically considers issues that arise due to the inherent nature of nano‐objects. Because of sensitivity to their environment, the standard indicates the minimum Information that needs to be reported about the handling and preparation of nano‐objects prior to surface analysis. This information should become part of sample provenance information that helps assure the reliability and usefulness of data obtained from surface‐analysis in the context of the synthesis, processing, and analysis history of a batch of material. Application of this standard can help address reproducibility and traceability issues associated with synthesis, processing, and characterization of nano‐objects in research and commercial applications.

In this work, the analytical and experimental study on isolation of microfibers from Hibiscus sabdariffa var. altissima fiber using the steam explosion technique is discussed. Structural an...

Catalytically active individual gold (Au) and cerium oxide (CeO2) nanoparticles (NPs) are well known to exhibit specific enzyme-like activities, such as natural catalase, oxidase, superoxide dismutase, and peroxidase enzymes. These activities have been maneuvered to design several biological applications such as immunoassays, glucose detection, radiation and free radical protection and tissue engineering. In biological systems, multienzyme complexes are involved in catalyzing important reactions of essential metabolic processes such as respiration, biomolecule synthesis, and photosynthesis. It is well known that metabolic processes linked with multienzyme complexes offer several advantages over reactions catalyzed by individual enzymes. A functional nanozyme depicting multienzyme like properties has eluded the researchers in the nanoscience community for the past few decades. In the current report, we have designed a functional multienzyme in the form of Gold (core)-CeO2 (shell) nanoparticles (Au/CeO2 CSNPs) exhibiting excellent peroxidase, catalase, and superoxide dismutase enzyme-like activities that are controlled simply by tuning the pH. The reaction kinetic parameters reveal that the peroxidase-like activity of this core-shell nanozyme is comparable to natural horseradish peroxidase (HRP) enzyme. Unlike peroxidase-like activity exhibited by other nanomaterials, Au/CeO2 CSNPs showed a decrease in hydroxyl radical formation, suggesting that the biocatalytic reactions are performed by efficient electron transfers. A significant enzyme-like activity of this core-shell nanoparticle was conserved at extreme pH (2–11) and temperatures (up to 90 °C), clearly suggesting the superiority over natural enzymes. Further, the utility of peroxidase-like activity of this core-shell nanoparticles was extended for the detection of glucose, which showed a linear range of detection between (100 µM to 1 mM). It is hypothesized that the proximity of the redox potentials of Au+/Au and Ce (III)/Ce (IV) may result in a redox couple promoting the multienzyme activity of core-shell nanoparticles. Au/CeO2 CSNPs may open new directions for development of single platform sensors in multiple biosensing applications.

Ligand-functionalized nanoparticles have replaced bare nanoparticles from most biological applications. These applications require tight control over size and stability of nanoparticles in aqueous medium. Understanding the mechanism of interaction of nanoparticle surfaces with functional groups of different organic ligands such as carboxylic acids is confounding despite the two decades of research on nanoparticles because of the inability to characterize their surfaces in their immediate environment. Often the surface interaction is understood by correlating the information available, in a piecemeal approach, from surface sensitive spectroscopic information on ligands and the bulk and surface information on nanoparticles. In present study we report the direct interaction of 5–7 nm cerium oxide nanoparticles surface with acetic acid. An in-situ XPS study was carried out by freezing the aqueous solution of nanoparticles to liquid nitrogen temperatures. Analysis of data collected concurrently from the ligand...

Nanoceria is considered as a potent antioxidant (free radical scavenger) and its enzymatic activity is reported to be a function of the oxidation state of surface cerium ions. Here we demonstrate phosphine ligand-dependent enzymatic activity of nanoceria irrespective of its as-synthesized oxidation state.

Specific reactivity of cerium oxide nanoparticles with phosphate ions was used to design a novel antibacterial system. The redox sensitivity of cerium oxide nanoparticles (CeNPs) was used to irreversibly scavenge phosphate ions from the microbial growth media resulting in nutrient starvation in microbes. Cerium oxide nanoparticles surface was engineered with different ratios of ( $$\hbox {Ce}\,{(+3)}/\hbox {Ce}\,{(+4)})$$ cerium oxidation states and the effect of surface oxidation states was evaluated on the antibacterial activity. The nutrient depletion-based antibacterial activity is demonstrated selectively by CeNPs with higher $$\hbox {Ce}\,{(+3)}/\hbox {Ce}\,{(+4)}$$ ratio on the surface. The surface chemistry of $$\hbox {Ce}\,{(+3)}$$ is altered in the presence of phosphate, resulting in the irreversible formation of surface cerium phosphates leading to the loss of its intrinsic superoxide dismutase (SOD) activity. It is hypothesized that nutrient starvation by $$\hbox {Ce}\,{(+3)}$$ leads to oxidative stress in microbes which is not neutralized by the altered surface chemistry of CeNPs with high $$(\hbox {Ce}\,{(+3)}/\hbox {Ce}\,{(+4)})$$ ratio. On the contrary, CeNPs with higher $$(\hbox {Ce}\,{(+4)}/\hbox {Ce}\,{(+3)})$$ ratio did not show any reactivity towards phosphate, thus depicted no antibacterial activity, confirming the hypothesis that surface chemistry, rather than size or morphology-dependent toxicity is the main reason for the observed antibacterial activity of CeNPs.

Fe3O4 nanoparticles (Fe3O4 NPs), demonstrating peroxidase-like activity has garnered attention in the detection of several biomolecules, therefore, emerged as an excellent nano-biosensing agent. The intrinsic peroxidase-like activity of Fe3O4 NPs at acidic pH is the fundamental action driving the oxidation of substrates like TMB, resulting in a colorimetric product formation used in the detection of biomolecules. Hence, the detection sensitivity essentially depends on the ability of oxidation by Fe3O4 NPs in presence of H2O2. However, the limited sensitivity and pH condition constraint have been identified as the major drawbacks in the detection of biomolecules at physiological pH. Herein, we report overwhelming of the fundamental limitation of acidic pH and tuning the peroxidase-like activity of Fe3O4 NPs at physiological pH by using ATP. In presence of ATP, Fe3O4 NPs exhibited enhanced peroxidase-like activity over a wide range of pH and temperatures. Mechanistically, it was found that the ability of ATP to participate in single electron transfer reaction, through complexation with Fe3O4 NPs, results in the generation of hydroxyl radicals which are responsible for enhanced peroxidase activity at physiological pH. We utilized this ATP-mediated enhanced peroxidase-like activity of Fe3O4 NPs for single step detection of glucose with a colorimetric detection limit of 50μM. Further, we extended this single step detection method to monitor glucose level in human blood serum and detected in a time span of

2D carbon nanomaterials such as graphene and its oxide counterpart have sought good research attention for their application as well as fundamental interest. Especially the versatility of graphene oxide establishes its elite candidature in every field because of diverse application potential. Here we are reporting a greener, eco-friendly and cost effective one step hydrothermal route for the synthesis of potassium doped graphene oxide (K-doped GO) from agricultural waste i.e. Quercus ilex Fruit. The elemental analysis and XPS study showed the high percentage (6.81%) of natural doping of potassium. The K-doped GO is specific and demonstrates bright blue photoluminescence (PL) under UV-light (λex = 365 nm). Low toxicity, intracellular localization, good biocompatibility and strong PL properties of the synthesized K-doped GOs portray it as an excellent bio-imaging agent holding great promise in analytical and biological fields.

We report on the preparation of highly efficient nanoporous activated biocarbons (NABs) from alligator weed with high surface areas, pore volumes, tunable microporosity and oxygen functional groups for carbon dioxide adsorption. Alligator weed is converted into a non-porous carbon at 600 °C, which is then activated using potassium hydroxide at 800 °C through liquid state chemical activation. The simple synthesis provides easy control over experimental conditions which are carefully manipulated to yield the optimized material with a high specific surface area (3106 m2 g−1) and a high pore volume (1.62 cm3 g−1). It is also demonstrated that the microporosity and surface oxygen functional groups can be controlled with a simple adjustment of the amount of potassium hydroxide. Owing to the excellent textural features, the optimized material adsorbed a high amount of carbon dioxide at 0 °C (30.4 mmol g−1), 10 °C (27.7 mmol g−1) and 25 °C (23.3 mmol g−1) at a high pressure of 30 bar, which is much higher than that of activated carbon, ordered nanoporous carbon and mesoporous silicas. It also shows a low value of isosteric heat of adsorption (~22 kJ mol−1) that indicates physical adsorption. The material with high microporosity shows impressive carbon dioxide adsorption capacity of 6.4 mmol g−1 at 0 °C and low pressure of 1 bar. The high and low pressure carbon dioxide adsorption values indicate that the materials are promising adsorbents for carbon dioxide and the physical adsorption implies an easier regeneration. These findings suggest that biomass alligator weed can be utilized for devising advanced nanomaterials with high porosity for carbon capture.

Two enhanced temperature-index (T-index) models are proposed by incorporating meteorological parameters viz. relative humidity, wind speed and net radiation. The models are an attempt to explore different climatic variables other than temperature affecting glacier surface melting. Weather data were recorded at Chorabari Glacier using an automatic weather station during the summers of 2010 (July 10 to September 10) and 2012 (June 10 to October 25). The modelled surface melt is validated against the measured point surface melting at the snout. Performance of the developed models is evaluated by comparing with basic temperature-index model and is quantified through different efficiency criteria. The results suggest that proposed models yield considerable improvement in surface melt simulation. Consequently, the study reveals that glacier surface melt depends not only on temperature but also on weather parameters viz. relative humidity, wind speed and net radiation play a significant role in glacier surface melting. This approach provides a major improvement on basic temperature-index method and offers an alternative to energy balance model.

In this report, we demonstrate on the preparation of mesoporous graphitic carbon nitride (gCN) with 3D porous structure using dicyandiamide as a CN precursor and KIT-6 as a template via hard-template replication method and its superior photocatalytic hydrogen evolution activity under simulated sunlight. The powder X-ray diffraction, nitrogen adsorption and near edge X-ray absorption fine structure (NEXAFS) results reveal that the prepared materials possess gCN crystal structure with ordered mesopores and a 3D porous structure and a high specific surface area (221 m2/g). UV–Vis and PL spectra show that the absorption edges of mesoporous gCNs are slightly blue-shifted and the PL intensity is remarkably suppressed. The photocatalytic hydrogen evolution activity of gCN-KIT-6 under solar simulated irradiation is 1.92 mmol·g−1 h−1 which is much higher than that of gCN with 2D mesoporous structure, gCN from silica nanoparticle and bulk nonporous gCN. This high photocatalytic activity of gCN-KIT-6 can be attributed to 3D structure and the retarded electron-hole recombination.

Carbon nanomaterials such as graphene, carbon nanotubes, and fullerenes are superior materials over the other materials in the field of nanoscience and material science, due to their potential applications in various fields of science and technology. These materials are used as nanofiller for the preparation of polymer nanocomposites and are useful to enhance their properties exceptionally. However, their problem is associated with their poor solubility in aqueous and organic solvents which restricts their compatibility with polymer matrices, stopping these materials rfom achieving their full potential. To overcome this issue, surface modification of carbon nanomaterials via covalent and noncovalent functionalization with different polymers has previously been studied. This chapter highlights the noncovalent and covalent functionalization of carbon nanomaterials (graphene and CNT) through various types of interactions between polymers and carbon nanomaterials.

The series of breakthroughs that have occurred within the realm of nanotechnology have been the source of several new products and technological interventions. One of the most salient examples in this regard is the widespread employment of titanium dioxide (TiO2) nanoparticles across a range of consumer goods. Given that waste is generated at every stage of the consumer-product cycle (from production to disposal), many items with TiO2 nanoparticles are likely to end up being discarded into water bodies. In order to understand the interaction of TiO2 NPs with aquatic ecosystem, the ecological fate and toxicity of TiO2 NPs was studied by exposing zebrafish embryos to a combination of abiotic factors (humic acid and clay) to assess its effect on the development of zebrafish embryos. The physiological changes were correlated with genetic marker analysis to holistically understand the effect on embryos development. Derjaguin–Landau–Verwey–Overbeek (DLVO) theory was used to analyze the interaction energy between TiO2 NPs and natural organic matter (NOM) for understanding the aggregation behavior of engineered nanoparticles (ENPs) in media. The study revealed that combination of HA and clay stabilized TiO2 NPs, compared to bare TiO2 and HA or clay alone. TiO2 NPs and TiO2 NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA and HA + clay showed protective effect on zebrafish embryo development. The complete system analysis demonstrated the possible ameliorating effects of abiotic factors on the ecotoxicity of ENPs.

Copper oxide nanoparticles (CuO NPs) is one of the most commonly used metal oxide nanoparticles for commercial and industrial products. An increase in the manufacturing and use of the CuO NPs based products has increased the likelihood of their release into the aquatic environment. This has attracted major attention among researchers to explore their impact in human as well as environmental systems. CuO NPs, once released into the environment interact with the biotic and abiotic constituents of the ecosystem. Hence the objective of the study was to provide a holistic understanding of the effect of abiotic factors on the stability and aggregation of CuO NPs and its correlation with their effect on the development of zebrafish embryo. It has been observed that the bioavailability of CuO NPs decrease in presence of humic acid (HA) and heteroagglomeration of CuO NPs occurs with clay minerals. CuO NPs, CuO NPs + HA and CuO NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA with clay showed protective effect on zebrafish embryo development. These findings provide new insights into the interaction of NPs with abiotic factors and combined effects of such complexes on developing zebrafish embryos genetic markers., by Krupa Kansara, Archini Paruthi, Superb K.Misra, Ajay S. Karakotia and Ashutosh Kumar

Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO2 capture and its reduction into clean and green low-carbon fuels and valuable chemical feedstock by using sustainable and intermittent renewable energy sources of sunlight and electricity through the heterogeneous photo(electro)catalysis. Here, the latest research results in this field are summarized, including implementation of novel functionalized nanostructured CNs and their hybrid heterostructures in meeting the stringent requirements to raise the efficiency of the CO2 reduction process by using state-of-the-art photocatalysis, electrocatalysis, photoelectrocatalysis, and feedstock reactions. The research in this field is primarily focused on advancement in the synthesis of nanostructured and functionalized CN-based hybrid heterostructured materials. More importantly, the recent past has seen a surge in studies focusing significantly on exploring the mechanism of their application perspectives, which include the behavior of the materials for the absorption of light, charge separation, and pathways for the transport of CO2 during the reduction process.

We studied the interactions between the carboxylate anchoring group from trimethylacetic acid (TMAA) and CeO2(111) surfaces as a function of oxygen stoichiometry using in situ X-ray photoelectron spectroscopy (XPS). The stoichiometric CeO2(111) surface was obtained by annealing the thin film under 2.0 × 10(-5) Torr of oxygen at ∼550 °C for 30 min. In order to reduce the CeO2(111) surface, the thin film was annealed under ∼5.0 × 10(-10) Torr vacuum conditions at 550 °C, 650 °C, 750 °C and 850 °C for 30 min to progressively increase the oxygen defect concentration on the surface. The saturated TMAA coverage on the CeO2(111) surface determined from XPS elemental composition is found to increase with increasing oxygen defect concentration. This is attributed to the increase of under-coordinated cerium sites on the surface with the increase in the oxygen defect concentrations. XPS results were in agreement with periodic density functional theory (DFT) calculations and indicate a stronger binding between the carboxylate group from TMAA and the oxygen deficient CeO2-δ(111) surface through dissociative adsorption.

In the present study, we have developed empirical relationships to estimate meteorological parameters at the glacier altitude from the data on non-glacier altitude. Meteorological data collected from automatic weather station at Chorabari Glacier from November 2011 to May 2013 are analysed and empirical equations for air temperature, relative humidity and incoming global radiation are proposed. The dataset of one year (November 2011-October 2012) is used in the calibration of models, while data for the next seven months (November 2012-May 2013) are employed to validate the models. Moreover, an analytical study is also conducted on incoming diffuse radiation (estimated through the established model for India). Further, a relationship is established to correlate the diffuse component of two sites. Variation trend of meteorological parameters with altitude is found to be different for each of the parameters, viz. quadratic for air temperature, logarithmic for relative humidity, and linear for global and diffuse radiation. Performance of the generated equations is tested through various statistical methods. The study reveals that developed correlations are able to give a good match with in situ measurements.

Cerium oxide nanoparticles have found numerous applications in the biomedical industry due to their strong antioxidant properties. In the current study, we report the influence of nine different physical and chemical parameters: pH, aeration and, concentrations of MgSO(4), CaCl(2), KCl, natural organic matter, fructose, nanoparticles and Escherichia coli, on the antibacterial activity of dextran coated cerium oxide nanoparticles. A least-squares quadratic regression model was developed to understand the collective influence of the tested parameters on the anti-bacterial activity and subsequently a computer-based, interactive visualization tool was developed. The visualization allows us to elucidate the effect of each of the parameters in combination with other parameters, on the antibacterial activity of nanoparticles. The results indicate that the toxicity of CeO(2) NPs depend on the physical and chemical environment; and in a majority of the possible combinations of the nine parameters, non-lethal to the bacteria. In fact, the cerium oxide nanoparticles can decrease the anti-bacterial activity exerted by magnesium and potassium salts.

We predict that the presence of extended defects can reduce the mechanical strength of a ceria nanorod by 70%. Conversely, the pristine material can deform near its theoretical strength limit. Specifically, atomistic models of ceria nanorods have been generated with full microstructure, including: growth direction, morphology, surface roughening (steps, edges, corners), point defects, dislocations and grain-boundaries. The models were then used to calculate the mechanical strength as a function of microstructure. Our simulations reveal that the compressive yield strengths of ceria nanorods, ca. 10 nm in diameter and without extended defects, are 46 and 36 GPa for rods oriented along [211] and [110] respectively, which represents almost 10% of the bulk elastic modulus and are associated with yield strains of about 0.09. Tensile yield strengths were calculated to be about 50% lower with associated yield strains of about 0.06. For both nanorods, plastic deformation was found to proceed via slip in the {001} plane with direction ã??110ã?? - a primary slip system for crystals with the fluorite structure. Dislocation evolution for the nanorod oriented along [110] was nucleated via a cerium vacancy present at the surface. A nanorod oriented along [321] and comprising twin-grain boundaries with {111} interfacial planes was calculated to have a yield strength of about 10 GPa (compression and tension) with the grain boundary providing the vehicle for plastic deformation, which slipped in the plane of the grain boundary, with an associated ã??110ã?? slip direction. We also predict, using a combination of atomistic simulation and DFT, that rutile-structured ceria is feasible when the crystal is placed under tension. The mechanical properties of nanochains, comprising individual ceria nanoparticles with oriented attachment and generated using simulated self-assembly, were found to be similar to those of the nanorod with grain-boundary. Images of the atom positions during tension and compression are shown, together with animations, revealing the mechanisms underpinning plastic deformation. For the nanochain, our simulations help further our understanding of how a crystallising ice front can be used to 'sculpt' ceria nanoparticles into nanorods via oriented attachment. © 2011 The Royal Society of Chemistry.