scispace - formally typeset
Search or ask a question

Showing papers by "Thalappil Pradeep published in 2020"


Journal ArticleDOI
20 May 2020-ACS Nano
TL;DR: This Review presents the compelling need for providing access to clean water through nanotechnology-enabled solutions and large disparities in ensuring their implementation and suggests specific pointers and quantify the impact of such technologies.
Abstract: Sustainable nanotechnology has made substantial contributions in providing contaminant-free water to humanity. In this Review, we present the compelling need for providing access to clean water through nanotechnology-enabled solutions and the large disparities in ensuring their implementation. We also discuss the current nanotechnology frontiers in diverse areas of the clean water space with an emphasis on applications in the field and provide suggestions for future research. Extending the vision of sustainable and affordable clean water to environment in general, we note that cities can live and breathe well by adopting such technologies. By understanding the global environmental challenges and exploring remedies from emerging nanotechnologies, sustainability in clean water can be realized. We suggest specific pointers and quantify the impact of such technologies.

105 citations


Journal ArticleDOI
08 Apr 2020-ACS Nano
TL;DR: Electrochemical non-enzymatic glucose sensing ability of nickel-niobium (Ni60Nb40) amorphous alloys in alkaline medium is shown and, in nanoglass, a network of glassy interfaces, compared to melt-spun-ribbon, is plausibly responsible for the enhanced sensitivity.
Abstract: Despite being researched for nearly five decades, chemical application of metallic glass is scarcely explored. Here we show electrochemical nonenzymatic glucose-sensing ability of nickel-niobium (Ni60Nb40) amorphous alloys in alkaline medium. Three different Ni60Nb40 systems with the same elemental composition, but varying microstructures are created following different synthetic routes and tested for their glucose-sensing performance. Among melt-spun ribbon, nanoglass, and amorphous-crystalline nanocomposite materials, nanoglass showed the best performance in terms of high anodic current density, sensitivity (20 mA cm-2 mM-1), limit of detection (100 nM glucose), stability, reproducibility (above 5000 cycles), and sensing accuracy among nonenzymatic glucose sensors involving amorphous alloys. When annealed under vacuum, only the heat-treated nanoglass retained a similar electrochemical-sensing property, while the other materials failed to yield desired results. In nanoglass, a network of glassy interfaces, compared to melt-spun ribbon, is plausibly responsible for the enhanced sensitivity.

45 citations


Journal ArticleDOI
TL;DR: A metal-free novel route for the accelerated synthesis of benzimidazole and its derivatives in the ambient atmosphere using electrostatically charged microdroplets generated using a nano-electrospray (nESI) ion source is reported.
Abstract: We report a metal-free novel route for the accelerated synthesis of benzimidazole and its derivatives in the ambient atmosphere. The synthetic procedure involves 1,2-aromatic diamines and alkyl or aryl carboxylic acids reacting in electrostatically charged microdroplets generated using a nano-electrospray (nESI) ion source. The reactions are accelerated by orders of magnitude in comparison to the bulk. No other acid, base or catalyst is used. Online analysis of the microdroplet accelerated reaction products is performed by mass spectrometry. We provide evidence for an acid catalyzed reaction mechanism based on identification of the intermediate arylamides. Their dehydration to give benzimidazoles occurs in a subsequent thermally enhanced step. It is suggested that the extraordinary acidity at the droplet surface allows the carboxylic acid to function as a C-centered electrophile. Comparisons of this methodology with data from thin film and bulk synthesis lead to the proposal of three key steps in the reaction: (i) formation of an unusual reagent (protonated carboxylic acid) because of the extraordinary conditions at the droplet interface, (ii) accelerated bimolecular reaction because of limited solvation at the interface and (iii) thermally assisted elimination of water. Eleven examples are shown as evidence of the scope of this chemistry. The accelerated synthesis has been scaled-up to establish the substituent-dependence and to isolate products for NMR characterization.

41 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigate the adsorption of hexavalent uranium, U(VI), on phosphorylated cellulose nanofibers (PHO-CNF) and compare the results with those for native and TEMPO-oxidized nanocelluloses.
Abstract: We investigate the adsorption of hexavalent uranium, U(VI), on phosphorylated cellulose nanofibers (PHO-CNF) and compare the results with those for native and TEMPO-oxidized nanocelluloses. Batch adsorption experiments in aqueous media show that PHO-CNF is highly efficient in removing U(VI) in the pH range between 3 and 6. Gelling of nanofiber hydrogels is observed at U(VI) concentration of 500 mg/L. Structural changes in the nanofiber network (scanning and transmission electron microscopies) and the surface chemical composition (X-ray photoelectron spectroscopy) gave insights on the mechanism of adsorption. The results from batch adsorption experiments are fitted to Langmuir, Freundlich, and Sips isotherm models, which indicate a maximum adsorption capacity of 1550 mg/g, the highest value reported so far for any bioadsorbent. Compared to other metals (Zn, Mn, and Cu) and typical ions present in natural aqueous matrices the phosphorylated nanofibers are shown to be remarkably selective to U(VI). The results suggest a solution for the capture of uranium, which is of interest given its health and toxic impacts when present in aqueous matrices.

41 citations


Journal ArticleDOI
TL;DR: In this paper, an intercluster reaction leading to new trimetallic nanoclusters (NCs) using bimetallic and monometallic NCs as reactants is presented.
Abstract: Herein, we present an intercluster reaction leading to new trimetallic nanoclusters (NCs) using bimetallic and monometallic NCs as reactants. Dithiol protected bimetallic MAg28(BDT)12(PPh3)4 (BDT =...

38 citations


Journal ArticleDOI
21 Sep 2020
TL;DR: A cheap, handheld, portable mobile device for colorimetric detection and rapid estimation of F– in water by the application of the synthesized core–shell nanoparticles and a chemoresponsive dye and the sensor performs better than what was reported by prior works on aqueous F– sensing.
Abstract: Higher levels of fluoride (F-) in groundwater constitute a severe problem that affects more than 200 million people spread over 25 countries. It is essential not only to detect but also to accurately quantify aqueous F- to ensure safety. The need of the hour is to develop smart water quality testing systems that would be effective in location-based real-time water quality data collection, devoid of professional expertise for handling. We report a cheap, handheld, portable mobile device for colorimetric detection and rapid estimation of F- in water by the application of the synthesized core-shell nanoparticles (near-cubic ceria@zirconia nanocages) and a chemoresponsive dye (xylenol orange). The nanomaterial has been characterized thoroughly, and the mechanism of sensing has been studied in detail. The sensor system is highly selective toward F- and shows unprecedented sensitivity in the range of 0.1-5 ppm of F-, in field water samples, which is the transition regime, where remedial measures may be needed. It addresses multiple issues expressed by indicator-based metal complexes used to determine F- previously. Consistency in the performance of the sensing material has been tested with synthetic F- standards, water samples from F- affected regions, and dental care products like toothpastes and mouthwash using a smartphone attachment and by the naked eye. The sensor performs better than what was reported by prior works on aqueous F- sensing.

30 citations


Journal ArticleDOI
TL;DR: In this paper, host-guest complexes of atomically precise noble metal nanoparticles with cucurbit[7]uril (CB) in water were presented, specifically concentrating on Ag29(LA)12 (where LA is α-lipoic acid).
Abstract: We present an example of host–guest complexes of atomically precise noble metal nanoparticles with cucurbit[7]uril (CB) in water, specifically concentrating on Ag29(LA)12 (where LA is α-lipoic acid...

26 citations


Journal ArticleDOI
TL;DR: This study is the first ultrafast spectroscopic probe of a ligand-protected coinage metal cluster in isolation and will be interesting to study how cluster size, overall charge state or heteroatom doping can be used to tune the corresponding relaxation dynamics in the absence of solvent.
Abstract: The photophysics of the isolated trianion Ag29(BDT)123– (BDT = benzenedithiolate), a ligand-protected cluster comprising BDT-based ligands, terminating a shell of silver thiolates and a core of sil...

25 citations


Journal ArticleDOI
TL;DR: The magnetic‐field‐induced splitting of ferrofluid droplets immersed in an immiscible liquid is presented, and related fascinating dynamics and applications are discussed.
Abstract: Ferrofluids exhibit a unique combination of liquid properties and strong magnetic response, which leads to a rich variety of interesting functional properties. Here, the magnetic-field-induced splitting of ferrofluid droplets immersed in an immiscible liquid is presented, and related fascinating dynamics and applications are discussed. A magnetic field created by a permanent magnet induces instability on a mother droplet, which divides into two daughter droplets in less than 0.1 s. During the splitting process, the droplet undergoes a Plateau-Rayleigh-like instability, which is investigated using high-speed imaging. The dynamics of the resulting satellite droplet formation is shown to depend on the roughness of the supporting surface. Further increasing the field results in additional splitting events and self-assembly of microdroplet populations, which can be magnetically actuated. The effects of magnetization and interfacial tension are systematically investigated by varying magnetic nanoparticles and surfactant concentrations, and a variety of outcomes from labyrinthine patterns to discrete droplets are observed. As the splitting process depends on interfacial tension, the droplet splitting can be used as a measure for interfacial tension as low as 0.1 mN m-1. Finally, a population-based digital microfluidics concept based on the self-assembled microdroplets is presented.

23 citations


Journal ArticleDOI
TL;DR: In this paper, a cellulose nanofiber-polyaniline (PANI)-templated ferrihydrite nanocomposite synthesized by a green one-pot process where the iron precursor not only acts as an oxidant for the polymerization of aniline to give emaraldine base-emaraldines salt (EB-ES) form of PANI but also forms 2-line ferri hydrite (FeOOH) nanoparticles in situ.
Abstract: Fluoride (F–) is one of the common naturally occurring anions present in groundwater worldwide that may be beneficial or detrimental depending on the total amount ingested and the duration of exposure. Among all the remediation techniques, adsorption using nanomaterials shows superior efficiency and the process can be eco-friendly and economical. We report cellulose nanofiber-polyaniline (PANI)-templated ferrihydrite nanocomposite synthesized by a green one-pot process where the iron precursor not only acts as an oxidant for the polymerization of aniline to give emaraldine base–emaraldine salt (EB–ES) form of PANI but also forms 2-line ferrihydrite (FeOOH) nanoparticles in situ. These nanoparticles get embedded into the cellulose–PANI blend to give a granular nanocomposite having double action sites for adsorption and robustness which also prevent nanoparticle leaching. Doped PANI and FeOOH act as synergistic adsorption sites for F– removal which results in an enhanced uptake capacity. The materials’ adso...

20 citations


Journal ArticleDOI
TL;DR: In this paper, molecularly charged electrospun nanofibers obtained by soft chemical treatment for the capture of particulate matter (PM) were used for filtering polluted air using various filtration media.
Abstract: We introduce molecularly charged electrospun nanofibers obtained by soft chemical treatment for the capture of particulate matter (PM). These PMs, along with certain volatile organic compounds (VOCs), pose a severe threat not only to human health but also to the environment. As the concentrations of these PMs have been steadily increasing in the Southeast Asian countries, a dire need for protection against these particles is warranted. Filtering out the polluted air using various filtration media, such as face masks and nasal filters, has been the standard method for minimizing exposure to PM. Here, we demonstrate the removal of PM and VOCs by utilizing electrospun nanofibers of polystyrene (PS) and polyacrylonitrile (PAN) with molecular charges imparted on them via chemical treatment. The chemically treated fibers were successful in capturing even particles measuring 300 nm, which are considered to be the most penetrable particles. We report a filtration efficiency of ∼93% for removing such particles, which is ∼3 ± 1.5% enhancement when compared to the untreated fibers. The fibers have been subjected to extreme haze conditions (∼1413 μg m–³) of PM₂.₅ for a duration of 1 h, and the filtration efficiency was measured to be ∼99.01%. These fibers also possess the capability to capture model VOCs such as aniline, toluene, tetrahydrofuran, and chloroform. When PAN, PS, and their chemically treated counterparts were tested for their antibacterial activity, these filter mats had bactericidal effect on Escherichia coli, Bacillus subtilis, and Enterococcus faecalis. A nasal plug hosting these filter mats has been designed, which can offer personal protection from PM. Enhanced removal of residual particles is extremely important, and this difficult task is made possible with our approach. The efficiency of our approach is due to the charged nature of PM, especially of the smaller size regime.

Journal ArticleDOI
TL;DR: Evidence of possible synergism between arsenic and OPs in association with prevalence of diabetes, pre-diabetes and atherosclerosis in the study population is observed.
Abstract: Authors would like to correct the error in the online publication, which is mentioned below.

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a method for the self-assembly of monodispersed atomically precise monolayer-protected noble metal clusters (CASs) formed by self-assembling monodiscrete solids.
Abstract: Cluster-assembled solids (CASs) formed by the self-assembly of monodispersed atomically precise monolayer-protected noble metal clusters are attractive due to their collective properties. The physi...

Journal ArticleDOI
TL;DR: It is suggested that enhanced mobility or diffusion of water molecules during acetone hydrate dissociation enabled crystallization, and this finding implied that CHs might exist in extreme low-pressure environments present in the comets.
Abstract: Cubic ice (ice Ic) is a crystalline phase of solid water, which exists in the earth’s atmosphere and extraterrestrial environments. We provide experimental evidence that dissociation of acetone cla...

Book ChapterDOI
01 Jan 2020
TL;DR: In this paper, the authors give a perspective on sustainable nanoscale engineering through the view of numerous academic and industrial experts. But, their focus is on the sustainable development goals set by the United Nations, which are a blueprint for a thriving and more sustainable future for all.
Abstract: Nanotechnology and nanomaterials are among the most significant scientific and industrial research breakthroughs of the 21st century. With the rapid globalization of science, chemists, materials scientists, and chemical engineers are synergistically working together worldwide to understand how to manipulate matter for the benefit of humankind. The Sustainable Development Goals set by the United Nations provide a blueprint through which a thriving and more sustainable future can be achieved for all. These goals address the global challenges we face, and most of them are directly affected by chemical manufacturing. Consequently, it is our responsibility to design, manufacture and recycle chemicals, and develop processes, considering sustainability. There are several emerging areas of nanoscale engineering with great promise for sustainable chemical engineering. There are a plethora of innovative materials and methodologies, all with the potential to enable sustainable industrial development, on the rise. This chapter gives a perspective on sustainable nanoscale engineering through the view of numerous academic and industrial experts.

Journal ArticleDOI
TL;DR: For the first time, spontaneous reactions between an atomically precise NC, Au25(PET)18, and polydispersed silver NPs with an average diameter of 4 nm and protected with PET are demonstrated, resulting in alloy NPs under ambient conditions.
Abstract: Reactions between atomically precise noble metal nanoclusters (NCs) have been studied widely in the recent past, but such processes between NCs and plasmonic nanoparticles (NPs) have not been explored earlier. For the first time, we demonstrate spontaneous reactions between an atomically precise NC, Au25(PET)18 (PET = 2-phenylethanethiol), and polydispersed silver NPs with an average diameter of 4 nm and protected with PET, resulting in alloy NPs under ambient conditions. These reactions were specific to the nature of the protecting ligands as no reaction was observed between the Au25(SBB)18 NC (SBB = 4-(tert-butyl)benzyl mercaptan) and the very same silver NPs. The mechanism involves an interparticle exchange of the metal and ligand species where the metal-ligand interface plays a vital role in controlling the reaction. The reaction proceeds through transient Au25-xAgx(PET)n alloy cluster intermediates as observed in time-dependent electrospray ionization mass spectrometry (ESI MS). High-resolution transmission electron microscopy (HRTEM) analysis of the resulting dispersion showed the transformation of polydispersed silver NPs into highly monodisperse gold-silver alloy NPs which assembled to form 2-dimensional superlattices. Using NPs of other average sizes (3 and 8 nm), we demonstrated that size plays an important role in the reactivity as observed in ESI MS and HRTEM.

Journal ArticleDOI
TL;DR: This is the first report on dual emitting pyrene protected atomically precise silver nanocluster, and it showed blue emission under UV light due to pyrene to metal core charge-transfer, and NIR emission due to charge- transfer within the metal core.


Journal ArticleDOI
TL;DR: In this paper, the authors report fullerene (C60 and C70)-induced aggregation of atomically precise clusters, taking M25(SR)18− (M = Ag, Au and −SR is a thiolate ligand) clusters as an example.
Abstract: We report fullerene (C60 and C70)-induced aggregation of atomically precise clusters, taking M25(SR)18– (M = Ag, Au and −SR is a thiolate ligand) clusters as an example. We show that dimers, trimer...

Journal ArticleDOI
TL;DR: A dithiol-protected silver cluster, Ag14(BDT)6(PPh3)8 (BDT = 1,2-benzene dithol), abbreviated as Ag14DT, which exhibits distinctly different optical properties than the analogous monothi...
Abstract: We report a dithiol-protected silver cluster, Ag14(BDT)6(PPh3)8 (BDT = 1,2-benzene dithiol), abbreviated as Ag14DT, which exhibits distinctly different optical properties than the analogous monothi...

Journal ArticleDOI
TL;DR: In this paper, the synthesis of two new hydride and phosphine coprotected clusters was reported, which were used for the first time to synthesize hydrides and phosphines.
Abstract: Here, we report the synthesis of two new hydride and phosphine coprotected clusters [Ag15H13(DPPH)5]2+ (DPPH = 1,6-bis(diphenylphosphino)hexane) and [Ag27H22(DPPB)7]3+ (DPPB = 1,4-bis(diphenylphosp...

Journal ArticleDOI
TL;DR: In this article, subtle changes in the molecular orientations of different thiols upon interaction with soft-landed silver nanoparticles (AgNPs) have been probed using the technique called ambient electrosp...
Abstract: Herein, subtle changes in the molecular orientations of different thiols upon interaction with soft-landed silver nanoparticles (AgNPs) have been probed using the technique called ambient electrosp...

Journal ArticleDOI
19 Oct 2020
TL;DR: The growing emission of CO2 is a severe cause of concern due to its adverse impact on the environment and climate change worldwide as discussed by the authors, and various approaches, including synthesis of porous ma...
Abstract: The growing emission of CO2 is a severe cause of concern due to its adverse impact on the environment and climate change worldwide. In the past, various approaches, including synthesis of porous ma...

Journal ArticleDOI
20 Jul 2020
TL;DR: In this paper, a brass-coated steel cord is embedded in a rubber compound in radial tires (beneath the tread) to give stability and strength to the cord.
Abstract: Brass (which is an alloy of copper and zinc)-coated steel cords (BCSCs) in the form of belts are embedded in a rubber compound in radial tires (beneath the tread) to give stability and strength to ...

Journal ArticleDOI
TL;DR: Among T2DM patients from south-coastal Andhra Pradesh the prevalence of thyroid dysfunction, especially that of SCH was high; SCH was more frequent among obese and nonmetformin users and was associated with increased risk of diabetic retinopathy.
Abstract: Background and aims To study the prevalence of thyroid disorders and their association with microvascular complications among adult type 2 diabetes mellitus (T2DM) patients from south-coastal Andhra Pradesh, India Methods This cross-sectional study included 500 subjects with T2DM and was conducted in a tertiary health care center from south-coastal Andhra Pradesh. Participants previously diagnosed with thyroid disorders were excluded from the study. Results Thyroid dysfunction was observed in 98 (19.6%) subjects of which subclinical hypothyroidism (n = 66, 13.2%) was the most common. Subclinical hypothyroidism (SCH) was more frequent in obese patients (16.2% vs 7.6%, p = 0.007) and metformin users (9.6% vs 18.7%, p = 0.0044). Diabetic retinopathy (27.3% vs 8.9%, p = 0.001) was significantly more frequent in SCH patients than euthyroid T2DM patients. Conclusion Among T2DM patients from south-coastal Andhra Pradesh the prevalence of thyroid dysfunction, especially that of SCH was high; SCH was more frequent among obese and nonmetformin users and was associated was associated with increased risk of diabetic retinopathy.


Journal ArticleDOI
17 Feb 2020-Analyst
TL;DR: This study demonstrates a systematic flow rate dependent study of three different aliphatic ligand protected Au25 clusters, with three commercially available alkyl and aryl functionalized reversed-phase HPLC columns, as they represent the variations encountered commonly.
Abstract: The synthesis of atomically precise noble metal clusters using various protocols often results in a mixture of clusters with different cores. Hence, it is important to isolate such clusters in their pure form in terms of composition especially for crystallization. High-performance liquid chromatography (HPLC) is a powerful tool to achieve this. The interaction of ligands with column functionalities determine the extent of separation and their stability under conditions used. We demonstrate a systematic flow rate dependent study of three different aliphatic ligand protected Au25 clusters, with three commercially available alkyl and aryl functionalized reversed-phase HPLC columns, as they represent the variations encountered commonly. Molecular docking simulations were carried out to understand the interactions between the stationary phase and the cluster surface. These investigations enabled the selection of an appropriate column for better separation of structurally different ligand protected clusters. High-resolution separation of anionic and neutral Au25 clusters was acheived with a selectivity (α) of 1.2 by tuning the chromatographic conditions. This study would provide new insights in developing better methods for the efficient separation of monolayer protected clusters.

Journal ArticleDOI
TL;DR: The first example of acetylide protected silver clusters by a reaction between Ag17+ and acetylene, conducted around atmospheric pressure is presented, which may be helpful to design new catalysts useful in organometallic chemistry.


Journal ArticleDOI
TL;DR: The study shows that the interaction of Fe and CO results in a Fe-CO complex that reacts in the presence of excess CO at cryogenic conditions leading to CO2, which may have astrochemical importance in interstellar ices, containing CO.
Abstract: Catalytic conversion of CO to CO2 has been investigated in ultrahigh vacuum (UHV) under cryogenic conditions (10 K). This cryogenic oxidation is assisted by iron upon its co-deposition with CO, on a substrate. The study shows that the interaction of Fe and CO results in a Fe-CO complex that reacts in the presence of excess CO at cryogenic conditions leading to CO2. Here, the presence of CO on the surface is a prerequisite for the reaction to occur. Different control experiments confirm that the reaction takes place in the condensed phase and not in the gas phase. Surface sensitive reflection absorption infrared spectroscopy (RAIRS), temperature programmed desorption (TPD), and Cs+ based low energy ion scattering are utilized for this study. The iron assisted formation of CO2 may be proposed as another pathway relevant in interstellar ices, containing CO. This direct oxidation process, which occurs at extremely low temperatures and pressures, in the presence of a reactive metal species like iron (the most abundant metal in the interstellar medium) may have astrochemical importance. It does not require any external energy in the form of photo-irradiation or thermal processing. Such reactions are highly relevant in cold dense molecular clouds where interactions between neutral species are more favoured.