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Herein we describe and discuss the effect of significant advantages of the alkaline earth fluoride additive SrF2 on the improvement of the kinetics, thermodynamics, and cyclability of the frontier hydrogen storage material MgH2. Strontium fluoride, SrF2, which has been used as an additive for the first time in the present study, has an elemental electronegativity difference of 3.04 (the highest amongst the fluorides) as compared to 2.38 for NbF5, one of the best-known catalysts so far for MgH2. Therefore, SrF2 is highly ionic and will readily react with MgH2, which is not only ionic but also has a polar covalent character. SrF2 reacts with MgH2 to yield magnesium fluoride (MgF2) and strontium hydride (SrH2) which act as catalysts. The present investigations have revealed that both (MgF2 + SrH2) and their graphene templated version, (MgF2 + SrH2)@Gr, work as better catalysts for MgH2 than NbF5. Thus the desorption of H2 from ball-milled MgH2 catalyzed by (MgF2 + SrH2) corresponds to 5.30 wt% in 15 min, and for (MgF2 + SrH2)@Gr the desorption is 6.01 wt% in 15 min at 290 °C. Also, the onset desorption temperatures for MgH2 with (MgF2 + SrH2) and (MgF2 + SrH2)@Gr catalysts are 261 °C and 231 °C, respectively, which are 95 °C and 125 °C lower than that for ball-milled MgH2. The H2 absorption for (MgF2 + SrH2) catalyzed MgH2 is found to be 6.00 wt% in 5 min at 290 °C. For (MgF2 + SrH2)@Gr catalyzed MgH2 the hydrogen absorption is 6.16 wt% in 2 min at 290 °C. The change in desorption enthalpy for MgH2–(MgF2 + SrH2)@Gr is 67.60 kJ mol−1 as compared to 74.84 kJ mol−1 for MgH2–(MgF2 + SrH2). The storage capacity for MgH2–(MgF2 + SrH2)@Gr remains ∼6.00 wt% even after 15 cycles, which corresponds to excellent cyclability. A feasible catalytic mechanism arising from (MgF2 + SrH2) and (MgF2 + SrH2)@Gr catalysts on hydrogen sorption in MgH2 has been proposed based on X-ray diffraction, Raman spectroscopy, Fourier transmission infrared spectroscopy, and transmission/scanning electron microscopic studies. The present study is the first of its type where absorption/desorption kinetics, thermodynamics, and cyclability for MgH2 have all been improved by the use of the single additive SrF2 and the derived catalyst MgF2 + SrH2.

In this paper, we report here the hydrogen storage capacity of activated carbon aerogel synthesized by ambient pressure drying using a new catalyst. The carbon aerogel (CA) has been synthesized by the sol-gel method using resorcinol (R) and formaldehyde (F). For drying of RF wet gel instead of expensive and unsafe supercritical process, we have used ambient pressure drying. To avoid shrinkage which may occur due to this mode of drying, instead of usual catalyst (C): Na2CO3, organic catalyst triethylamine (TEA), which is known to be a condensing agent has been used. In order to find out the effect of change of R/C ratio on hydrogen sorption, three different R/C namely CA 1000, CA 2000, and CA 3000 were taken. Structural and microstructural details have been studied employing XRD, SEM, TEM, nitrogen adsorption, FTIR, and Raman spectroscopy. TEM and nitrogen adsorption studies have revealed that aerogel with R/C 1000 exhibits a higher degree of micropore density. The hydrogen storage capacities for all R/C ratios have been determined. It has been found that carbon aerogel (CA) with R/C = 1000, exhibits the highest hydrogen adsorption capacity out of the three aerogels. At liquid nitrogen temperature, the hydrogen storage capacity of aerogel with R/C = 1000 for the as-synthesized and activated carbons have been found to be 4.00 wt % and 4.80 wt %. A viable reason for the occurrence of high hydrogen storage capacity at liquid nitrogen temperature for aerogel with R/C = 1000 has been put forward.

In the present investigation, we have reported the surface-microstructure, chemical composition and structural characteristics of the conventionally solidified Al65Cu15Co20 and Al65Cu20Co15 decagonal quasicrystals before and after chemical leaching treatment. The surface of the polycrystalline Al–Cu–Co decagonal phase was leached with 2.5 mol of Na2CO3 solution for the duration of 0.5 h, 2 h and 8 h. The leached surface was characterized by x-ray diffraction, scanning and transmission electron microscopy techniques. The energy dispersive x-ray analysis was employed to determine the chemical composition of the leached surface. After leaching treatment, the crystallographic structure of the leached surface was found to change from the quasicrystalline phase to the crystalline phases of Cu, Co and their oxides. The formation of the skeletal structure observed at the surface was attributed to the removal of Al atoms from the lattice points of the concerned decagonal quasilattice. This skeletal structure was found to contain porosities coexisting with finely distributed nano-particles of Cu, Co and Cu2O with sizes ranging from 10 to 28 nm. The 8 h leached surface containing these skeletal features has demonstrated excellent catalytic activity for steam reforming of methanol and it has led to hydrogen production at the rate of ~200 ml/g min at the reaction temperature of 580 K.

The present investigation reports the effect of TiH2 templated over graphene (TiH2@Gr) on the hydrogen sorption characteristics of MgH2/Mg. The as synthesized TiH2@Gr leads to significant effect on sorption in MgH2 by the following effects: the first is dehydrogenation of MgH2–TiH2@Gr, which leads to the conversion of some part of TiH2 into TiH1.924. TiH2 together with TiH1.924 works as a better catalyst than TiH2 alone. The second is ball-milling of TiH2@Gr, which produces defective graphene, which also works as co-catalyst. The third is anchoring of TiH2 on graphene, which does not allow the catalyst to agglomerate. The catalytic effect of TiH2@Gr on MgH2 is found to be better than Ti@Gr and TiO2@Gr. The onset desorption temperature for MgH2–TiH2@Gr is ~204 °C, which is 31 °C and 36 °C lower than MgH2–Ti@Gr, MgH2–TiO2@Gr respectively. The better catalytic behavior of TiH2@Gr also persists during de/re-hydrogenation kinetics and cycling study of MgH2. The feasible mechanism for superior catalytic for TiH2@Gr on MgH2 has been put forward.

The present investigation deals with the synthesis of ternary transition metal alloy nanoparticles of FeCoNi and graphene templated FeCoNi (FeCoNi@GS) by one-pot reflux method and there use as a catalyst for hydrogen sorption in MgH2. It has been found that the MgH2 catalyzed by FeCoNi@GS (MgH2: FeCoNi@GS) has the onset desorption temperature of ~255 °C which is 25 °C and 100 °C lower than MgH2 catalyzed by FeCoNi (MgH2: FeCoNi) (onset desorption temperature 280 °C) and the ball-milled (B.M) MgH2 (onset desorption temperature 355 °C) respectively. Also MgH2: FeCoNi@GS shows enhanced kinetics by absorbing 6.01 wt% within just 1.65 min at 290 °C under 15 atm of hydrogen pressure. This is much-improved sorption as compared to MgH2: FeCoNi and B.M MgH2 for which hydrogen absorption is 4.41 wt% and 1.45 wt% respectively, under the similar condition of temperature, pressure and time. More importantly, the formation enthalpy of MgH2: FeCoNi@GS is 58.86 kJ/mol which is 19.26 kJ/mol lower than B.M: MgH2 (78.12 kJ/mol). Excellent cyclic stability has also been found for MgH2: FeCoNi@GS even up to 24 cycles where it shows only negligible change from 6.26 wt% to 6.24 wt%. A feasible catalytic mechanism of FeCoNi@GS on MgH2 has been put forward based on X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Photoelectron Spectroscopy (XPS), and microstructural (electron microscopic) studies.

The present study is focused on the structural correlation of magneto-electric coupling that exists in polycrystalline TbMnO 3 . The X-ray diffraction patterns are collected at various conditions, which are (1) at 300 K without a magnetic field, (2) at 2 K without magnetic field and (3) at 2 K with 7 Tesla magnetic fields. The structural transition in TbMnO 3 has been observed at 2 K and some lattice modulation after applying the magnetic field at 2 K. The Rietveld refinement of TbMnO 3 confirms the orthorhombic phase with centrosymmetric space group Pnma at 300 K. We have observed that the inversion symmetry breaks at 2 K and the polycrystalline TbMnO 3 has been refined using a non-centrosymmetric orthorhombic space group which can be either Pn2 1 a or P2 1 ma. This structural transition confirms the presence of a ferroelectric phase at 2 K. After the application of 7 Tesla magnetic field, the signature of an incommensurate phase has been observed in polycrystalline TbMnO 3 at 2 K. The DC magnetization behaviour with temperature M(T) and field M(H) reveals the antiferromagnetic behaviour of polycrystalline TbMnO3 below 42 K. We have also measured magneto-dielectric property of polycrystalline TbMnO 3 at the low temperature, which confirms the strong magneto-electric coupling in polycrystalline TbMnO 3 below the transition temperature.

Diabetes mellitus Type 2 happens to be one of the most challenging health concerns in recent times and has spiked an alarming rise taking it into epidemic category. For management of this epidemic, sulphonylureas have been cornerstone in its treatment. The inefficiency and impairment of insulin to function has been compensated by treatment with anti-hyperglycemic agents (glibenclamide). However, this has been linked with cases of hypoglycemia. In order to rectify this, the present study focuses on development of better drug analogue. Sulphonylurea receptor (SUR1) was modeled with reliable efficiency and confirmed for structural validation. The docking results were strongly supported by molecular dynamics data and molecular mechanics-generalized born surface area (MM-GBSA) calculations. Successful docking of predicted sulphonylurea receptor with designed analogue (C24H26ClN3O4S) was illustrated with stronger binding energy (− 8.3 kcal/mol) having seven hydrophobic contacts and two hydrogen bonds (Ile103and Leu116) with the receptor protein. In case of SUR1-glibenclamide complex, a binding energy of − 7.1 kcal/mol was contributed from four hydrophobic contacts and three hydrogen bonds. The predicted molecule when scrutinized for pharmacophore and QSAR properties, like polar surface area, molar refractivity, oral bioavailability, solubility, transport across the gut, resistance to blood brain barrier and intestinal absorption, showed values mostly falling in prescribed range. It also highlighted that the inhibitor is non-toxic and non-carcinogenic property. Therefore, C24H26ClN3O4S can be used as a better and potent drug for treatment of diabetes Type 2 in comparison to glibenclamide.

We describe the synthesis of MgH2 using autocatalytic effect of MgH2. The MgH2 was synthesized by ball milling Mg with 5 wt% of MgH2. The ball milling was carried out at different pressures of 15, 30 and 45 atm of H2 followed by heat treatment (heating under vacuum and annealing at 30 atm of H2 pressure (at 350 °C) for 10 h). It has been found that the MgH2 synthesized using 30 atm of H2 pressure during ball milling, followed by heat treatment and annealing (MgH230BM) is the optimum material as it has lowest desorption temperature (325 °C) faster rehydrogenation kinetic (6.60 wt% within 30 min at 300 °C and 20 atm hydrogen pressure). Also MgH230BM maintains the storage capacity of more than 6.00 wt% (loss of 0.6 wt%) after 10 cycles of de/re-hydrogenation. The as synthesized MgH2 has superior de/re-hydrogenation properties and is ∼4 times cheaper as compared to MgH2 procured from the chemical company like Alfa-Aesar. It is to be mentioned that under above mentioned temperature and pressure conditions the stand alone Mg (without having MgH2 as catalyst) doesnot at all converts to MgH2. The present study opens the gateway for economical synthesis of MgH2 at large scale.

Three different high entropy-alloys consisting of six elements (Ti, Zr, V, Cr, Ni, and Fe) with varying Fe content were synthesized by using the RF induction melting technique. All the as-cast, slow-cooled, and rapidly quenched alloys exhibit C14 Laves phase, and it is found to be stable at high temperature. A lattice contraction has been observed with the addition of Fe. To the best of our knowledge, this is the first report on the synthesis of a single-phase high-entropy complex intermetallic compound in the hexanary alloy system. It has been shown that the thermodynamic calculations following Miedema’s approach and the parametric approach utilizing several descriptors comprising configurational entropy, mixing enthalpy, atomic size mismatch, electronegativity, and valence electron concentration favor the stability of the high-entropy multicomponent Laves phase.

The present study deals with the material tailoring of Mg(NH2)2–2LiH through dual borohydrides: the reactive LiBH4 and the non-reactive NaBH4. Furthermore, a pulverizer, as well as a catalyst FeTi, has been added in order to facilitate hydrogen sorption. Addition of LiBH4 to LiNH2 in a 1 : 3 molar ratio leads to the formation of Li4(BH4)(NH2)3 which also acts as a catalyst. However, the addition of NaBH4 doesn't lead to any compound formation but shows a catalytic effect. The onset dehydrogenation temperature of thermally treated Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4) is 142 °C as against 196 °C for the basic material Mg(NH2)2–2LiH. However, with the FeTi catalyzed Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4, it has been reduced to 120 °C. This is better than other similar amide/hydride composites where it is 149 °C (when the basic material is catalyzed with LiBH4). The FeTi catalyzed Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4 sample shows better de/re-hydrogenation kinetics as it desorbs 3.9 ± 0.04 wt% and absorbs nearly 4.1 ± 0.04 wt% both within 30 min at 170 °C (with the H2 pressure being 0.1 MPa for desorption and 7 MPa for absorption). The eventual hydrogen storage capacity of Mg(NH2)2–2LiH/(Li4(BH4)(NH2)3–NaBH4 together with FeTi has been found to be ∼5.0 wt%. To make the effect of catalysts intelligible, we have put forward in a schematic way the role of Li and Na borohydrides with FeTi for improving the hydrogen sorption properties of Mg(NH2)2–2LiH.

Visceral leishmaniasis (VL) is still a major public health concern in developing countries having the highest outbreak and mortality potential. While the treatment of VL has greatly improved in recent times, the current diagnostic tools are limited for use in the post-elimination setting. Although conventional serological methods of detection are rapid, they can only differentiate between active disease in strict combination with clinical criteria, and thus are not sufficient enough to diagnose relapse patients. Therefore, there is a dire need for a portable, authentic, and reliable assay that does not require large space, specialized instrument facilities, or highly trained laboratory personnel and can be carried out in primary health care settings. Advances in the nanodiagnostic approaches have led to the expansion of new frontiers in the concerned area. The nanosized particles are blessed with an ability to interact one-on-one with the biomolecules because of their unique optical and physicochemical properties and high surface area to volume ratio. Biomolecular detection systems based on nanoparticles (NPs) are cost-effective, rapid, nongel, non-PCR, and nonculture based that provide fast, one-step, and reliable results with acceptable sensitivity and specificity. In this review, we discuss different NPs that are being used for the identification of molecular markers and other biomarkers, such as toxins and antigens associated with leishmaniasis. The most promising diagnostic approaches have been included in the article, and the ability of biomolecular recognition, advantages, and disadvantages have been discussed in detail to showcase the enormous potential of nanodiagnostics in human and veterinary medicine. This article is categorized under: Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease Diagnostic Tools > Biosensing.

Visceral leishmaniasis (VL) has been a major health concern in the developing world, primarily affecting impoverished people. It is caused by a protozoan parasite Leishmania donovani and is characterized by immune dysfunction that can lead to deadly secondary infections. Several adverse side effects limit the existing treatment options; hence, the need of the hour is some drug option with high efficacy and no toxicity. To make targeted delivery of Amphotericin B (AmB), we have used amine-functionalized versions of carbon nanostructures, namely f-CNT and f-Graphene (f-Grap). The results with f-Grap-AmB, because of a much larger surface area, were expected to be better. However, the results obtained by us showed only marginal improvement (IC50 f-Grap-AmB; 0.0038 ± 0.00119 μg/mL). This is, in all likelihood, due to the agglomeration effect of f-Grap-AmB, which is invariably obtained with graphene. To resolve this issue, we have synthesized a graphene-CNT composite (graphene 70% and CNT 30% by weight). Because CNT is dispersed in between graphene sheets, the agglomeration effect is avoided, and our study suggests that the f-Composite-AmB (f-Comp-AmB) showed no toxicity against the murine J774A.1 macrophage cell line and did not induce any hepatic or renal toxicity in Swiss albino mice. The f-Comp-AmB also showed a remarkable elevation in the in vitro and in vivo antileishmanial efficacy in comparison to AmB and f-CNT-AmB or f-Grap-AmB in J774A.1 and Golden Syrian hamsters, respectively. Additionally, we have also observed that the percentage suppression of parasite replication in the spleen of the hamster was significantly higher in the f-Comp-AmB (97.79 ± 0.2375) treated group in comparison with the AmB (85.66 ± 1.164) treated group of hamsters. To conclude, f-Comp-AmB could be a safe and reliable therapeutic option over the other carbon-based nanoparticles (NPs), i.e., f-CNT-AmB, f-Grap-AmB, and conventional AmB.

We report a mechanism for how low concentrations of TiH2 can function as a dynamic additive for improving both the kinetics and the thermodynamics of the Mg/MgH2–TiH2 system. We use a combination o...

The bio-waste coconut husk was converted into activated carbon through merely treating with KOH and thus obtained activated carbon was characterized by XRD, TGA, SEM and TEM analysis. The prepared activated carbon having very high surface area (1448 m 2 /g) was utilized as an adsorbent for the removal of fluoride (F - ) from water. Fluoride adsorption experiments were performed on the laboratory-scale column at different bed height, flow rates, and F - concentrations to explore the potential of prepared adsorbent and it was found to be very efficient adsorbent as it showed high adsorption capacity 6.5 mg/g at pH 5, F - concentration 10 mg/L and adsorbent dose 1.4 g/L. Various breakthrough models i.e. Bed Depth Service Time (BDST), Thomas and Yoon–Nelson were applied on breakthrough data to analyze the breakthrough curves. The high R 2 values obtained for the BDST model revealed its validity for this adsorption system. Breakthrough curves were successfully analyzed and described by both Thomas and Yoon–Nelson models. The exhausted adsorbent was efficiently regenerated with the 10% NaOH solution and regenerated adsorbent showed remarkable uptake capacity with a slight reduction in adsorption performance up to the 3 cycles. Life factor calculation indicated that adsorbent bed would have sufficient bed capacity up to 8.3 cycles to avoid breakthrough at time t = 0 and the bed would be completely exhausted after 9.0 cycles.

We report the exotic photoluminescence (PL) behaviour of 3D topological insulator Bi2Te3 single crystals grown by customized self-flux method and mechanically exfoliated few layers (18 plus minus 2 nm)/thin flakes obtained by standard scotch tape method from as grown Bi2Te3 crystals.The experimental PL studies on bulk single crystal and mechanically exfoliated few layers of Bi2Te3 evidenced a broad red emission in the visible region. These findings are in good agreement with our theoretical results obtained using the ab initio density functional theory framework., Main MS (17 Pages text including 4 Figs): Suppl. info. (4 pages); Accepted Scientific Reports

Stability of enzymes is an important parameter for their industrial applicability. Here, we report successful immobilization of β-amylase (bamyl) from peanut (Arachis hypogaea) onto Graphene oxide-carbon nanotube composite (GO-CNT), Graphene oxide nanosheets (GO) and Iron oxide nanoparticles (Fe3O4). The Box-Behnken Design of Response Surface Methodology (RSM) was used which optimized parameters affecting immobilization and gave 90%, 88% and 71% immobilization efficiency, respectively, for the above matrices. β-Amylase immobilization onto GO-CNT (bamyl@GO-CNT) and Fe3O4 (bamyl@Fe3O4), resulted into approximately 70% retention of activity at 65 °C after 100 min of exposure. We used atomic force microscopy (AFM), scanning and transmission electron microscopy (SEM and TEM), Fourier transformed infrared (FT-IR) spectroscopy and fluorescence microscopy for characterization of free and enzyme bound nanostructures (NS). Due to the non-toxic nature of immobilization matrices and simple but elegant immobilization procedure, these may have potential utility as industrial biocatalysts for production of maltose.

In this work, we report the synthesis of cuprous oxide (Cu2O) nanoparticles modified vertically oriented aligned titanium dioxide (TiO2) nanotube arrays through wet chemical treatment of TiO2 nanotubes and their multi-functional application as enhanced photo electrochemical and hydrogen generation. The synthesized samples were characterized by X-ray diffraction, SEM, TEM, and UV–Vis spectroscopy. The structural characterization revealed that the admixed Cu2O nanoparticles on the TiO2 surface did not alter its crystalline structure of vertically oriented aligned TiO2 nanotube. The photocatalytic performance and hydrogen generation of as synthesized Cu2O nanoparticles modified aligned TiO2 nanotube was found to highly depend on the Cu2O content. The optical characterizations reveal that the presence of Cu2O nanoparticles extends its absorption into the visible region which improves the photocurrent density in comparison to pristine aligned TiO2 nanotubes electrodes due to enhanced photoactivity and better charge separation. The optimum photocurrent density and hydrogen generation rate has been found to be 3.4 mA cm−2 and 127.5 μmole cm−2 h−1 in 1 M Na2SO4 electrolyte solution under 1.5 AM solar irradiance of white light with illumination intensity of 100 mW cm−2.

Here, we report extraordinary field emission properties from one pot synthesized aligned carbon nanotubes endowed with related Fe nanoparticles (NPs). The CNT configuration is in the form of a carbon hollow cylinder (CHC) with CNTs radially aligned towards the CHC axis. The structure generates electron field emission properties such as an ultralow turn on field (0.35 V μm−1 at 10 μA cm−2), a low threshold field (0.41 V μm−1 at 100 μA cm−2) and a high field emission current density (7.71 mA cm−2 at 0.78 V μm−1). It also exhibits multi-fold improvement in the field enhancement factor (1.34 × 104) with highly stable current emission at 100 μA measured for 14 h. No post synthesis treatment is required for enhanced field emission characteristics. The growth related Fe NPs assist in lowering the work function and hence enhancing the field emission properties. The possibility of assembling nano-structured field emitters into macroscale architectures suggests new prospects for next generation three dimensional electron sources.

The report describes the effect of TiO2 nano particles on the hydrogenation characteristics of promising Li-Mg-N-H hydrogen storage system. The effect of different particle size of TiO2 (200, 25 and 7 nm) on de/re-hydrogenation characteristics of Mg(NH2)2/LiH mixture has been investigated. Desorption kinetics of Li-Mg-N-H system with 25 nm TiO2 gets enhanced upto ∼25% as compared to the pristine material kinetics at 453 K (180 °C). The report also deals mechanistic approach for hydrogen release from Li-Mg-N-H system in the presence of TiO2 nanoparticles through XPS analysis of catalyzed sample at various stages of reaction. The XPS analysis confirms that during dehydrogenation nitrogen atom present in Li-Mg-N-H system share their lone pair electrons to Ti (present in TiO2) and provides an alternate decomposition path which has lower activation energy for dehydrogenation.

In the present work, $$\hbox {Al}_{65}\hbox {Cu}_{20}\hbox {Fe}_{15}$$ alloy has been synthesized by melting of pure elements (e.g., Al (99.96%), Cu (99.99%) and Fe (99.98%)), using a radiofrequency induction melting furnace. The as-prepared alloy was subjected to rapid solidification by melt spinning technique at $$\sim $$ 3500 rpm speed on a copper disk of diameter 14 cm. As a result of the melt spinning, nearly 2 mm wide, $$30{-}40\,{\upmu }\hbox {m}$$ thick and 4–5 cm long ribbons were formed. The structural and microstructural characterizations were carried out by X-ray diffraction and transmission electron microscopy techniques. We have performed leaching operation using 10 mol NaOH aqueous solution on the surface using a pipette. Leaching was performed for various durations ranging from 30 min to 8 h. After leaching, the reflectivity reduces and the surface looks reddish brown. The microstructure of the 8 h leached sample shows a breakdown of the quasicrystalline phase but with the evolution of other metallic phases. Copper (Cu) particles are found to be present on the surface of quasicrystal after 4 h of leaching and relatively more iron (Fe) evolves during further leaching of 8 h. This low-cost method to prepare a distribution of nano-Cu/Fe metal particles encourages their uses in catalytic reactions, indicating the possibility of use of quasicrystals as the industrial catalysts.

The present study deals with the structural and microstructural changes with respect to the quenching rate and their correlation with mechanical behavior of melt-spun Ce75Al21Ga4 glassy alloys. The ribbons of the alloy have been synthesized at different quenching rates obtained through different wheel speeds (44, 36, 29, 22 and 15 m/s). The glass forming indicators and mechanical properties have been investigated at different quenching rates. The higher quenching rate obtained through high wheel speed (44, 36 and 29 m/s) has led to phase separation giving rise to nano-amorphous domains in a glassy matrix while the lower quenching rate obtained through lower wheel speed (22 and 15 m/s) produces nano-crystalline grains with size ranges from 25 ± 1 to 120 ± 1 nm. It has been found that the size of the nano-amorphous domains decreases with decrease in wheel speed. The mechanical behavior has been studied using micro-indentation technique. The indentation test indicates that with the same chemical composition, the ribbons synthesized at slow quenching rate exhibits higher hardness and yield strength than those synthesized at faster quenching rate. The ribbons synthesized at 44 m/s contains the large free volume and has the highest shear band density.

The dielectric behavior and alternating current conduction mechanism of nanocrystalline (Co,Ni)Al 2 O 4 aluminate spinel have been investigated over a broad frequency range (1 kHz to 1 MHz) for different temperatures i.e. 50 °C to 90 °C. The low cost and environmental friendly method has been used to developed the nanocrystalline (Co,Ni)Al 2 O 4 spinel phase. The formation of homogeneous single phase of nanocrystalline (Co,Ni)Al 2 O 4 spinel has been confirmed by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. The dielectric response and alternating current conductivity have been observed by inductance, capacitance and resistance bridge which confirms traditional dielectric behavior of (Co,Ni)Al 2 O 4 . The frequency dependent complex dielectric impedance behavior has also been explored. The activation energy of (Co,Ni)Al 2 O 4 has been found nearly 0.3–0.1 eV b/w the frequency range 1 kHz to 1 MHz. The alternating current conduction mechanism reveals the signature of correlated barrier hopping by following the power law where the maximum barrier length has been found 144 ± 0.25 MeV. This alternating current conduction also follows the Meyer-Neldel rule in the low frequency region.

The present study reports the curious catalytic action of a new class of catalyst, quasicrystal of Al65Cu20Fe15 on de/rehydrogenation properties of magnesium hydride (MgH2). Catalyzed through this catalyst, the onset desorption temperature of MgH2 gets reduced significantly from ∼345 °C (for ball-milled MgH2) to ∼215 °C. A more dramatic effect of the above catalyst has been observed on rehydrogenation. Here, 6.00 wt % of hydrogen storage capacity is observed in just 30 s at 250 °C. Improved rehydrogenation kinetics has been found even at lower temperatures of 200 and 150 °C by absorbing ∼5.50 and ∼5.40 wt % of H2, respectively, within 1 min and ∼5.00 wt % at 100 °C in 30 min. These are some of the lowest desorption temperatures and rehydrogenation kinetics obtained for MgH2 through any other known catalyst. The storage capacity of MgH2 catalyzed with the leached version of Al65Cu20Fe15 quasicrystalline alloy degrades negligibly even after 51 cycles of de/rehydrogenation. The feasible reason for catalytic ...

In the present investigation, the chemical leaching of the poly-grain Al65Cu15Co20 and Al65Cu20Co15 decagonal quasicrystalline alloys have been studied. The polished surfaces of as-cast Al65Cu15Co20 and Al65Cu20Co15 alloys have been leached by 10 mol/litre (mol/L) concentrated NaOH alkaline solutions. The X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy techniques have been used for the structural and microstructural characterization of the samples and the chemical composition were characterized using Energy-dispersive X-ray spectroscopy. Chemical leaching exclusively removes the Al from the surfaces of the Al65Cu15Co20 and Al65Cu20Co15 decagonal quasicrystalline alloys, consequentially the formation of porous structure containing nano size particles of Cu, Co and Co3O4 have been observed on the leached surface. The leached surface of Al65Cu15Co20was more porous compared to Al65Cu20Co15 alloy, however the size of the precipitated nano-particles i.e. Cu, Co and Co3O4 were smaller in the case of Al65Cu20Co15 alloy. The elemental mapping through energy dispersive X-ray spectroscopy suggests that the distribution of Cu and Co were formed on the leached surface, however in some regions the oxygen was also detected.

The present report deals with the synthesis of Gd and Co doped BiFeO3 (BFO) i.e. Bi1-xGdxFe1-yCoyO3 (BGFCO, x = 0.0, 0.1; y = 0, 0.05, 0.10, 0.20, 0.25) nanoparticles by sol–gel method. The co-doping leads to band gap engineering of BiFeO3 with the band gap varying from 2.23 eV to 1.77 eV. The band gap engineering coupled with UV–Vis spectroscopy has been used to find the optimum material. The significant lowering in the band gap of the doped BFO is attributed to the deformation produced in Fe–O octahedron geometry as well as rearrangement in its molecular orbitals. The band gap engineering leads to materials with improved solar spectral response which in turn results in better harvesting of solar energy. X-ray diffraction (XRD) patterns indicate the formation of pure phase of BiFeO3 and its doped variants. The surface morphologies and particle sizes of different compositions have been investigated through scanning electron microscope (SEM). The as synthesized BFO as well as its doped variants have been used as photoanodes for hydrogen production through photoelectrochemical (PEC) splitting of water. The optimum material Bi0.9Gd0.1Fe0.75Co0.25O3 (BGFCO-25) with band gap of 1.77 eV has been used as photoanode having PEC configuration of 1 mol/L NaOH as the electrolyte solution and the Pt as cathode using 1.5 AM UV–Vis illumination. This has produced the photocurrent density of 2.03 mA/cm2 and hydrogen production rate of 74.57 μmol cm−2 h−1. The maximum photo-conversion efficiency has been found to be 2.29% for BGFCO-25 which is higher than that of BFO in which it is 0.76%. This noteworthy enhancement in the photoelectrochemical properties is ascribed to narrowing of the band gap which improves the solar spectral response and allows the absorption of higher density of photons. The stability test of the photoanode has been done through chronoamperometry technique.

A simple and fast, one-step, cost effective protocol for silver nanoparticle (AgNP) synthesis has been reported. AgNO3 is reduced using black cardamom (B.C.) extract to produce nanoparticles. Variable size nanoparticles were obtained by choosing the different composition of a reaction mixture comprised of AgNO3 solution and B.C. extract. Nanoparticle formation was monitored by the color change of reaction mixture as well as by UV-Visible spectroscopy. AgNPs has been characterized thoroughly by XRD and TEM analysis for shape and size. A plausible mechanism for reduction of Ag+ has been proposed based on oxidation products of 1,8-cineole, which is one of the major components of B.C. extract. A very important application of these AgNPs has also been shown by preparing AgNP-gelatin composite to check its activity against different strains of bacteria. The results suggest excellent antibacterial activities of the above-mentioned composite films, which can be further developed as antibacterial films for different purposes.

The present investigation describes the hydrogen storage properties of MgH2 ball milled with different additives i.e. graphene templated rare earth metal (La and Ce) fluorides, CeF4 and LaF3. MgH2 ball milled with graphene templated CeF4 (MgH2:CeF4@Gr) has onset desorption temperature of 245 °C, which is 50 °C, 52 °C and 75 °C lower than MgH2 ball milled with LaF3 templated graphene, CeF4 and LaF3 respectively. CeF4@Gr also shows the superior effect amongst all additives during rehydrogenation where MgH2:CeF4@Gr absorbs 5.50 wt% within 2.50 min at 300 °C under 15 atm H2 pressure. Dual tuning effect, i.e. lowering of thermodynamic (62.77 kJ/mol H2: lower from 74 kJ/mol for pristine MgH2) and kinetics barrier (93.01 kJ/mol) has been observed for MgH2:CeF4@Gr. Additionally, MgH2 ball milled with CeF4@Gr shows good reversibility up to 24 cycles of de/rehydrogenation. The feasible working mechanism of CeF4@Gr as additive for MgH2 has been studied in detail with the help of Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction characterizations (XRD).

A simple leaching method was developed to synthesize Cu nanocubes having edge length in the range of 50–80 nm on a quasicrystalline surface. The Al 65 Cu 20 Fe 15 (at%) quasicrystalline ribbons (∼2 mm wide, ∼5 cm long and ∼20 μm thick) have been synthesized by melt spinning techniques. The copper nanocubes were formed by leaching these quasicrystalline ribbons with a 5 M aqueous solution of NaOH. Leaching was performed at various times ranging from 1 to 8 hours (h). The samples were characterized using x-ray diffraction, scanning and transmission electron microscopy as well as energy-dispersive x-ray spectroscopy which confirm the presence of copper nanocubes on the surface of quasicrystal after 8 h of leaching.

Transition metal oxides and sulfides have great potential for energy storage devices due to their large theoretical energy storage capacities. A facile technique was used for the synthesis of nanostructured and phase pure cobalt oxide (Co 3 O 4 ) and subsequently converting it to cobalt sulfide (Co 9 S 8 ). The effect of sulfurization on energy storage capacity of the cobalt oxide was explored. Microstructural characterizations using X-ray diffraction and scanning electron microscopic reveal formation of phase pure and nanostructured Co 3 O 4 and Co 9 S 8 . It was observed that the areal capacitance of Co 3 O 4 (983 mF/cm 2 ) improved significantly after converting to Co 9 S 8 (7358 mF/cm 2 ). The CV curves of the Co 9 S 8 electrode on bending showed outstanding stability with no change in energy storage properties. New insights into the better performance of Co 9 S 8 over Co 3 O 4 based on electrochemical investigations are presented. The performance of the Co 9 S 8 as an electrode material for energy storage applications was further investigated by fabricating a supercapacitor device. The supercapacitor device showed outstanding stability up to 5000 cycles of charge-discharge study. The performance of the supercapacitor was observed to be improving with temperature. The supercapacitor displayed ~100% enhancement in energy storage property on increasing temperature from 10 to 70 °C. Our results suggest that hydrothermally grown Co 9 S 8 on nickel foam can be utilized for high capacity, flexible and binder free electrode for energy storage applications.

In this article, we proposed a facile one-step synthesis of Fe3O4 nanoparticles of different shapes and sizes by co-precipitation of FeCl2 with piperidine. A careful investigation of TEM micrographs shows that the shape and size of nanoparticles can be tuned by varying the molarity of piperidine. XRD patterns match the standard phase of the spinal structure of Fe3O4 which confirms the formation of Fe3O4 nanoparticles. Transmission electron microscopy reveals that molar concentration of FeCl2 solution plays a significant role in determining the shape and size of Fe3O4 nanoparticles. Changes in the shape and sizes of Fe3O4 nanoparticles which are influenced by the molar concentration of FeCl2 can easily be explained with the help of surface free energy minimization principle. Further, to study the magnetic behavior of synthesized Fe3O4 nanoparticles, magnetization vs. magnetic field (M-H) and magnetization vs. temperature (M-T) measurements were carried out by using Physical Property Measurement System (PPMS). These results show systematic changes in various magnetic parameters like remanent magnetization (Mr), saturation magnetization (Ms), coercivity (Hc), and blocking temperature (T B) with shapes and sizes of Fe3O4. These variations of magnetic properties of different shaped Fe3O4 nanoparticles can be explained with surface effect and finite size effect.

Photoelectrochemical splitting of water for chemical fuel production utilizing solar energy is regarded as an effective strategy to resolve crisis of energy. Self assembled and highly ordered titanium dioxide nanotube arrays offers considerable interest for hydrogen generation, since ordered structural design of titania nanotubes provides a unidirectional charge transfer channel for electron's transport. Here, we report the hydrogen generation by self assembled and vertically oriented carbon doped titania nanotube array. Carbon doped titania nanotube array photoelectrodes were synthesized by electrochemical method through the anodization of Titanium (Ti) foil in ethylene glycol bath consisting of 0.3 wt.% NH4F and 2 vol.% water by varying the anodization potential and time. The increase in length of carbon doped titania nanotube array increases the efficiency of photo conversion. However very higher lengths of carbon doped titania nanotube array results into decrease in the efficiency mainly due to recombination of charge carriers. The photocurrent density and hydrogen generation rate was found to be 4.0 mAcm−2 and 150 μmol cm−2 h−1 for carbon doped titania nanotube array of lengths 13.5 μm in 1 M NaOH electrolyte solution under 1.5AM solar irradiance of white light with illumination intensity of 100 mWcm−2.

We report the potential destabilizing effects of graphene nanofibers on the hydrogen release property of hydrazine borane via state-of-the-art ab initio calculations for the first time. Interaction ...

The present investigation describes the synergistic role of Li4(BH4)(NH2)3 and ZrFe2 in the hydrogen storage behaviour of a Li–Mg–N–H hydride system. The onset desorption temperature of ZrFe2-catalysed Mg(NH2)2–LiH–Li4(BH4)(NH2)3 is ∼122 °C, which is 83 °C, 63 °C, and 28 °C lower than that of thermally treated 2LiNH2–1MgH2, 2LiNH2–1MgH2–4 wt%ZrFe2, and 2LiNH2–1MgH2–0.1LiBH4 composites, respectively. Native Mg(NH2)2–LiH–Li4(BH4)(NH2)3 absorbed only 2.78 wt% of H2 within 30 min. On the other hand, the ZrFe2-catalysed Mg(NH2)2–LiH–Li4(BH4)(NH2)3 sample absorbed 3.70 wt% of hydrogen within 30 min and 5 wt% of H2 in 6 h at 180 °C and 7 MPa H2 pressure. Mg(NH2)2–LiH–Li4(BH4)(NH2)3 catalyzed with ZrFe2 shows negligible degradation of the storage capacity even after repeated cycles of de/rehydrogenation. The effect of ZrFe2 and Li4(BH4)(NH2)3 on a Mg(NH2)2/LiH composite has been described and discussed with the help of structural (X-ray diffraction), microstructural (electron microscopy), and vibrational modes of molecules through FTIR studies. The present results suggest that an optimum catalysis may originate from the synergistic action of an in situ formed quaternary hydride (Li4(BH4)(NH2)3) and an intermetallic-like ZrFe2, which acts as a pulverizer cum catalyst.

With the combination of experiment and first-principles theory, we have evaluated and explored the catalytic effects of graphitic nanofibres for hydrogen desorption behaviour in magnesium hydride. Helical form of graphene nanofibres (HGNF) have larger surface area, curved configuration and high density of graphene layers resulting in large quantity of exposed carbon sheet edges. Therefore they are found to considerably improve hydrogen desorption from MgH2 at lower temperatures compared to graphene (onset desorption temperature of MgH2 catalyzed by HGNF is 45 °C lower as compared to MgH2 catalyzed by graphene). Using density functional theory, we find that graphene sheet edges, both the zigzag and armchair type, can weaken Mg H bonds in magnesium hydride. When the MgH2 is catalyzed with higher electronegative and reactive graphene edge of graphene, the electron transfer occurs from Mg to carbon, due to which MgH2 is dissociated into hydrogen and Mg H component. The Mg gets bonded with the graphene edge carbon atoms in the form of C Mg H and C H bonds. In the as formed C Mg H, the graphene edges “grab” more electronic charge as compared to the normal charge donation of Mg to H. This leads to the weakening of the Mg H bond, causing hydrogen to desorbs at lower temperatures.

Visceral leishmaniasis (VL) is a life-threatening parasitic disease affecting impoverished people of the developing world; and much effort has been spent on the early case detection and treatment. However, current diagnostics and treatment options are not sufficient for appropriate surveillance in VL elimination setting. Hence, there is a dire need to develop highly sensitive diagnostics and less toxic effective treatments for proper management of cases and to achieve the sustained disease elimination. Although, promising results have been observed with nanomedicines in leishmaniasis; there are great challenges ahead especially in translating this to clinical setting. This review provides updated progress of nanomedicines in VL, and discussed how these innovations and future directions play vital role in achieving VL elimination.

β-Amylase was immobilized onto GQDs using 3-aminopropyltriethoxysilane and glutaraldehyde. Optimization was carried out by Box-Behnken design and binding was confirmed by SEM, AFM, FTIR and fluorescence microscopy. Predicted optimum immobilization efficiency (88.64%) was very close to actual (87.98%), which confirmed the success of the immobilization process. The immobilized enzyme showed maximum activity at pH 5.0 and 57 °C, whereas Km and Vmax were found to be 6.40 mg/mL and 714.28 μmol/min/mg, respectively. The enzyme retained 75% activity after 12 uses at 30 °C. Increased values of ΔG° ΔH°, half-life and activation energy of the enzyme inactivation (ΔEd) revealed that thermo-stability increases after immobilization and the process followed first-order kinetics (r2 > 0.96). The activation energy of catalysis (ΔEa) and ΔEd for immobilized enzyme were 22.58 and 158.99 ± 1.10 kJ/mol, respectively which revealed that denaturation of the enzyme requires a higher amount of energy rather than catalysis. Thermodynamic and fluorescence spectroscopic studies revealed that the process is non-spontaneous (ΔG > 0) and endothermic (ΔH > 0) and occurred through protein unfolding rather than aggregation (ΔS > 0). Thus increase in thermo-stability of immobilized fenugreek β-amylase and non-toxic nature of GQDs could be exploited for maltose production in beverage, food and pharmaceutical industries.

High-quality graphene is highly enviable material due to its seminal role amongst several areas in modern technology including its role as nanocarrier for site selective drug grafting and delivery applications. Here, we report a facile, cost-effective and single-step method to produce high-quality graphene through customised electrochemical exfoliation of graphite anode in alkaline electrolyte medium. The quality of graphene sheets (GS) were investigated by Raman, TEM/HRTEM, AFM, and FTIR techniques. The high quality as well as excellent Π-Π stacking nature of the honeycomb lattice of graphene was confirmed by measuring the quenching capability through photo-luminescence spectroscopy using organic dyes. A plausible mechanism for the graphite exfoliation has been given where evolution of high density of oxygen molecules exerts large force on the graphitic layers leads to exfoliation and consequent synthesis of graphene. Furthermore, to explore the application of the graphene sheets so synthesized, we carried out studies which may make them as suitable carriers for drug delivery. For this, graphene sheets were functionalized with L-cysteine and attached with the drugs Amphotericin-B (AmB) and Tamoxifen citrate (TMX). The conjugation of drugs with L-cysteine functionalized graphene has been confirmed through FTIR and Raman spectroscopic techniques. The drug loading efficiency of FGS for AmB and TMX was 75.00% and 94.31%, respectively. The present formulation of drugs (AmB and TMX) conjugated with graphene is suitable for the targeted drug delivery as it will enhance the efficacy and reduce cytotoxicity associated with drug.

Leishmaniasis is a syndrome caused by the protozoan parasites which is transmitted by the bite of the female sand fly. The disease has three major forms: Cutaneous, Mucocutaneous and most fatal Visceral Leishmaniasis (VL) in affected individuals. Additionally, some of the VL patients (

The present study reports on the structural and magnetic phase transitions in Pr-doped polycrystalline Tb0.6Pr0.4MnO3, using high-resolution neutron powder diffraction (NPD) collected at SINQ spallation source, to emphasize the suppression of the sinusoidal magnetic structure of pure TbMnO3 and the evolution to a collinear A-type antiferromagnetic ordering. The phase purity, Jahn–Teller distortion, and one-electron bandwidth for eg orbital of Mn3+ cation have been calculated for polycrystalline Tb0.6Pr0.4MnO3, in comparison to the parent materials TbMnO3 and PrMnO3, through the Rietveld refinement study from x-ray diffraction data at room temperature, which reveals the GdFeO3 type orthorhombic structure of Tb0.6Pr0.4MnO3 having Pnma space group symmetry. The temperature-dependent zero field-cooled and field-cooled dc magnetization study at low temperature down to 5 K reveals a variation in the magnetic phase transition due to the effect of Pr3+ substitution at the Tb3+ site, which gives the signature of the antiferromagnetic nature of the sample, with a weak ferromagnetic component at low temperature-induced by an external magnetic field. The field-dependent magnetization study at low temperatures gives the weak coercivity having the order of 2 kOe, which is expected due to the canted-spin arrangement or ferromagnetic nature of Terbium ordering. The NPD data for Tb0.6Pr0.4MnO3 confirms that the nuclear structure of the synthesized sample maintains its orthorhombic symmetry down to 1.5 K. Also, the magnetic structures have been solved at 50 K, 25 K, and 1.5 K through the NPD study, which shows an A-type antiferromagnetic spin arrangement having the magnetic space group Pn′ma′.

This paper discusses the electrochemical energy storage and room temperature hydrogen, methane and carbon dioxide adsorption/desorption behaviour of commercial nanoporous activated carbon having a specific BET surface area 1007 m2 g−1 and pore volume 0.371 cm3 g−1. The electrochemical energy storage behaviour of activated carbon was determined from its capacitive performance using standard three and two-electrode cells. The specific capacitance (CS) of the sample determined using a three-electrode cell is 138 F g−1 at 0.1 A g−1 with the capacitance loss of 1% after 2000 charge/discharge cycles. Whereas, CS determined using a two-electrode cell is 98.8 F g−1 at 0.2 A g−1 with the capacitance loss of 3% after 5000 charge/discharge cycles. The energy and power densities of two-electrode cell supercapacitor is 19.76 Wh kg−1 and 3.77 kW kg−1, respectively. The sample exhibits gaseous uptake capacities of 0.23 wt% H2, 8.52 wt% CH4 and 37.25 wt% CO2 at ~50 atm/293 K.

In the present study, the cations Co 2+ /Ni 2+ and Al 3+ distribution in nanocrystalline (Co, Ni)Al 2 O 4 spinel have been investigated using X-ray and transmission electron microscopy. The nanocrystalline (Co, Ni)Al 2 O 4 spinel has been synthesized using mechanically activated Al 70 Co 15 Ni 15 quasicrystalline precursor through annealing at 600 °C in controlled oxygen atmosphere. The mechanical activation of single phasic decagonal Al 70 Co 15 Ni 15 quasicrystal was carried out in a high energy attritor ball mill for 40 h with 40:1 ball to powder ratio using toluene as a process control agent. The high resolution x-ray diffraction data has been refined by the Rietveld method using JANA2006 and subsequently, the corresponding structure has been constructed using Diamond4.0. The structure was also confirmed by analysis of transmission electron microscopy linearized diffraction pattern profile of d -values and corresponding plane. These analyses indicate that the cations Co 2+ and Ni 2+ distributed in the tetrahedral coordinated sites are the dominant species in the normal spinel phase.