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 e(g) 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 '.

In the present investigation the glass forming ability of Ce65Al25Co10 metallic glass has been reported. It was successfully synthesised using melt spinning techniques. The existence of amorphous phase in Ce65Al25Co10 alloy have been proved using X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. The thermal analysis of the synthesised sample using differential scanning calorimetry (DSC) shows a glass transition around 371 K, thus confirms existence of glassy phase at room temperature. The hardness of the synthesised sample at different load have been demonstrated. Moreover, the yield strength of the synthesised sample has also been calculated by means of hardness data and Meyer exponent.

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 m(2) g(-1) and pore volume 0.371 cm(3) 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 (C-S) 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% H-2, 8.52 wt% CH4 and 37.25 wt% CO2 at similar to 50 atm/293 K.

The present investigation reports the synthesis of Carbon Aerogel (CA) with varying pore size and surface area by changing the initial precursor that is, Resorcinol (R) and novel Catalyst (triethyl amine [TEA]) (C) ratio (R/C). The catalyst, TEA allows the gel to dry with negligible shrinkage. The R/C ratio has been kept 1000, 2000 and 3000. The CA with R/C = 1000 has the lowest pore size 1.93 nm, the highest surface area (369.14 m(2)/g) and the highest CO2 uptake of 24.40 wt.% (5.54 mmol/) at 40 atm CO2 pressure. The activated version of optimum CA (R/C = 1000) has been found to have an average pore diameter similar to 1.91 nm and CO2 uptake capacity of 29.56 wt% (6.71 mmol/g) at 25 degrees C which is one of the highest CO2 storage capacity of CAs reported so far. Thus, the present manuscript put forward highly efficient and tunable CAs for enhanced CO2 storage.

Heusler alloys possess the structure of an ordered compound while displaying most of the properties of metals. Numerous magnetic exchange mechanisms may be operating in such systems. Herein, the structural and magnetic properties have been investigated as a function of substitution of Al by Ga in Fe50Mn25Al25-xGax (x = 0, 2.5, 5.0, 7.5, 10.0) quaternary (pseudo-ternary) full Heusler alloys. The X-ray diffraction analysis confirms the substituting Al by Ga promoting the lattice expansion in the L2(1) crystal structure in Fe50Mn25Al25-xGax alloys. The line scanning profile using energy dispersive X-ray analysis investigations suggests the homogeneous distribution of Ga in all the alloys. The magnetic moment of the alloys was found to be affected by Ga as the antiferromagnetic counterpart increases with Ga. A decrease in the value of Curie temperature was found with increase in Ga content. A second-order magnetic phase transition was observed in the alloys above room temperature. (C) 2020 Elsevier B.V. All rights reserved.

Schematic diagram of the de/rehydrogenation of MgH2–(MgF2 + SrH2)@Gr.

The present study features Bi1-xSmxFeO3 (BSFO) nanoparticles anchored on high-quality, reduced graphene oxide (RGO) sheets via a two-step ultrasonication method for photo electrochemical (PEC) studies relating to solar hydrogen generation. Sm doping leads to the formation of pure BFO type phase without any secondary phases. The structural, morphological, optical, and local structure analyses of BSFO and BSFO@RGO have been done through X-ray diffraction, scanning electron microscope, UV-Vis spectrophotometer, and Raman spectrometer, respectively. The BSFO nanoparticles have been templated on reduced graphene oxide. The BSFO@RGO has been employed as a photoanode for PEC measurements under the simulated solar irradiation of intensity 100 mW-cm(-1). The optimum photoanode has been found with Bi0.95S0.05FO3@RGO. The highest photocurrent density and solar to hydrogen (STH) conversion efficiency have been found as 2.40 mA/cm(2) (at 0.5 V vs. saturated calomel electrode) and 2.45%, respectively. Furthermore, the stability of the photoanode against photo corrosion has also been tested by the chronoamperometric technique. During 2 h experiment, the average photocurrent density has been maintained at 1.5 mA/cm(2) (at 0 V vs. SCE). The improved photocatalytic activity of BSFO@RGO has been explained based on the effect of doping, better solar spectral response, hindering the recombination loss of photo-generated charge carriers, and fast, facile charge transport. Although earlier studies have used Bi(Sm)FeO3 photoanode, hydrogen production has been observed for the first time in the present investigation to the best of our knowledge. Also, it appears that hydrogen production at zero external bias as observed in the present study suggests a new feature for bandgap tailored BFO. (C) 2021 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

The present investigation reports the dielectric phase transition studies in polycrystalline Gd0.55Ca0.45MnO3 along with ac conduction and structural property. Polycrystalline Gd0.55Ca0.45MnO3 has been synthesized by the solid-state synthesis route at 1350 degrees C which crystallized in the orthorhombic phase with centrosymmetric Pnma symmetry at room temperature. The complex dielectric and modulus properties of polycrystalline Gd0.55Ca0.45MnO3 has been explored in the frequency range of 500 Hz to 1 MHz at low temperatures having the range 6 K-200 K. The real part of dielectric permittivity shows the sharp increase up to 30 K-120 K temperature range and then decreases constantly which confirm the characteristic of relaxor ferroelectric material. The low-temperature dielectric study reveals that Gd0.55Ca0.45MnO3 possesses a high dielectric permittivity and low loss below 120 K. The frequency variation of ac conductivity shows the correlated barrier hopping in the temperature range of 10 K-60 K and 100 K-180 K and gives the signature of small polaron hopping at 60 K-100 K. Thermal variation of activation energy for Gd0.55Ca0.45MnO3 gives the activation energy of 0.0634(2) eV for higher frequency 1 MHz.

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.

Atomically thin metallic alloys are receiving increased attention due to their prospective applications as interconnects/contacts in two-dimensional (2D) circuits, sensors, and catalysts, among others. In this work, we demonstrate an easily scalable technique for the synthesis of 2D metallic alloys from their 3D quasicrystalline precursors. We have used aluminum (Al)-based single-phase decagonal quasicrystal Al66Co17Cu17 alloy to extract the corresponding 2D alloy structure. The 2D layered Al alloy possesses 2-fold decagonal quasicrystalline symmetry and consists of two- or three-layer-thick sheets with a lateral dimension of microns. These 2D metallic layers were combined with the atomic layers of tungsten disulfide to form the stacked heterostructures, which is demonstrated to be a stable and efficient catalyst for hydrogen evolution reaction.

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.

To explore the practical feasibility of exotic carbon, various types of geometries of CNT configurations have been investigated such as CNT film, vertically aligned nanotubes, 3D pillared graphene-CNT network etc. High-performance and applicability of CNT derived electrodes in electrochemical energy storage depend on the structural design and high aspect ratio geometry. Here, we have strategically designed electrode derived from a special type of 3D geometry known as carbon hollow cylinders (CHCs) made up of CNTs arranged in the radial direction. The exceptional geometry provides a high areal capacity of 513.92 C/cm(2) at an applied current density of 16 mA/cm(2). Also, high specific energy of 41.13 mWh/cm(2) at the specific power of 5694.92 mW/cm(2) originated from supercapacitors and battery response of the electrode material was attained, which idealized the fundamental of theory of composite type electrode material. Hence, proposed geometry sets a stepping stone for a paradigm shift in lightweight electrode which is not only binder-free but also designed with a special geometry that provides an exceptional higher areal capacity with stable network. (C) 2020 Elsevier Ltd. All rights reserved.

The present investigation reports the formation and stability of multi-component AB2-type Laves phase in Ti–Zr–Ni (V, Cr, Fe, Mn, Co)ternary to octonary alloys system. To probe the formation and stability of AB2-type Laves phase in high-entropy alloys, a series of multi-component alloys have been synthesized via melting under protective Ar atmosphere and subsequent annealing at 525 K for 40 h. Systematic investigation has been carried out to understand phase stability using both thermodynamic and parametric approaches. X-ray diffraction measurement and Rietveld analysis indicate the formation of C14 Laves phase in multi-component alloys. The enthalpy of mixing (ΔHmix), size difference (δ) and valence electron concentrations (VEC) have been found to play stellar role in controlling the formation of multi-component Laves phase in these alloys. The valence electron concentrations and electrons per atom ratio (e/a) dictate the choice of elements for the stabilization of Laves phase in these high-entropy alloys.

The increasing plead for the realization of ultra-fast, miniaturized, compact, and ultra-low power consumption in electronic as well as spintronic devices has propelled the quest for novel multiferroic materials that efficiently enable voltage control of magnetism. The present work reports the phase stability, magnetic and dielectric responses of polycrystalline Bi1−xLaxFe1−yNiyO3 (0 ≤ x ≥ 0.2 and 0 ≤ y ≥ 0.2) multiferroic ceramics synthesized through a simplistic sol–gel approach. The maneuver substitutions of La at A− site of BiFeO3 multiferroic eliminate the secondary phases formed owing to impurities. Rietveld refined XRD analysis reveals the structural transformation of the orthorhombic (Pbnm) phase as La substitution increases. However, an additional lattice distortion is induced as a result of the substitutions of Ni atoms at B− site. A substantial enhancement in magnetic and dielectric responses has been found in the co-doped (Ni and La) sample at both A and B− sites as a result of the size confinement of nano-crystallites, the exchange interaction between Fe3+ and Ni2+ ions, and corresponding variation in Fe–O–Fe bond angles. The dielectric constant has increased substantially in the low-frequency region with simultaneous substitutions of La and Ni at the sites of Bi and Fe, respectively. A careful observation of temperature-dependent magnetization curves (FC and ZFC) indicates a spin glass response with entangled ferromagnetic components. The experimental findings infer that the co-substitutions of La and Ni at their respective sites in Bi1−xLaxFe1−yNiyO3 (0 ≤ x ≥ 0.2 and 0 ≤ y ≥ 0.2) may significantly improve the ferromagnetic and dielectric responses of the studied nanoceramics.

In present investigation, the selective removal of Al from the quasi-lattice sites of quasicrystalline alloy surface was examined in order to produce the nano-particles of metal/metal oxides within the microporous network. Al was selectively etched from both the as-cast as well as annealed Al63Cu25Fe12 quasicrystalline alloys through the treatment with 10 mol NaOH solution at different time interval. In the as-cast sample, higher density of porosity was observed compared to that of annealed alloy. However, dealloying specifically for 4 and 8 h yielded nano-size particles on quasicrystalline surface (of both the alloys) in which very fine particles were detected at 8 h. The increase in density and decrease in size of the nano-particles was found with dealloying duration. X-ray diffraction analysis was performed to characterize the samples. Scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis were carried out to investigate the surface microstructure, internal morphology and chemical composition. The chemical dealloying treatments yielded nano-particles of Cu and Fe along with their oxides on the quasicrystalline surface. Furthermore, the catalytic activity of leached quasicrystalline materials was evaluated towards degradation of non-biodegradable and hazardous methylene blue (organic dye). (c) 2020 Elsevier B.V. All rights reserved.

Atomically thin metallic alloys are receiving increased attention due to their prospective applications as interconnects/contacts in two-dimensional (2D) circuits, sensors, and catalysts, among others. In this work, we demonstrate an easily scalable technique for the synthesis of 2D metallic alloys from their 3D quasicrystalline precursors. We have used aluminum (Al)-based single-phase decagonal quasicrystal Al66Co17Cu17 alloy to extract the corresponding 2D alloy structure. The 2D layered Al alloy possesses 2-fold decagonal quasicrystalline symmetry and consists of two- or three-layer-thick sheets with a lateral dimension of microns. These 2D metallic layers were combined with the atomic layers of tungsten disulfide to form the stacked heterostructures, which is demonstrated to be a stable and efficient catalyst for hydrogen evolution reaction.

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 similar to 204 degrees C, which is 31 degrees C and 36 degrees 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@Cr on MgH2 has been put forward. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

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. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

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 (PSI), 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. 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 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 A-type antiferromagnetic spin arrangement.

Carbon, a solid element, is the basis of organic chemistry. It exists in nature in various forms (e.g., coal, diamond, graphite, complex molecules). Scientists have realized that carbon is an extremely versatile material, and this has attracted their attention. The discovery of fullerene has initiated a new era in carbon chemistry. Other exotic forms of carbon nanomaterials are nanotubes, graphene, carbon quantum dots, etc. These nanomaterials have gained attention due to their unique electronic, optical, thermal, mechanical, and chemical properties. They have given scientists and technologists the opportunity to make important advances in fundamental and material science and the expansion of disruptive technologies. Presently, the materials research community continues to explore and exploit new low-dimensional graphitic carbon allotropes at an unparalleled rate. The present chapter is focused on the development of research in the the synthesis of carbon nanomaterials, e.g., CNTs, graphene, fullerene, and quantum dots. It also discusses our R and D efforts towards the synthesis and characterization of these carbon nanomaterials.