• Volume 43, All articles

Continuous Article Publishing mode

• Effect of barium sulphate on mechanical, DMA and thermal behaviour of woven aloevera/flax hybrid composites

The natural fibre-reinforced polymeric composites attract themanufacturing industries due to their recyclability, cost-effectiveness and eco-friendly nature. The natural hybrid reinforced polymeric (HNRP) composite overcomes thelimitations in mechanical properties of the mono-natural fibre-reinforced composites. In this research work, the effect of barium sulphate (BaSO$_4$) on the mechanical characterization of HNRP (aloevera/flax/barium sulphate) composites was examined as per ASTM standard. BaSO$_4$ is preferred as a filler based on the absence of self-motion, high density and high melting point (1580◦C). The thermal stability of the HNRP composite was determined by thermogravimetric analysis (Model: TG/DTA 6200). The water absorption and dynamic mechanical properties of the HNRP composites were estimated.The fractography images were analysed to recognize the fractured surface morphology using a scanning electron microscope. The HNRP5 composite has the maximum tensile strength of 34.72 MPa, predominantly based on the interlocking of the flax fibre and plasticity of the composite improved by the influence of BaSO$_4$. The impact strength decreased noticeably with theaddition of barium sulphate in the composite. The weight reduction of around 7–9% was observed in the temperature range of 100–200$^{\circ}$C. The mono-composites (HNRP1&2) absorbed, respectively, 4.8 and 3.5% of moisture; with the addition of BaSO$_4$, the same combination absorbed 4.2 and 3.2% of water content, which was due to the low water absorption capability of BaSO$_4$. The storage modulus of the HNRP5 composite has maximum magnitude in the glassy region and minimum in the rubber region.

• Green synthesis and structural characterization of gold nanoparticles from Achillea wilhelmsii leaf infusion and in vitro evaluation

The aim of this study is to green-synthesize gold nanoparticles (GNPs) by leaf infusion of Achillea wilhelmsii (AW) and to evaluate their biological effects. The synthesized AW-GNPs were characterized by UV–Vis spectroscopy, Fourier transform infrared, X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic light scattering analyses. The antibacterial and cytotoxicity activities of AW infusion and AW-GNPs were evaluated. Antioxidant activity was evaluated by 1, 1-diphenyl-2-picrylhydrazyl test. Moreover, the electrochemical activity of AW-GNPs as a modifier ata glassy carbon electrode (GCE) was studied. The surface plasmon resonance absorption band at 540nm in the UV–Vis spectrum discloses the reduction of gold cations into GNPs. The XRD pattern of GNPs shows the crystal structure of AW-GNPs, and TEM image displays the spherical shape of GNPs with small size (2.7–38.7 nm). The AWinfusion and AW-GNPs demonstrated a maximum antioxidant activity of 68 and 58%, respectively. AW-GNPs showed antibacterial activity against gram-positive bacteria, without affecting gram-negative bacteria. Also, AW-GNPs exhibited the cytotoxicity effects against MDA-MB-468 cancer cell line, and the electrochemical study indicated a significant electrocatalytic activity of AW-GNPs. The results indicate the advantages of using AW leaf infusion for the production of GNPs with antibacterial, antioxidant, cytotoxic and electrocatalytic activities.

• Pristine and modified-mesoporous alumina: molecular assistance-based drug loading and sustained release activity

The present article reports on the synthesis of mesoporous alumina and its modification through $\beta$-cyclodextrin (BCD) incorporation for loading and release studies of amoxicillin. The drug loading in the mesoporous matrices was found to be activated upon providing molecular assistance by amino acids, L-methionine, L-proline and L-phenylalanine. The effect of molecular assistance has been attributed to intermolecular interactions between the drug and the individual amino acids which have been further confirmed by different spectroscopic studies. The drug-loaded material with BCD modification wasfound to exhibit a sustained release mechanism in physiological pH and is suggested as a proposed material for hip joint prosthesis.

• Synthesis and characterization of Dy-doped Lu$_1$Gd$_2$Ga$_2$Al$_3$O$_{12}$ phosphor for LEDs

The synthesis and characterization of Dy-doped Lu$_1$Gd$_2$Ga$_2$Al$_3$O$_{12}$ are reported in this article. Solid-statereaction method is used to synthesize the material. X-ray diffraction and scanning electron microscopy characterization techniques are used to study the phase and structure of the synthesized material. Luminescence, which is the main propertyof the phosphor material, is characterized by UV- and X-ray-induced luminescence spectroscopy. Lu$_1$Gd$_2$Ga$_2$Al$_3$O$_{12}$:Dy$^{3+}$phosphor shows its highest emission spectra in blue and yellow regions. A combination of yellow and blue gives us white light, displayed by chromaticity diagram for this phosphor. Hence, this phosphor may be used in white-light-emitting diodes. The absorption spectra of our material match well with spectral curve of LEDs. Therefore, it may be used in LEDs applications.

• Temperature-dependence calculation of lattice thermal conductivity and related parameters for the zinc blende and wurtzite structures of InAs nanowires

Theoretical calculations are performed on lattice thermal conductivity (LTC) and related parameters for the zinc blende and wurtzite structure of InAs nanowires (NWs) with diameters of 50, 63, 66, 100 and 148 nm through the Morelli–Callaway model. For the model to be efficiently applicable, the longitudinal and transverse modes are considered. The melting point of the various-sized NWs is considered to estimate the Debye and phonon group velocities. The impacts of Grüneisen parameter, dislocations and surface roughness are also successfully utilized to address the calculated and measured LTC of the semiconductor under investigation. Results show that the Grüneisen parameter increases with decreasing NW diameter and that phonon confinement leads to an observable deviation of the calculated LTC curve from that of the experimental one in the case of bulk InAs. We assume that NW boundaries, dislocations and imperfections are responsible for the scattering of phonons along with electrons and other phonons because of normal and Umklapp processes. Therefore, at a specified temperature, LTC depends on the size and crystal structure of the semiconductor. As such, the thermal and mechanicalparameters of InAs can be greatly modified by decreasing the size and dimension of the semiconductor as a result of the quantum-confinement effect.

• Gold-nanoparticle- and nanostar-loaded paper-based SERS substrates for sensing nanogram-level Picric acid with a portable Raman spectrometer

Nanoparticle (NP)-loaded filter paper (FP)-based surface-enhanced Raman scattering (SERS) substrates have been prepared using differently shaped gold (Au) NPs. The shape of Au NPs plays a significant role in the amplification ofSERS signal. Here, two differently shaped Au NPs were synthesized using two different techniques: (a) femtosecond (fs) laser ablation in liquid and (b) chemical method. Spherical shaped Au NPs were obtained using fs ablation of a bulk Autarget in distilled water and Au nanostars (NSs) were achieved through chemical process utilizing N-vinyl-2-pyrrolidone as a reducing/capping agent. The size and shapes of these synthesized NPs and NSs were investigated meticulously usingdifferent characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy and X-ray diffraction. Both the NPs and NSs were subsequently loaded onto commercially available FP by simple drop casting method. To achieve higher number of hot spots, the aggregated spherical NPs were obtained by addition of NaCl. The non-aggregated spherical, aggregated spherical, and star Au NPs loaded on FP were used for the detection of a dye (Nile blue) and an explosive molecule (Picric acid).

• Comparative analysis on optical and photocatalytic properties of chlorophyll/curumin-sensitized TiO$_2$ nanoparticles for phenol degradation

In this work, natural-dye-sensitized photocatalysts (NDSPs) of TiO$_2$ were prepared by a simple wetness impregnation method, in which natural pigments of chlorophyll and curcumin were initially extracted from fresh parsley leaves andlong roots of dried turmeric, respectively. The as-prepared NDSPs were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and UV–vis diffuse reflectance (DRS) spectroscopy. XRD and SEM studies verified intact structural and morphological properties for NDSPs of TiO$_2$ compared to non-sensitized nanostructures, while FT-IR and DRS analyses confirmed the presence of dye pigments on the surface of TiO$_2$ photocatalysts after the photosensitization process. A red-shift towards longer wavelengths was observed in band-gap energies ofdye-sensitized samples. These NDSPs indicated efficient photocatalytic performances towards decomposing phenol in visible light irradiation. Phenol degradation experiments are systematically conducted to optimize four key operating parameters, including irradiation time, initial pH of the reaction mixture, dye-sensitized TiO$_2$ dosage and initial phenol concentration. Dye-sensitization using chlorophyll pigments results in the highest phenol degradation rate (85%) compared with that of samples sensitized with curcumin pigments (75%), which is perfectly in agreement with the corresponding band-gap energies. Photodegradation processes were modelled by the Langmuir–Hinshelwood kinetics, while the adsorption equilibrium was investigated based on Langmuir and Freundlich isotherms. Lastly, possible mechanisms involved in the process of phenol photodecomposition were proposed.

• Eu(III)-doped barium tellurooxyphosphate phosphor with orange-red emission

Eu$^{3+}$ photoluminescence (PL) is studied in the tellurooxyphosphate, Ba$_2$TeO(PO$_4$)$_2$, host. A series of phosphor compositions with varying concentrations of Eu$^{3+}$ dopant in Ba$_2$TeO(PO$_4$)$_2$ are synthesized by high temperature solid-state reaction and the PL spectra are recorded. Under 395 nm wavelength excitation, the emission spectrum shows a single peak corresponding to the non-degenerate transition, ${}^5$D$_0$ $\to$ ${}^7$F$_0$ indicating that Eu$^{3+}$ preferentially occupies a singlecrystallographic site. The peak due to the degenerate hypersensitive ${}^5$D$_0$ $\to$ ${}^7$F$_2$ electric dipole transition of Eu$^{3+}$ in theemission spectrum indicates that the site occupied by Eu$^{3+}$ in the tellurooxyphosphate host lattice is non-centrosymmetric. The CIE coordinate values are $x = 0.61$ and $y = 0.34$ and are found to be close to the values of the reference phosphor Y$_2$O$_3$:Eu$^{3+}$.

• An improved synthesis of iron phosphate as a precursor to synthesize lithium iron phosphate

Two different kinds of FePO$_4$: amorphous FePO$_4$ and crystalline FePO$_4$, were synthesized as a precursor to synthesize LiFePO$_4$/C. The crystalline FePO$_4$ was obtained by treating amorphous FePO$_4$ with phosphoric acid refluxing. Inductively coupled plasma-atomic emission spectrometry was used to evaluate the impurity content. The obtained materialswere characterized by chemical analysis, scanning electron microscopy and X-ray diffraction. The results showed that the performance of LiFePO$_4$/C synthesized by crystalline FePO$_4$ is significantly better than when LiFePO$_4$/C is synthesized from amorphous FePO$_4$. The capacity retention and capacity fade of LiFePO4/C synthesized from crystalline FePO$_4$ was 70.9% at $−$20$^{\circ}$C and 0.012% per cycle after 150 cycles at 1$C$, respectively. The better performance from using crystalline precursor resulted from a more uniform powder with fewer crystalline defects and impurities.

• Theoretical examination of oxygen reduction reaction (ORR) on carbon nanocone (CNC) for fuel cells

Recently, various studies were performed to propose and discover acceptable catalysts for oxygen reduction reaction (ORR) in various fuel cells. Here, performance of boron-doped carbon nanocone (CNC) as catalyst to ORR via theoretical methods is examined. The ORR paths through ER and LH mechanisms were studied. Results showed that onsetpotentialand over-potential on ORR of boron–CNC were 0.73 and 0.50 V, respectively. The calculated exchange current density and transfer coefficient of B–CNC were $ca.$ $6.5 \times 10^{−6}$ A cm$^{−2}$ and 0.52, respectively. Results demonstrate that boron-doped CNC is a high-potential catalyst to ORR.

• Time-resolved fluorescence decay and Gaussian analysis of P3HT-derived Ho$^{3+}$- and Tm$^{3+}$-doped ZnO nanostructures

The fluorescence vibrational features of as-synthesized P3HT–ZnO:Ho${}^{3+}$ and P3HT–ZnO:Tm${}^{3+} thin films were investigated using Gaussian analysis. Relative to P3HT–ZnO:Tm$^{3+}$film, detailed Gaussian analysis of the fluorescence spectra revealed weaker intensity exhibited in P3HT–ZnO:Ho$^{3+}$film due to better charge transfer. Moreover, we comparatively present the Huang–Rhys factor and relaxation energy of the samples, which are calculated using relations derived from the Franck–Condon theory. Furthermore, P3HT–ZnO:Ho$^{3+}$film exhibits lower relaxation energy as compared with P3HT–ZnO:Tm$^{3+}$film, which implies better conjugation length. Finally, the singlet exciton lifetime of P3HT–ZnO:Ho$^{3+}$samplewas found to be shorter as compared with P3HT–ZnO:Tm$^{3+}$, while the calculated exciton diffusion length was 6.4 and 10.3 nm, respectively. • Titania-based porous nanocomposites for potential environmental applications Titania–zeolite Y composites were synthesized by a facile solid-state dispersion method. The synergistic effects of porous zeolite structure and novel photocatalysis properties of titania nanoparticles were exploited. The physical properties of the composites were characterized by scanning electron microscopy, energy-dispersive X-ray, X-ray diffraction, diffuse reflectance spectroscopy, fourier transform infra-red spectroscopy and photoluminescence spectroscopy. Porosity and surface area of the composites were determined from Brunauer–Emmett–Teller studies. The antibacterial effect and the photocatalysis properties of these composites were studied. Composites exhibited higher growth reduction of Escherichia coli and Staphylococcus aureus as compared with the pure forms ($P$25 titania and zeolite Y). Maximum growth reduction of both types of bacterial cells (gram-positive as well as gram-negative) was observed with 20% titania–zeolite composite. The composite demonstrated 40 and 30% enhancement in the growth reduction of E. coli and S. aureus, respectively, as compared with the pure forms; 10% composite exhibited 50% enhancement in the photocatalysis efficiency of methylene blue dye degradation as compared with$P$25 titania nanoparticles and led to a complete removal of the dye in the first 60 min of photocatalysis process. Mechanisms for both applications have been proposed in light of the observed results. • Synthesis, characterization and anticorrosion behaviour of a novel hydrazide derivative on mild steel in hydrochloric acid medium A novel corrosion inhibitor, namely$N'$-[(4-methyl-1$H$-imidazole-5-yl)methylidene]-2-(naphthalen-2-yloxy) acetohydrazide (IMNH), has been synthesized and characterized by${}^1$H NMR and FTIR spectroscopic techniques. The anticorrosion behaviour of IMNH on mild steel in 1M hydrochloric acid (HCl) medium was studied by potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques. The percentage inhibition efficiency of IMNH increased with increase in its concentration and temperature. The adsorption of IMNH followed chemisorption andobeyed Langmuir’s adsorption isotherm. PDP study revealed that IMNH functioned as a mixed type inhibitor. Theoretical study of the adsorption behaviour of this inhibitor was carried out by quantum chemical calculations using density functional theory (DFT). Scanning electron microscopy (SEM), atomic force microscopy (AFM) and energy-dispersive X-ray spectroscopy (EDX) studies confirmed the formation of a protective film of IMNH on the mild steel surface. • Synthesis, characterization and quantum chemical study of optoelectronic nature of ferrocene derivatives Two new ferrocene derivatives N-(2-hydroxy-5-methylphenyl) ferrocylideneamine (Fe1) and N-(2-hydroxy-5-chlorophenyl) ferrocylideneamine (Fe2) have been synthesized to study the effect on electronic, optical and charge transfer properties while changing the electron donating group with electron withdrawing group. The synthesized compounds were characterized by different spectroscopic (FTIR, UV–Vis,${}^1$H NMR,${}^{13}$C NMR) and spectrometric (EI) techniques. Thegeometries for ground and excited states were optimized by density functional theory (DFT/B3lyp/6-31G$^{**}$, LANL2DZ) and time-dependent DFT (TD-B3lyp/6-31G$^{**}$, LANL2DZ) levels, respectively. The absorption, fluorescence and phosphorescence spectra were estimated using TD-B3LYP and TD-wB97XD functionals and 6-31G$^{**}$basis set for C, H, N, O and LANL2DZ for Fe atoms in dichloromethane. • Atom probe analysis of Ni–Nb–Zr metallic glasses Atomic short arrangements of two Ni–Nb–Zr glassy alloys (doped and undoped) were examined through the 3D atomic reconstruction technique, atom probe tomography (APT). The chemical short configurations predicted accordingto two distinct theoretical models were compared with APT reconstructions, and inconsistencies were found. Additionally, diffraction experiments confirmed that the alloys under investigation were amorphous in nature. • Effect of amino-functionalization of MWCNTs on the mechanical and thermal properties of MWCNTs/epoxy composites The study investigates the tensile, flexural and thermal properties of epoxy resin matrix reinforced with pristine as well as amino-functionalized multi-walled carbon nanotubes (MWCNTs, 0, 0.25 and 0.50 wt%). The combination ofultrasonication and magnetic stirring has been used for the fabrication of MWCNTs/epoxy composite samples. The epoxy composite reinforced with 0.50 wt% amino-functionalized MWCNTs exhibits superior mechanical and thermal properties. The tensile and flexural strengths of this composite are noticed to be higher by about 13.5 and 17%, respectively, as compared with the neat epoxy specimen. The improvement in properties offered by amino-functionalized MWCNTs/epoxy composites is attributed to uniform distribution of MWCNTs in epoxy matrix as well as better interfacial adhesion between MWCNTsreinforcement and epoxy matrix,when compared with those noticed for epoxy composite reinforced with pristine MWCNTs. • Synthesis and characterization of inherently radiopaque nanocomposites using biocompatible iodinated poly(methyl methacrylate-$co$-acrylamide) and graphene oxide New inherently radiopaque nanocomposites were prepared using iodine-containing poly(methyl methacrylateco-acrylamide) and graphene oxide. For this purpose, P(MMA-$co$-AA) was synthesized via copolymerization of methylmethacrylate and acrylic acid, and modified with 4-iodophenyl isocyanate and 3,4,5-triiodophenyl isocyanate to form poly[(methyl methacrylate-$co$-(N-4-iodophenyl)acrylamide)] (1I-P(MMA-$co$-AA)) and poly[(methyl methacrylate-$co$-(N-3,4,5-triiodophenyl)acrylamide)] (3I-P(MMA-$co$-AA)), respectively. For comparative evaluation, the non-iodinatedcopolymer (PIC-P(MMA-$co$-AA)) was prepared via reaction of the P(MMA-$co$-AA) with phenyl isocyanate to investigate the effect of iodinated substituents on the morphology and thermal characteristics of the nanocomposites. All the nanocomposites were characterized by X-ray diffraction analysis, scanning electron microscopy, X-radiography and thermogravimetricanalysis. The results proved that thermal properties of the nanocomposites improved by the introduction of different amounts of graphene oxide into the copolymers’matrix. Radiopacity measurements showed the excellent radiopacityof iodinated nanocomposites and proved that 3I-GO-5 had radiopacity equivalent to that of an aluminium wedge with 2-mm thickness. • Growth, spectral, mechanical, electrical and optical characterization of guanidinium hydrogen succinate single crystal Slow evaporation method was employed to grow an organic crystal: guanidinium hydrogen succinate (GHS). Monoclinic structure of GHS was confirmed by single-crystal X-ray diffraction study and its space group was determined to be$P2_1/c$. Different functional groups present in GHS were estimated qualitatively by Fourier transform infrared analysis. The crystalline quality of the grown GHS was ascertained by high-resolution X-ray diffraction study. The UV–Vis absorption spectrum reveals a lower cut-off wavelength of 235 nm. The minimum absorption shows the wide optical transparency in the entire visible region.Work hardening co-efficient value ($n = 1.7$) shows that the GHS crystal belongs to soft material category. Behaviour of dipoles in the crystal was examined through dielectric study. The third-order nonlinear optical analysis wascarried out on GHS crystal through Z-scan technique. The nonlinear refractive index ($n_2$), nonlinear absorption coefficient ($\beta$) and third-order nonlinear optical susceptibility ($\chi^{(3)}$) were estimated to be$−5.78\times 10^{−8}$cm$^2$W$^{−1}$,$0.72\times 10^{−4}$cm W$^{−1}$and$8.09 \times 10^{−6}$esu, respectively. • Effect of tertiary butylpyridine in stability of methylammonium lead iodide perovskite thin films Perovskite material is a great visible light absorber in perovskite solar cells (PSCs). PSC has reported power conversion efficiency (PCE) of 22.1%. However, performance instability of the solar device base on this material hampersits commercialization. One of the factors responsible for performance instability in the cell is temperature. In this work, we carried out stability study of perovskite film treated with tertiary butylpyridine (tBP) as a surface modifier. Concentrationsof tBP added in perovskite material film were varied and the samples were subjected to temperature degradation test in a temperature-controlled chamber for 120 h. Ultraviolet–visible (UV–Vis) spectrophotometers, Fourier-transform infrared (FT-IR) spectrometers andX-ray diffractometers (XRD) were used to characterize the properties of the temperature-stabilitytested samples. The results show that the sample treated with 100$\mu$l of tBP has the best resistance to temperature degradation after the duration of the test. The surface-modified perovskite films, with 100$\mu$l of tBP, may reduce the degradation of PSCs. • Mesoporous$x$[Cu(II)O] nanoclusters dispersed and immobilized on$y$[SiO$_2$] matrix: structure and effective controlled biocidal activity against Pseudomonas aeruginosa and Bacillus subtilis Herein we report the synthesis of mesoporous nanostructures comprising copper (II) oxide {$x$[Cu(II)O]} immobilized on silica$y$[SiO$_2$] template for release of copper ions by precipitation via sol–gel technique. Three different specimens with increasing amount of Cu in the matrix with amount of Si being the same in all the samples, viz. ‘6Cu:5Si’, ‘4.5Cu:5Si’ and ‘3Cu:5Si’ where the numbers refer to the respective molar ratios of their respective domains, were prepared. Increase of crystallinity in the mesoporous material with increase in incorporation of copper domains consisting of CuO in SiO$_2$matrix has been established. The average size of the CuO nanoparticle (NP) (domain) is 20–30 nm. The BET surface area has been found to be 276–390 m$^2$g$^{−1}$and Langmuir surface area has been found to be 422–605.9 m2 g−1 for the samples5Si:3Cu–5Si:6Cu, respectively, having pore size of 4–6.5 nm. The cytotoxicity data show that the NPs are less toxic below concentration of 125$\mu$g ml$^{−1}$. A steady increase in percentage of bacterial-‘Escherichia coli’, ‘Pseudomonas aeruginosa’ and ‘Bacillus subtilis’ cell death (indicated by decrease in optical density) due to increase in concentrations of NPs after incubation for 14 h, showing sensitivity even at very low concentrations (5–20$\mu$g), has been observed. A comparative antibacterial activity test among the three prepared specimens has been reported, which shows better antibacterial activity with the lowest copper concentration. Better antibacterial sensitivity when compared with equivalent amount of commercial CuO is established. • Thermal stability and flame-retardant characteristic of irradiated LDPE and composites Magnesium hydroxide (MH) and alumina trihydrate (ATH) are extensively consumed as fillers in polyolefins to fabricate naturally responsive cables. Halogen-free wires, and especially cross-linked or thermoplastic elastomers, arefurther prevalent in worldwide use. The limited oxygen index (LOI), cone calorimeter, smoke density and thermogravimetry (TGA) experiments explain the thermal decomposition, flame-retardant and physical characteristics of samples. Results from studies of TGA, smoke emission and LOI testers showed that the thermal strength and flame-retardant characteristics of the samples containing MH compared with corresponding specimens containing ATH have superior thermal stability. The flame-retardant and heat resistance characteristics of samples were improved due to irradiation and the development of cross-linking bonds in the polymer framework. The results of the smoke density experiment show that adding MH to low-density polyethylene (LDPE) results in the lowest smoke density associated with LDPE and LDPE/ATH compounds. This study proved that the inclusion of MH and irradiation of specimens caused a greater thermal strength and also a superior flame-retardant polymeric product compared with the inclusion of ATH to similar irradiated specimens. These successes are useful and appropriate specifically for cable companies to deliver halogen-free flame-retardant cable materials. • Design of Permalloy–ferrite–polymer soft magnetic composites doped by ferrite nanoparticles and visualization of magnetic domains Soft magnetic composite materials were prepared by powder metallurgy technology. The composition of the new family of the materials was based on Permalloy type of ferromagnetic particles covered by Ni$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$nanoparticles. The spinel ferrite was prepared by electrospinning technology for achieving high-quality nanoparticles. A small amount of organic additives was included in final samples. The influence of magnetic ferrite dielectric coating on the magnetic properties of prepared composites was studied. The relatively high electrical resistivity leads to the real part of complex permeability up to 52 with stability up to high frequencies of about 1 MHz. SEM and TEM analyses were employed for composite characterization. The preparation of samples for magnetic force microscopic analysis is outlined in detail. The visualization of magnetic domain structure was done in order to understand the material behaviour of magnetic materials. • Crystallization and kinetics studies of Ti$_{20}$Zr$_{20}$Cu$_{60−x}$Ni$_x$($x = 10$, 20, 30 and 40) metallic glasses Synthesis and characterization of Ti$_{20}$Zr$_{20}Cu$_{60−x}$ Ni$_x$ ($x = 10$, 20, 30 and 40) metallic glasses are reported in this paper. Glassy ribbons are produced by rapid quenching using the standard copper wheel roller technique in argon atmosphere. Their structural characterization is carried out by X-ray diffraction (XRD) and thermal behaviour (crystallization) study by differential scanning calorimetry (DSC). Results of XRD on both sides of each ribbon sample confirmed that each sample was indeed amorphous/glassy as only a very broad peak in XRD pattern was observed. Metallic glass Ti$_{20}$Zr$_{20}$Cu$_{50}$Ni$_{10}$ shows three crystallization peaks in non-isothermal DSC scans while other three samples show only a single crystallization peak. The activation energy of crystallization for each sample has been calculated using three available models, namely, those of Kissinger, Augis–Bennett and Ozawa. All the three models gave nearly similar activation energies for a given sample within 10%.

• Characterization of organic light-emitting diode using a rubrene interlayer between electrode and hole transport layer

In this paper, we report the characteristic properties of an organic light-emitting diode (OLED) using a rubrene buffer layer over the fluorine-doped tin oxide (FTO) surface. Our study includes both electrical and optical properties of the device. Here, we study the OLED devices at different thicknesses of the buffer layer, which varies from 3 to 11 nm. For device fabrication, we use a thermal evaporation unit. Finally, we report that device performance in a bilayer anode form is always higher than that of a single-FTO-based device. Maximum device efficiency is found to be 6.31 cd A$^{−1}$ around 8-nm thickness of rubrene layer over the FTO surface.We also study the stability of both the single-layer and double-layer anode OLED devices. Through this study, we found that both device efficiency and luminance intensity of the bilayer anode OLED remain more stable for more number of days compared with the single-FTO OLED device.

• Microstructure and optical characterization of mechanosynthesized nanostructured TiSi$_x$N$_{(1−x)}$ cermets

Nanocrystalline cubic titanium silicon nitrides (TiSi$_x$N$_{(1−x)}$) with different Si concentrations have been synthesized at room temperature by mechanical alloying the stoichiometric compositions of ingredient powders in a nitrogenatmosphere. Structure and microstructure characterizations of unmilled and all ball-milled powders are carried out byanalysing respective X-ray diffraction patterns employing the Rietveld structure and microstructure refinement method.The presence of titanium, silicon and nitrogen in TiSi$_x$N$_{(1−x)}$ has been confirmed by energy-dispersive X-ray transmission electron microscopy analysis. Transmission electron microscopy image reveals that the average size of the spherical particles of 9-h-milled powder is $\sim$5 nm and size distribution is almost monodispersed, which corroborates well with the result of the Rietveld analysis. Bandgap energies of these solid solutions are determined by analysing respective UV–Vis absorption spectrum and it is found that the addition of silicon to insulating nanocrystalline TiN results in a reduction of bandgap energy and all solid solutions become wide-bandgap semiconductors with the addition of Si in different proportions.

• Effect of bismuth oxide nanoparticles on the physicochemical properties of porous silicon thin films

In this work, bismuth oxide nanoparticles were successfully deposited on porous silicon (PSi) in order to enhancethe light absorption and reduce the optical losses. The obtained bismuth oxide (Bi$_2$O$_3$)/PSi samples were characterizedby means of X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electronmicroscopy (SEM) combined with energy-dispersive spectroscopy (EDS), atomic force microscopy (AFM), photoluminescence(PL), UV–visible absorption and reflection spectroscopy techniques. The XRD studies revealed the formation of themonoclinic $\alpha$-Bi$_2$O$_3$ phase. The XPS analysis demonstrates the formation of highly pure Bi$_2$O$_3$ nanoparticles in accordance with XRD results. The SEM and AFM analyses confirmed that the bismuth oxide nanoparticles are well incorporated and uniformly distributed over the surface of PSi without changes in the arrangement and shape of the pores, resulting in an optimized microstructure. The Bi$_2$O$_3$/PSi films showed better absorption than PSi layers as indicated by UV–Vis absorption technique. The reflection measurements confirmed a further reduction in reflectivity of PSi from 6.4 to 3.5% after the inclusion of Bi$_2$O$_3$ nanoparticles, which is of significant importance for solar cells application since it can enhance its conversion efficiency. The Bi$_2$O$_3$/PSi films have a great promise to be used as efficient antireflection coatings in innovative concepts of higher efficiency and cost-effective solar cells.

• Investigation of optical properties and glass transition temperature of nano-epoxy matrix

In this research work, nanocomposites were synthesized by addition of fractions (0.0, 0.02, 0.04 and 0.06) of multi-wall carbon nanotubes (MWCNTs) to epoxy resin to investigate the optical properties and glass transition temperature. Optical measurement shows that epoxy matrix films have high absorption at the different MWCNTs fractions (0.0, 0.02, 0.04 and 0.06). The optical energy gaps for allowed direct transition were evaluated and found to decrease with increasing film fractions, precisely, from 2.85 to 1.32 eV when fractions increased from 0.0 to 0.06 of the matrix weights that indicated strong shifts at 435–935 nm with increasing fraction. The values of the absorption coefficient and extinction coefficientincreased with fractions of MWCNTs while the refractive index and the real part of dielectric constant decreased with the fractions of MWCNTs. Also, the glass transition temperature was investigated and was found to increase with increasing fraction of carbon nanotube in the matrix.

• Fabrication of micro–nano-roughened surface with superhydrophobic character on an aluminium alloy surface by a facile chemical etching process

In the present work, we have fabricated a superhydrophobic surface on aluminium alloy 2024 through a simpleimmersion chemical etching method in hydrochloric acid followed by a functionalization step in stearic acid solution. Theimpact of etching time on water contact angle was investigated and a contact angle of $\sim$167$^{\circ}$ was reached on the superhydrophobic surface, which was etched for 4 min. Morphology of the surface was evaluated by scanning electron microscopy and the surface chemical analysis was performed by energy-dispersive X-ray spectroscopy and Raman spectroscopy. We show that the fabricated superhydrophobic samples can besides water, also repel other liquids.We also demonstrate the selfcleaning properties of the fabricated samples using graphite particles as contaminants. Ultimately, we assessed the corrosionresistance properties of the fabricated surfaces by the potentiodynamic polarization method. The superhydrophobic surface exhibited increased corrosion potential and polarization resistance along with reduced corrosion current density, all of which are indicative of a significant improvement in corrosion performance of the superhydrophobic surface in comparison withtypical aluminium 2024. The cheap and facile superhydrophobic surface fabrication method presented in this study can beapplied to large scale samples with no need for electricity or expensive raw materials.

• Influence of NH$_4$Br as an ionic source on the structural/electrical properties of dextran-based biopolymer electrolytes and EDLC application

Biopolymer electrolytes (BPEs), consisting of ammonium bromide (NH$_4$Br) as the ionic provider and dextran(Leuconostoc mesenteroides) as the polymer host, are prepared by the solution cast technique. Interactions of cations from the salt have been confirmed with hydroxyl (OH) and glycosidic linkage (C–O–C) groups of dextran via Fourier transforminfrared analysis. Electrolyte with 20 wt% NH4Br maximized the ionic conductivity up to $(1.67 \pm 0.36) \times 10^{−6}$ S cm$^{−1}$. The trend of conductivity has been verified by field emission scanning electron microscopy, where the electrolyte surface became rough as the concentration of NH4Br exceeded 20 wt%. The contribution of ions as the main charge carrier in theBPE is confirmed by transference number analysis as $t_{\rm ion} = 0.92$ and $t_e = 0.08$. From linear sweep voltammetry, it is found that the highest conducting BPE in this work is electrochemically stable from 0 to 1.62 V. The fabricated electrochemical double-layer capacitor (EDLC) has been tested for 100 charge–discharge cycles and verified by cyclic voltammetry.

• Fabrication of MOF-177 for electrochemical detection of toxic Pb$^{2+}$ and Cd$^{2+} ions We have studied the electrochemical behaviour of room-temperature synthesized MOF-177. The MOF-177sample was characterized by various techniques like Fourier transform infrared spectroscopy, scanning electron microscopy,energy dispersive X-ray, powder X-ray diffraction, nuclear magnetic resonance and CHNS elemental analysis. The MOF-177 electrode was prepared and electrochemical performance was carried out to explore the electrical activity of MOF-177.Cyclic voltammetry studies were performed in 0.05 M K$_4$Fe(CN)$_6$solution and electrochemical sensing experiments were performed in 0.05MH$_2$SO$_4$and pH 7 buffer solution. A significantly increased electron transfer property has been observed and it has been explored for the electrochemical detection of heavy metal ions. The MOF-177/cp electrode has shown excellent sensitivity towards toxic heavy metal ions such as Pb$^{2+}$and Cd$^{2+}$at the limit of detection of 0.004 and 0.03$\mu$M, respectively. • Titanium-doped carbon and boron nitride nanocages (Ti–C$_{48}$and Ti–B$_{24}$N$_{24}$) as catalysts for ClO$+$1/2O$_2\to$ClO$_2$reaction: theoretical study The performances of Ti-doped carbon and boron nitride nanocages towards chloride monoxide (ClO) oxidation were examined. Details of mechanisms of oxidation of ClO on Ti-doped carbon and boron nitride nanocages were examined. Ti atoms of Ti–C$_{48}$and Ti–B$_{24}$N$_{24}$show catalytic activity towards ClO adsorption with low-barrier energies. Resultsdisplayed that the Ti-doped carbon and boron nitride nanocages oxidized ClO by the mechanisms of Eley–Rideal (ER) and Langmuir–Hinshelwood (LH). Catalytic activities in the LH path were limited by irremediable adsorption of chloridedioxide (ClO$_2$) on Ti–C$_{48}$and Ti–B$_{24}$N$_{24}$.While, in the ER path, the first and second ClO$_2$were separated, directly. Finally,the results proved that the Ti–C$_{48}$and Ti–B$_{24}$N$_{24}$show suitable catalytic abilities towards ClO oxidation via the ER path. • A kaolinite/TiO$_2$/ZnO-based novel ternary composite for photocatalytic degradation of anionic azo dyes Solar-assisted photocatalytic degradation of organic pollutants has emerged as efficient technology for the effective treatment of industrial wastewater. Here, we report a simple technique for the fabrication of a novel ternary photocatalystfrom kaolinite (K), TiO$_2$(T) and ZnO (Z). The most efficient catalyst was prepared at a calcination temperature of 60$^{\circ}$C. The fabricated ternary composite was characterized using different analytical techniques including Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, field emission-scanning electronmicroscopy and energy dispersive X-ray spectroscopy. The photocatalytic degradation was performed at room temperature (25$^{\circ}$C) using Remazol Red (RR), an anionic azo dye, as the model compound. A maximum of 98% degradation of RR was found with the ternary catalyst K$_{0.50}$T$_{0.45}$Z$_{0.05}$, which was prepared from 50% kaolinite (w/w), 45% TiO$_2$(w/w) and 5% ZnO (w/w). The catalyst was found to be suitable for long-term repeated applications. Mechanistic investigation through radical trapping experiments confirmed hydroxyl radicals as the potential contributor to the photocatalytic degradation of RR. It is highly expected that a novel photocatalyst design such as this will pave way towards further development ofmaterials capable of hazardous dye removal from industrial effluents. • A proof of concept for low-cost rechargeable aqueous aluminium-ion batteries In an effort to develop Al$^{3+}$ion-based rechargeable electrochemical cells, there is massive exploration of appropriate electrode materials in contemporary times. Aluminium is a natural choice due to its high abundance, low cost and easy processing. Herein, the working of rechargeable aqueous aluminium-ion batteries which comprise graphite from pencil sketch as the cathode, TiO$_2$as the anode and an Al$^{3+}$ion conducting aqueous electrolyte is demonstrated for the first time. The aluminium-ion cell delivers a discharge voltage of 1.5 V and stable specific capacities of 25 mAh g$^1{−1}$over 1000 cycles. This proof of concept emphasizes on the possibility of achieving sustainable, easy to assemble and low-cost rechargeable batteries. • Synthesis and evaluation of antibacterial properties of magnesium oxide nanoparticles In this paper we studied the efficiency of magnesium oxide (MgO) nanoparticles with an average size of 27 nm synthesized by a simple soft chemical method, in killing both Gram negative and Gram positive pathogenic bacteria. The antibacterial activity was determined by a minimum inhibitory concentration technique, agar cup method and live count technique. These nanoparticles show the maximum antibacterial activity towards Bacillus sp. in comparison with Escherichia coli. Transmission electron microscopy analyses of the treated-bacterial strains showed a morphological deformation with increased cell wall disruption. From the analysis of the antibacterial activity of MgO nanoparticles it is revealed that6$\mu$g ml$^{−1}$of dose is sufficient for killing Bacillus sp. whereas it is 7.5$\mu$g ml$^{−1}$for E. coli. These doses may be used in medical application. MgO nanoparticles could be used as antibacterial agents after completion of successful in vivo trials. • Synthesis of cerium-oxide NPs and their surface morphology effect on biological activities Herein, reliable work has been carried out on the synthesis of cerium-oxide (CeO$_2$) nanoparticles (NPs) viahydrothermal and co-precipitation methods. We emphasize the highly adequate hydrothermal method for synthesizingCeO$_2$NPs for biomedical applications. Absorption spectra showed peaks at 283 and 274 nm, which confirm the formationof CeO$_2$NPs for hydrothermal (HYNPs) and co-precipitation (CONPs) methods, respectively. Functional group analysisfirmly showed the presence of organic and inorganic species, which revealed similar characteristics of both HYNPs andCONPs. The cubic structure and the average crystallite size of the synthesized NPs are determined using Scherrer’s andWilliamson–Hall methods. The obtained average particle size is compared by using high-resolution transmission electronmicroscopy, which is around 10 and 5 nm for HYNPs and CONPs, respectively. Further, we studied their antimicrobial activities and consequently, the synthesized CeO$_2$NPs showed excellent antimicrobial activities. Moreover, HYNPs yieldedpromising antioxidant activity with the lowest IC$_{50}$as compared with CONPs. Owing to the biological activity of CeO$_2$NPs, HYNPs act as best therapeutic agents in biomedical applications as well as its vital role in antibiotics. • Constitutive modelling of Al7075 using the Johnson–Cook model In this paper, hot compression behaviour of Al7075 in the temperature range of 573–723 K and the strain rate range of 0.001–0.1 s$^{−1}$, based on standard requirements, was studied. The prediction of flow stress was performed using constitutive equations based on the basic and modified-Johnson–Cook model and the accuracy of the proposed models was estimated by comparing with the experimental results by the statistical error analysis method. Based on the experimental results, flow stress is changed significantly with changes in the strain rate and temperature. However, the basic model cannot predict the correlated effects of these parameters which decrease its accuracy of model, the flow stress of the materials especially at high temperatures. During the calculation of the constants based on the modified model, the effects of hardening and softening behaviour were included in addition to considering the correlated effects of the parameters. The accuracy of the modified model increased significantly when compared with experimental results. • First-principles computations of Y$_x$Ga$_{1−x}$As-ternary alloys: a study on structural, electronic, optical and elastic properties In this work, the first-principles computational study on the structural, elastic, electronic and optical propertiesof Y$_x$Ga$_{1−x}$As as a function of yttrium concentration ($x$) is presented. The computations are performed using the fullpotential linearized augmented plane wave plus local orbital method designed within density functional theory. Firstly,we performed our calculations on the most stable phases, NaCl and zinc blende, then their transition pressure for eachconcentration is determined and analysed. Our computed results for the zero yttrium concentration are found consistentwith the available experimental measurements as well as with theoretical predictions. Moreover, the dependencies of theseparameters upon yttrium concentration ($x$) were found to be non-linear.We also report computed results on electronic-bandstructure, electronic energy band gap results and density of states. A systematic study on optical properties to analyse itsoptoelectronic character and elastic properties is presented. • Cyclic oxidation of Ni–Fe$_2$O$_3$composite coating electrodeposited on AISI 304 stainless steel Protective coatings can be applied to enhance the performance of interconnects in solid oxide fuel cells. In this study, AISI 304 steel was coated with a Ni–Fe$_2$O$_3$composite to form a modified-Watt’s type electrolyte by the conventional electro co-deposition method. The characterization of the coatings before and after cyclic oxidation was performed by scanning electron microscopy and X-ray diffraction. In order to evaluate the oxidation behaviour, thermal cycling was carried out in a furnace at 850$^{\circ}$C. The results indicated that the coated steel had better oxidation resistance in comparison with the uncoated steel. After 60 cycles of oxidation, the Ni–Fe$_2$O$_3$composite coating was converted to FeNi$_2$O$_4$, NiCrO$_4$, MnFe$_2$O$_4$and Fe$_2$NiO$_4$. The Fe$_2$O$_3$/NiFe$_2$O$_4$composite coating reduced the outward migration of chromium and the growth rate ofthe Cr$_2$O$_3$layer. • The effect of shape and size of ZnO nanoparticles on their antimicrobial and photocatalytic activities: a green approach In this paper, ZnO nanoparticles (NPs) having potent photocatalytic and antimicrobial activities have been synthesized by using the aloe vera plant extract. The ZnO NPs have been synthesized using (Zn(CH$_3$COO)$_2$·2H$_2$O) (5, 10 and 50 mmol kg$^{−1}$), at temperature 70$^{\circ}$C and pH 11.5. The synthesized NPs were examined using UV–Visible, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy(TEM) characterization techniques. TEM analysis confirms the synthesis of ZnO NPs with hexagonal, spherical, cylindrical and cuboidal shapes decorated under different concentrations of precursor metal salt. UV–Visible studies revealed thatZnO NPs have a wide energy band gap varying from 3.36 to 3.43 eV. The synthesized ZnO NPs were examined for the photocatalytic degradation of methyl orange dye which resulted in up to 95% degradation. ZnO NPs are also inspected for the antibacterial activity against Bacillus subtilis (MTCC 441), Staphylococcus aureus (MTCC 737) and Escherichia coli (MTCC 739) pathogenic bacteria. • Investigation of flow behaviour and lubrication capabilities of MoS$_2$Flow behaviour of lubricants largely depends on their rheological properties which in turn strongly influence their lubrication capabilities and ultimately the machine life. Modern chemistry plays a great role in the synthesis of nano-additives that help in enhancing the rheological and tribological properties of the lubricants. In the present study, the rheological and tribological studies of MoS$_2$nanofluids are presented in order to determine their flow behaviour and lubrication capabilities. For studying the effect of MoS$_2$nanoparticles on the flow behaviour and lubrication capabilities of lubricants, two commercially available blended synthetic engine oils of SAE grades 5W-40 were selected. MoS$_2$nanoparticles were synthesized by hydrothermal methods. Surface modification of the synthesized MoS$_2$nanoparticles was performedbefore blending them with the base lubricants in 0.1, 0.15 and 0.2% concentrations. Standard ASTM and IS procedures were used to determine physicochemical properties and tribo-performance behaviour of oils, respectively. The rheological parameters of MoS$_2$nanofluids were determined using a rheometer. The study reveals that tested MoS$_2$nanofluids behavedas non-Newtonian lubricants with shear thinning behaviour at all tested temperatures and exhibited viscoelastic behaviour at small-shear rates. As a result of this anti-wear property showed a significant enhancement up to 20% for 0.2% MoS$_2$indicating better anti-wear properties of MoS$_2$nanofluids. However, a marginal reduction in friction for the tuning of 4% observed for 0.2 wt% of MoS$_2$nanoparticles in the tested lubricants indicates that finished products have little scope to improve anti-friction properties under the influence of the already present additives. • Antibacterial activity of ZnO nanoflowers deposited on biodegradable acrylic acid hydrogel by chemical bath deposition In the first part of this study, acrylic acid (AA) hydrogels were produced by a free radical reaction. Chemical and morphological structures of AA-hydrogels were specified by using Fourier transform infrared (FT-IR) spectroscopy andscanning electron microscopy (SEM) techniques. In the second part of the study, ZnO nanoflowers were synthesized on the AA-hydrogel by using a chemical bath deposition (CBD) technique for the first time in the literature. The AA-hydrogel acted as the substrate in the CBD process. The deposition time effect on the morphological properties of ZnO nanoflowers was determined by applying SEM. According to the SEM results, the deposition time in the production of ZnO nanoflowers has played a vital role in the surface morphology. Chemical, morphological and thermal properties of the ZnO nanoflowers were determined by applying FT-IR, scanning electron microscopy-energy dispersive X-ray spectroscopy and thermogravimetric analysis techniques. Elemental mapping of ZnO nanostructures was carried out using SEM. The antibacterial activity of theZnO nanoflower-deposited AA-hydrogel was determined against Gram-negative and Gram-positive bacteria. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as test microorganisms. Gram-negative bacteria were moreresistant to hydrogels and ZnO nanoflowers compared to Gram-positive bacteria. • A remarkable enhancement between optical transparency and SHG efficiency on doped-KHP single crystals Potassium hydrogen phthalate (KHP) single crystals are non-linear optical materials and their transmittance window are remarkably enhanced by an organic dopant such as resorcinol. The present study was mainly focused on the growth and characterization of the single-crystal KHP doped with resorcinol which was synthesized by a slow evaporation solution technique and its dimension was found to be$8 \times 7 \times 2.75$mm$^3at ambient temperature. Vibrationalassignments of the functional groups confirmed the presence of dopants. The optical behaviour of the grown crystal was explored by ultraviolet–visible–near-infrared studies which result in 99% of the transmittance with the cut-off wavelength of 250 nm. The mechanical property was analysed by the Vickers microhardness test. The apparent microhardness increases with increasing applied indentation load revealing the reverse indentation size effect behaviour. Organic impurity increases the second harmonic generation efficiency of KHP, suggesting that the molecular alignment in the presence of resorcinolresults in enhanced non-linearity. • Silicone rubber composites fabricated using KH550-modified poplar leaves graphene Silicone rubber (SR) composites were fabricated using poplar leaves graphene (PG). PG was synthesized from poplar leaves and modified-poplar leaves graphene (MPG) was obtained by treating graphene with a silane coupling agent\gamma$-aminopropyltriethoxysilane (KH550). The biosynthesized PG and MPG were characterized by using organic elemental analysis, X-ray photoelectron spectroscopy, atomic force microscopy and scanning electron microscopy (SEM). The PGmodified SR composites were studied by using their mechanical properties, Fourier transform infrared spectroscopy, SEM and thermogravimetric analysis. The results showed that the PG synthesized by poplar leaves had high-carbon content and purity. The MPG was more evenly dispersed into SR than the PG, the mechanical properties of the MPG/SR composites were better than those of the PG/SR when the MPG content was 0.1 phr (parts per hundred rubber), the tensile strength and elongation at break were increased by 36.2 and 19.4% respectively and the wear resistance was increased by 57.1%. The thermal stability of the MPG/SR was higher than that of the PG/SR and SR. This important discovery could not only solve the problem of the origin of graphene, but also broaden the application of SR composites. • Investigating the role of amides on the textural and optical properties of mesoporous-nanostructured$\theta$-Al$_2$O3 Mesoporous-nanostructured$\theta$-Al$_2$O$_3$was synthesized by an autoclaving technique using different amidesi.e., formamide (F), dimethyl formamide (DMF) and diethyl formamide (DEF) at 150$^{\circ}$C/24 h followed by calcinationat 1000$^{\circ}$C. Crystallization and structural behaviour of the as-synthesized materials were characterized by X-raydiffraction and Fourier transform infrared spectroscopy. The porosity study was carried out by N2 adsorption–desorption(BET) technique. Microstructural features were measured by transmission electron microscopy (TEM). The amidebasedsolvents played a deliberate role in microstructural and textural features of$\theta$-Al$_2$O$_3$. The DMF-based solventshowed an enhanced surface area of 158 m$2^$g$^{−1}$. The as-prepared$\theta$-Al$_2$O$_3$rendered a nano-sheet, nano-rod and nano-flake like morphology for F, DMF and DEF derived products, respectively. From the UV–Vis spectroscopic measurement, the estimated band-gap of$\theta$-Al$_2$O$_3$was found to be 5.16–5.40 eV. Photoluminescence investigation further revealed blue emission particularly for excitation at a wavelength of 252 nm. A DMF-derived sample rendered thelowest band gap due to its smaller crystallite size and higher surface area compared to that of F- and DEF-derivedsamples. • Comparative machinability characterization of wire electrical discharge machining on different specialized AISI steels In this work, we have attempted to prepare a comparative machinability study of wire electrical discharge machining of different difficult-to-machine materials, viz., stainless steel (SS) 316, H21 hot work tool steel and M42 highspeedsteel (HSS). The key features, which are compared during the analysis, are mainly material removal rate, average surface roughness, kerf width, wire consumption rate (WCR), recast layer (RL), elemental diffusion, surface morphology and micro-hardness of the machined surface. They are found to be greatly influenced by pulse energy. The pulse energy is calculated in terms of ‘specific discharge energy’. Apart from the discharge energy, the thermal conductivity of the material also plays an important role in the formation of RL and inclusion of foreign elements such as carbon, oxygen, copper andzinc in RL. H21 steel has been found to be more prone to thermal defects due to its high-thermal conductivity and high tensile residual stresses, whereas more re-solidification of foreign materials is observed in SS316 and M42 HSS due to theirhigh adhesive properties and low-thermal conductivity. But, in low-energy cutting, more uniform surfaces are observed in H21 steel in comparison with other two types of steel. • Enhanced topical econazole antifungal efficacy by amine-functionalized silica nanoparticles The present study aims at developing efficient econazole (ECO) platforms as topical creams for the treatment offungal skin infections. The hexagonalmesoporous silica nanoparticle, known as MCM41,was synthesized and functionalized by aminopropyl groups (MCM41-NH$_2$). Various ECO concentrations were loaded into MCM41 and MCM41-NH$_2$(MSNs); the optimized complexes with the highest entrapment efficiencies were characterized by X-ray powder diffraction, scanning electron microscopy (SEM) and gas-volumetric analysis (BET). SEM images showed a spherical shape of the parent nanoparticles—higher drug loading and incorporation into the nanoparticles were obtained by amino-functionalized MCM41. Cytotoxicity assays of MCM41 and MCM41-NH$_2$and the ECO inclusion complexes elucidated no toxicity to human dermal fibroblast cell lines. Enhanced antifungal activity against Candida albicans was observed for ECO/MCM41-NH$_2$compared with ECO/MCM41 and simple cream. No irritation was observed by the cream containing ECO/MSN application on white male rabbit skin after 72 h. MSNs were stable within 1 year storage. ECO-loaded silica nanoparticles can be considered for the development of reliable alternatives to ECO cream for the treatment of skin fungal infections. • Synthesis of ZrO$_2$nanostructure for gas sensing application ZrO$_2$nanopowder has been synthesized by the conventional precipitation method for gas-sensing application. The synthesized powder was dropcast and subsequently annealed at 100$^{\circ}$C. The drop-casted film has been subjected to X-ray diffraction analysis, scanning electron microscopy, ultraviolet–visible diffuse reflectance spectroscopy, photoluminescence study and$I –V$measurement in order to observe its structural, morphological, optical and electrical properties. The gas sensing measurement has been performed for the thus prepared ZrO$_2$film by an exposure to different reducing gases(ammonia, ethanol, formaldehyde, acetone and xylene) at different temperatures for various gas concentrations. It has been observed that the film shows a better response towards ammonia (about 18%) compared to all other gases due to faster diffusion. Also, a quick response and recovery time have been found as 70 and 70 s, respectively, for ammonia. • High-temperature corrosion of aluminized-AISI 1020 steel with NaCl and Na$_2$SO$_4$deposits High-temperature corrosion of aluminized-American Iron and Steel Institute (AISI) 1020 steel with sodium chloride (NaCl) and sodium sulphate (Na$_2$SO$_4$) deposits was studied using isothermal oxidization in a dry air environment at 700$^{\circ}$C for 49 h. NaCl and Na$_2$SO$_4$deposits on the aluminide layer interfered with protective alumina/aluminium oxide(Al$_2$O$_3$) scale formation on the steel substrate. Chlorine and sulphur gases (Cl$_{2g}$and S$_g$, respectively) released into the atmosphere corroded the protective Al$_2$O$_3$layer. Corrosion of the Al$_2$O$_3$layer was also due to local formation of iron oxide (Fe$_2$O$_3$). Fe$_2$O$_3$growth is attributed to ferric chloride (FeCl$_3$) vaporization. S$_g$diffusion into the Al$_2$O$_3$scale via Al$^{3+}$vacancy defects led to the formation of aluminium sulphide on the aluminide layer surface. Cl and S consequently induced hot corrosion of the aluminized steel, thereby increasing cyclic oxychloridation and sulphidation rates at high temperatures. • An in vitro comparative study of layered-double hydroxide nanoconjugate in the delivery of small interference and short-hairpin ribonucleic acid Alzheimer’s disease is a disease which cannot be cured completely. In this aspect ribonucleic acid interference(RNAi) therapy is a prospective therapeutic mechanism which can be used for identifying a future curative procedure. RNAitherapy comprises small interfering RNA (siRNA), short hairpin (shRNA) and micro-RNA therapeutics. Within these threemechanisms we have identified two of them as an effective method of combating this genetic incurable disease. siRNAs andshRNAs are very much effective in vitro that is already proved in many research work. In our study we have used a very potent, biocompatible nanoparticle-layered double hydroxide for delivering these macromolecules. However, the intercalation and cellular internalization of these macromolecules demonstrated significant differences. As siRNAs have low-molecular weight than shRNAs they demonstrated different characteristics in the case of internalization within layered-double hydroxide and while cellular internalization. At the end of this study it has been found that both of these macromolecules may be used as a therapeutic approach of Alzheimer’s disease after studying it in future in animal and human subjects. • Adsorption of benzene, aniline and benzoic acid in water by fullerene (C$_{60}$) and fullerene nanowhiskers Most aromatic hydrocarbons and their derivatives are harmful organic molecules. Despite their low solubility, trace amounts of aromatic hydrocarbons can be present in water. If water is contaminated by aromatic hydrocarbons, it isvery difficult to remove these from water. Through contaminated water, these compounds can exert deleterious effects in plants and animals, as well as on human health. Fullerenes and their derivatives typically exhibit hydrophobic characteristics, and are therefore considered as good adsorbents for the removal of aromatic hydrocarbons. Herein, the removal of benzene,aniline and benzoic acid by fullerene and fullerene nanowhiskers was evaluated. While benzene was removed satisfactorily from water, aniline and benzoic acid were not, owing to the presence of ionized functional groups. However, adjustment of the solution pH to values where the functional groups of aniline or benzoic acid do not have any charge, resulted in an increase in their adsorption. High pH values were found to have a positive effect on the removal of aniline, while low pH values were beneficial for the adsorption of benzoic acid. Fullerenes and fullerene nanowhiskers were thus found to be promising adsorbents for the removal of aromatic hydrocarbons. • Study on the corrosion and wear characteristics of magnesium alloy AZ91D in simulated body fluids Bioimplants made of metallic materials induce a stress-shielding effect and delayed osteoblast activity during in-vivo experiments. Bioimplants also suffer corrosion, wear and combined effect of corrosion–wear during their service time. Bioimplants made of magnesium alloys result in a negligible stress shielding effect, owing to their similarity with bone’s elastic modulus. However, the soft matrix of the magnesium alloy is susceptible to high-wear rates. In this study, magnesiumalloy AZ91D is subjected to the corrosion test (immersion and electrochemical), adhesive wear and simultaneous corrosion–wear test to test the significance of the body fluid in the corrosion–wear rate of the bioimplants. The surface morphology,elemental composition and phase composition of the specimens are characterized using field emission scanning electronmicroscopy, energy dispersive X-ray spectroscopy and X-ray diffraction analytic techniques. The results indicate that thesimulated-body fluid has a significant effect on the corrosion rate and corrosion–wear rate of the specimens. • Candle soot-coated egg carton material for oil water separation and detergent adsorption A hydrophobic and superoleophilic adsorbent was prepared by coating candle soot (CS) on the surface of a recycled egg carton material (ECM). This waste material has been explored as a cost-effective adsorbent to remove oiland detergent from water. The surface of the material was coated with CS solution prepared by mixing soot with acetone and characterized by scanning electron microscopy and contact angle measurements. The rate of fall of contact angle for water and oil was evident of water rejection and oil absorption capability of the coated-waste material. Further, the effect of temperature on the contact angle between water and surface was observed. The carbon-coated ECM demonstrates good absorption capacity with oils of different densities, without pre-treatments and surface modifications. It also shows its capability to absorb detergent from water with a pH value declining towards 7. Thus, a waste material can act as an effective alternative for filtering of oil and detergent water for households and industries. • Enhancement of impact strength of poly(lactic acid)/silicon carbide nanocomposites through surface modification with titanate-coupling agents In this study, poly(lactic acid) (PLA)-based nanocomposites were fabricated from PLA and silicon carbide (SiC) using solution blending. The surfaces of SiC nanoparticles were treated with a titanate-coupling agent. The influence of the SiC content on thermal stability, flexural properties, impact strength and fracture morphology of the nanocomposites was investigated. The impact strength of the nanocomposites was increased by the introduction of SiC nanoparticles. The nanocomposites containing SiC nanoparticles treated with a titanate-coupling agent (termed T-SiC) exhibited higher impact strengths than the nanocomposites containing neat SiC nanoparticles under the same conditions. Scanning electron microscopy results showed good compatibility between the T-SiC nanoparticles and the PLA matrix. • Self-support wood-derived carbon/polyaniline composite for high-performance supercapacitor electrodes Wood-derived carbon is a neoteric self-supporter electrode material for supercapacitors or batteries. To improve the electrochemical characteristics, polyaniline (PANI) was deposited on wood carbon (WC) by an in-situ polymerization method. The sandwich-like symmetrical solid-state supercapacitor was developed by preparing WC/PANI composites andtheir electrochemical properties were examined. The device showed an excellent capacity retention and displayed the maximum specific capacitance of 22.5 mF cm$^{−2}$at a scan rate of 10 mV s$^^{−1}$. It was also demonstrated an excellent electrical conductivity and an outstanding retention of$\sim$82%. It was suggested that the PANI accommodated into WC without any significant morphological change during the charge–discharge cycling of the hybrid WC-based composites. The microstructure and chemical structure of WC/PANI composites were also characterized by the Fourier-transform infrared, Ramanspectroscopy and X-ray diffraction techniques. • Synthesis and electrochemical properties of Co-doped ZnMn$_2$O$_4$hollow nanospheres Spinel structure Co-doped ZnMn$_2$O$_4$nanocrystals were successfully synthesized by a hydrothermal method. The effects of Co-doping concentration on the structure and electrochemical properties of the samples were investigated.The experimental results manifest that all samples exhibit a single-phase with a tetragonal structure, and morphologies are regular hollow microspheres. Cyclic voltammetry curves for all samples are similar to a rectangular shape with symmetric nature and no obvious redox peak.Galvanostatic charge–discharge curves were triangular and symmetric. Impedance spectra revealed that Zn$_{1−x}$Co$_x$Mn$_2$O$_4$possess low resistance. Better electrochemical properties of the ZnMn$_2$O$_4$electrode could be obtained when the Co-doping ratio is 0.3. Zn$_{0.7}$Co$_{0.3}$Mn$_{2}$O$_4$exhibits much higher specific capacitance (306 F g$^{−1}$) at a scan rate of 5 mV s$^{−1}$, and shows excellent cycling stability and retains 98.2% of its initial capacitance after 1000 cycles. The enhanced capacitive performance in this work can be attributed to the incorporation of Co ions doped into the ZnMn$_2$O$_4$host lattice. • Removal of Cu(II), Co(II) and Cd(II) from water solutions by layered-double hydroxides with different [Mg(II)]/[Fe(III)] molar ratios This work presents a study of sorption of heavy metals (HMs)—Cu(II), Co(II) and Cd(II)—from water media by carbonated and calcined forms of layered-double hydroxides (LDH) with various Mg(II)/Fe(III) molar ratios, whichare obtained by precipitation. It is ascertained that the maximum sorption (99.9%) of the HM ions stated is observed with the use of calcined forms of LDH at pH > 2.8 (pH after sorption$\geq$8.3). Such an increase in the pH of the aqueous suspension causes sorption of the HM ions by the mechanism of their precipitation in the form of hydroxides or hydroxocarbonates (for Cu(II)). Sufficiently high degrees of sorption of HMs, even at low pH of the aqueous medium, are apparently caused not only by the precipitation of their hydroxide forms, but also due to the complex formation with ferrinol groups of brucite sorbent layers. An increase in the Mg/Fe ratio from 2 to 4 and a corresponding decrease in the positive charge of the layers, which determines the size of the interlayer space in the LDH, have virtually no effect on the degree of extraction of HMs. The presented results suggest that the use of the studied-LDH in practice might be promising. • Effects of different polymers and solvents on crystallization of the NaYF$_4$:Yb/Er phase Up-converting NaYF$_4$:Yb,Er nanoparticles were obtained by polymer-assisted solvothermal synthesis using a common solution of hydrated RE nitrates in ethanol or ethylene glycol. It was shown that polymer choice (polyacrylic acid—PAA, polyvinylpyrrolidone—PVP and chitosan—CS) controls the size and shape of NaYF$_4$:Yb,Er nanoparticles, while the solvent type and pH value affect their crystallinity. Consequently, the spherical nanoparticles of a cubic ($\alpha$) phase, the average size of which ranged from 60 to 140 nm, were obtained either when PVP/ethanol or PVP/ethylene glycol were used solely during synthesis, whereas NaOH addition induced hexagonal ($\beta$) phase nucleation. The formation of the hierarchically organized spherical aggregates and nanofoils was observed when CS and PAA were used during synthesis, respectively. The average crystallite size, microstrain, doping level, lattice parameters, as well as, the presence of the certain ligands on the particle surface were determined and correlated with the intensity of visible-light emission observed under 980 nm laser-diode excitation. • Some aspects of new Cu(NbC) films In this study, new barrier-free Cu(NbC) alloy films with two different thicknesses, i.e., 8 and 300 nm, containing 0.3 at% C and 0.5 at% Nb, which are deposited via co-sputtering on three types of substrates, viz., Si, stainless steel and polyimide (PI), have been developed, annealed, measured and analysed. The resistivity value of the new 300-nm-thick films atop Si substrates is 3.07$\mu\Omega$cm after annealing at 450$^{\circ}$C for 200 h. The low resistivity and diffusion depth of the new films exhibit their good quality in anti-oxidation stability in a high-temperature environment. The films also display high-adhesive strength atop either stainless-steel or PI substrates,$\sim$7–8 times greater than that of their pure-Cu counterparts. In sharp contrast, the antibacterial ratio of the new films is$\sim\$96% while that of their pure-Cu counterparts is 0%. In addition, the contact angles of Cu(NbC) films are greater than those of their pure-Cu counterparts, resulting in a far superior antibacterialefficacy for the new films to pure-Cu films against, for example, Staphylococcus aureus BCRC 10451.With these desirable merits, the new films seem to be a good candidate material for bacteria killing and prevention, reduction of legionella spread inside hospitals and/or large buildings, biological medical care systems and advanced surgical tools. The new films deposited on PI substrates also seem to be suitable for making supple electrically conductive parts or devices, such as flexible panels, keyboards, screens, smartphones embedded in smart textiles and so forth.

• # Bulletin of Materials Science

Volume 43, 2020
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019