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Different nanoparticles (NPs) including S1, S2, S3, S4, and S5 are prepared, using the co-precipitation route. The substitution of Co and Ni into the SnO2 matrix brought considerable modification in the physical attributes of all co-doped samples. The XRD data reveal that the calculated crystallite size is reduced from 10.54 to 1.65 nm with piling up oxygen vacancies (OVs) concentration when the Co content varies from 2.2 to 11 mM. The insertion of Co and Ni in SnO2 (lattice) produces ample alteration in the material traits of all samples. The dielectric properties strongly exhibit doping dependence. The dielectric measures including (dielectric loss e′, dielectric loss factor tan δ, and AC conductivity σac ) are varied with growing Co content and achieved the utmost values for S4 NPs. The tanδ shows the dispersive nature, and relaxation peaks are identified, in which intensities are enhanced with growing Co content. The dielectric behavior and σac variations show that the dispersion is induced by polarization at the interfaces due to OVs and hopping processes. All these materials (samples) are interesting for device applications due to their large dielectric constant. The appearance of hysteresis loops show ferromagnetic nature with enhancement in saturation magnetization arises from a substantial measure of induced OVs (defects) by co-doping in the system (samples). The current work shows the doping-induced variations in dielectric and magnetic attributes. The OVs produce ferromagnetic behavior in (Ni, Co) co-doped SnO2 NPs applicable in high-frequency dielectric devices, and spintronics.

A new feature of electromagnetic radiation is studied by investigating the Rayleigh–Taylor (RT) instability in a radiative electron–ion magnetoplasma. Within the adiabatic limit, the linear RT instability supports against the gravity and is primarily provided by the radiation pressure, which is a complicated function of both temperature and density concentration of electrons. It is examined that, for superdense plasma environments, the radiation pressure becomes comparable or even more than the usual gas pressure, which may lead to enhance the growth rate of RT instability via varying the electron temperature and density concentration. Diamagnetic drifts are also taken into account due to the presence of thermal and radiation pressures apart from the gravitational drift. The results of RT instability are significantly affected by the variation of radiation pressure in dense magnetized nonuniform plasmas and have relevance for understanding dense astrophysical environments, such as massive star clusters and white dwarfs.

Oxygen vacancies (O.Vs) play vital role in tailoring structural, optical and dielectric properties of nanostructures. Here we prepared SnO2/graphite (SG) nanocomposite by growing SnO2 nanoparticles on graphite sheets via hydrothermal method. Enhanced dielectric behavior due to increase in the oxygen vacancies (O.Vs) has been observed in SnO2/graphite (SG) nanocomposite synthesized. To reveal the underlying origin here, we investigated the structural, morphological, optical, electrochemical and dielectric properties. The growth of SnO2 NPs on graphite sheets resulted in small-sized NPs (Average size 10.89 ± 0.24 nm) inducing stresses in the structure causing large defect density (O.Vs). The formation of SG nanocomposite has been validated via SEM, TEM, EDX and FTIR. EDX, XPS and Photoluminescence (PL) spectra of SG nanocomposite manifest the presence of large oxygen vacancies (O.Vs). It is revealed that the bandgap of the host material SnO2 (from ultra violet to the visible window) can be engineered by controlling the assimilation of SnO2 NPs on GNs. SG nanocomposite exhibits reversible redox process with high anodic and cathodic currents, low internal (0.47 Ω) and charge transfer (4.08 Ω) resistances, correspondingly, low voltage drop (IR) 0.56 V and high capacitance 54.8 F/g. Variations in dielectric constant (ɛ), dielectric loss ( $$\varepsilon^{\prime\prime}$$ ) and conductivity (σac) are attributed to the increased concentration of O.Vs and introduction of conductive carbon (graphite). The variations in dielectric properties are attributable to Maxewell–Wagner interfacial polarization and hopping process.

Single-phase lead-zirconate-titanate (PZT) perovskite nanofibers, with $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ composition were synthesized using the electrospinning technique. Poly-vinyl-pyrrolidone (PVP) was used as viscosity controller, size and uniformity of the $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ nanofibers were optimized against different PVP concentrations. The results showed that PVP concentrations play a significant role in the fabrication, homogeneity, uniformity, porosity, and particularly in the diameter of PZT nanofibers. SEM and XRD results revealed the formation of sing-phase $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ nanofibers at 600 °C with an average diameter of ~ 96 nm. The prepared PZT nanofibers exhibited a significantly wide bandgap (~ 3.5 eV) and a high dielectric-constant (~ 1827). The device of single-phase PZT nanofibers was fabricated on interdigitated electrodes to study the current–voltage, impedance spectroscopy, and dielectric characteristics of the PZT nanofibers. The current–voltage characteristics of the fabricated device with PZT nanofibers showed non-ohmic properties. The non-linear I–V characteristics at temperatures between 308 and 408 K indicate two distinct regions. Impedance spectroscopy indicated the presence of non-ideal Debye type behavior in $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ nanofibers and was ascribed to the existence of heterogeneity in the sample. The measured capacitances were assigned to two electro-active regions in the prepared $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ nanofibers. A proto-type piezoelectric nanogenerator based on PZT nanofibers was fabricated to study the piezoelectric properties of $${\text{Pb}}\left({\text{Zr}}_{0.5}{\text{Ti}}_{0.5}\right){\text{O}}_{3}$$ nanofibers. PZT nanofibers were aligned on interdigitated electrodes of silver wire, which demonstrated piezoelectric performance and delivered an output voltage of ~ 40 V under periodic stress applications.

Fabricating earth-abundant bifunctional water splitting electrocatalysts with high efficiencies to replace noble metal-based Pt and IrO2 catalysts is in great demand for the development of clean energy conversion technologies. Molybdenum disulfide (MoS2) nanostructures have attracted much attention as promising material for hydrogen evolution reaction (HER). The production of hydrogen gas by help of potential efficient earth abundant metal oxides, and stable electrolysis seems a promising for hydrogen evolution reaction pathway in 1 M potassium hydroxide electrolyte media is a hot research topic in the field for clean energy conversion, renewable energies and storage. Here we propose asystem composed NiO nanostructures and MoS2 deposited on (MoS2@NiO). Here, by hydrothermal method NiO prepared and MoS2@NiO by an electrospinning technique complex, can be used as catalyst to produce a large amount of hydrogen gas bubbles. The NiO nanostructures composite having highest synergistic behavior fully and covered by the MoS2. For the MoS2@NiO nano composite catalyst, experiment applied in 1 M KOH for the production of hydrogen evolution reaction which exhibits distinct properties from the bulk material. Overpotential values recorded low 406 mV and current density 10 mA cm−2 measured. Co-catalysts characterized by using different techniques for deep study as scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Owing to their unique structure, as-prepared nanocomposite exhibited enhanced catalytic performance for HER due to high electroactive surface area and swift electron transfer kinetics. Based on the HER polarization curves at low potential electrochemical to examine the effects of intercalants HER catalytic efficiency. Our findings establish low Tafel slope (44 mV/decade) and the catalyst stable for at least 13 h. This simple exploitation of MoS2@NiO composite catalysts depending on the intended application of their electrochemistry.

In this study, a co-dopant CGO was synthesized to produce more efficient cathode materials for intermediate temperature solid oxide fuel cell (IT-SOFC) applications. Neodymium (Nd) was doped into CGO in four different weight ratios in the formula NdxGd0.15Ce0.85-xO2-δ (NGCO); the selected percentages for x were 1%, 3%, 5% and 7%. XRD patterns showed pure phase for all synthesized compositions and good compatibility at high temperature under static air with the most common ceramic cathode material in IT-SOFC (La0·60Sr0·40Co0·20Fe0·80O2-a, LSCF). Impedance spectroscopic characterization of symmetrical cells of the composite NGCO-LSCF at different temperatures (650–800 °C in steps of 50 °C) and a frequency range of 0.1–1 MHz in synthetic air revealed interesting results. The lowest polarization resistance (Rp) was achieved for Nd0.05Gd0.15Ce0·80O2-δ (0.06 Ω cm2 at 800 °C, 0.17 Ω cm2 at 750 °C, 0.31 Ω cm2 at 700 °C, and 0.59 Ω cm2 at 650 °C). The expected decrease in Rp was not observed for the sample with higher Nd content (7% Nd). Thus, it can be said that there is a distinction between the compositions Nd0.05Gd0.15Ce0·80O2-δ and Nd0.07Gd0.15Ce0·78O2-δ; the co-doping of Nd in NGCO incremented the oxygen ion diffusion path, thereby optimization in the triple phase boundary (TPB) sites was obtained. Furthermore, SEM and TGA measurements were conducted to clarify the reasons of such improvements. This work showed that an NGCO-LSCF composite can be considered as a potential candidate for cathode material for future IT-SOFC applications.

Herein, we report the characterization of CuO nanostructures annealed at different temperatures, synthesized by chemical co-precipitation method. It is found in the XRD patterns that the peaks were broader at low temperatures due to increased defect density and poor crystallization suggesting that increasing annealing temperature enhances the degree of crystallization of the samples. Scanning electron microscopy (SEM) suggests that the CuO nanostructures change with increasing annealing temperature from rods to disc-shaped particles. It is observed in PL that with the increase in annealing temperature, the emission intensities increase for the same morphology due to the increase in oxygen vacancies (O.Vs) and improvement of crystallization. The dielectric constant has been increased with increasing temperature for the same morphology and is maximum for the sample annealed at 600 °C which is mainly due to the RDP and SCP. The relaxation peaks are shifted to the higher frequencies due to defect dipoles. Enhancement in conductivity is due to the growth of conducting grains. Our findings may provide comprehensive insight in designing high-performance electronic devices.

The present study shows the synthesis of silver nanoparticles (Ag NPs) using a methanolic and aqueous extract of R. stricta. UV–visible spectroscopy, energy-dispersive X-ray diffraction (EDX), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FTIR) techniques were used to further characterize the Ag NPs. UV–visible spectra give surface Plasmon resonance (SPR) at 490–560 nm for Ag NPs. The existence of various functional groups existing in biomolecules capping the nanoparticles is indicated by the FTIR spectrum. The average size of Ag NPs is 20–35 nm, while the shape is spherical, as confirmed by FESEM. The plant extract and Ag NPs were evaluated against their antioxidant, antibacterial (Staphylococcus aureus, E. coli, and Salmonella typhi), and antifungal activities (Trichophyton longifusis, Candida albican, and Fusarium solani), where the Ag NPs exhibited superior activity versus the plant extract. The inhibitory effect of NPs against the tested strain was more effective as compared to the crude extract of R. stricta.

Linear and nonlinear properties of obliquely propagating waves are studied in a degenerate dense cold magnetoplasma, comprising of Thomas–Fermi distributed electrons and ions as well as non-degenerate negatively charged dust particulates. By using the plane wave approximation, a linear dispersion relation for the dust-cyclotron (DC) and dust-acoustic (DA) waves is derived and analyzed numerically. For fully nonlinear waves, a Sagdeev pseudopotential theory is employed to derive an energy-balance equation and the soliton existence domain depending upon the dust concentration $(h)$ , obliqueness $(L_{z})$ , and Mach number $(M)$ . Numerical analysis reveals that the parameter $h$ enhances the domain for allowed Mach numbers, i.e., $M_{1} and therefore favoring the solitary excitations, where $M_{1}$ and $M_{2}$ are the lower and upper Mach numbers, respectively. In addition, the dust concentration significantly reduces the amplitude and the profile sharpness of the solitary pulses. Similarly, variations in the obliqueness parameter and the Mach numbers modify the wave characteristics. This paper is important for understanding the nonlinear properties of electrostatic excitations in degenerate dusty magnetoplasma, relevant to white dwarfs (WDs), namely $GD56,\,\,GD29-38,\,\,GD362$ , and $WD2115-560$ , being termed as the DUSTY DAZ WDs.

This study involves the preparation and utilization of Al-based catalysts for the photo-catalytic degradation of acridine orange (AO) dye. Al–Sr and Al–Cd were developed in metal oxides nanoparticles and layered double hydroxides (LDH) morphology respectively. The LDH nature of Al–Cd catalyst was confirmed via X-ray diffraction (XRD) spectrum with the characteristic peak at 2θ =11.8o. Sheet like morphology was adopted by both the catalysts as analyzed through field emission scanning electron microscope. The Al–Cd-LDH sheets were assembled above each other. The crystal phase and functional groups of the catalysts were studied through XRD and Fourier transformed infrared spectroscopy respectively. The thermo gravimetric analysis showed the greater stability for Al–Cd-LDH as compared to Al–Sr metal oxides. A band gap of 2.85 eV and 2.6 eV was calculated for Al–Sr metal oxides and Al–Cd-LDH respectively by utilizing diffuse reflectance spectroscopy. The Nitrogen adsorption/desorption isotherms indicated 62.83 m2/g surface area for Al–Cd-LDH and 24.63 m2/g for Al–Sr metal oxides. Similarly, the total pore volume and average pore sizes were 0.933 mL/g and 0.9685 nm for Al–Cd-LDH and 0.0437 mL/g and 1.0393 nm for Al–Sr metal oxides. Both catalysts showed prominent and effective results for the degradation of AO dye. Under UV–Vis light irradiation, the Al–Sr metal oxides showed approximately 90% degradation in 90 min, while Al–Cd-LDH showed less than 50% efficiency. However, with the increase of irradiation time, the degradation rate of Al–Cd-LDH was enhanced to approximately 90% after 240 min. The Al–Cd-LDH showed 29% of acridine orange dye adsorption after 240 min while Al–Sr metal oxides showed 26% adsorption after 90 min. The low catalytic performance of Al–Cd-LDH could be attributed towards the LDH nature which probably interfered the electronic moments for free radical formation. Furthermore, the effect of various parameters such as dye concentration, pH, catalyst amount and different scavengers were also evaluated. Both catalysts showed good recyclability and hence better stability.

Phase diagram provides valuable information to describe the phase and aggregation behavior of surfactants. In this study, surface adsorption behavior of benzyl dimethyl hexadecyl ammonium bromide (BDHAB) surfactant in water and their phase formations have been explored. The formation of lyotropic liquid crystalline (LLC) phases in the binary surfactant–water system was analyzed by polarized light microscopy (PLM). A comprehensive phase diagram was established presenting the existence of LLC phases as a function of surfactant concentration and temperature. The observed PLM images reveal that the BDHAB–H2O system exhibits isotropic (L1), hexagonal liquid crystalline (H1), cubic (V1), and lamellar (L∞) phases in a sequential pattern with the increase of surfactant concentration. The recorded LLC phases for bi-tail BDHAB–H2O system have also been compared with the phase diagram of single tail cetyl trimethyl ammonium bromide (CTAB)–H2O system. The present study evidence that the surfactant morphology (i.e., alkyl chain length and surfactant head-group area) has a significant influence on the formation of micellar aggregates. In addition, surface tension measurements were also performed to observe the surface adsorption behavior of BDHAB surfactant. This study will be beneficial in understanding the micelle formation and solubilization behavior of bi-tailed quaternary ammonium cationic surfactants to optimize its colloidal formulations.

In this paper, we have reported plant mediated green synthesis of copper oxide nanoparticles (CuO NPs) which were further fabricated into mixed matrices of polyether sulfone (PES) and cellulose acetate (CA) by using solution casting technique. Assessment of selected parameters of the synthesized membranes included contact angle, salt rejection, flux behavior and tensile strength measurements. Bovine serum albumin (BSA) rejection measurement of PES-CA-CuO (I), Cu@PES-CA (II), Cu@PES-CA-CuO-1 (III) and Cu@PES-CA-CuO-2 (IV) were absolutely examined. Permeability of I was 65 L h−1 m−2 bar−1 while after growing Cu nanoparticles on the surface of PES-CA-CuO, permeability of III and IV observed was 110 and 85 L h−1 m−2 bar−1 respectively while porosity also exhibited a similar trend. BSA rejection also increased for III and IV respectively in comparison of I. The synthesized materials I–IV were screened out for the catalytic reduction of nitrophenols and IV showed a superior performance. E. coli, a model gram-negative bacterium was used in this study for investigating the antimicrobial activity of the afore-mentioned membranes with III and IV exhibited more than 75% inhibition.

In this study, dense La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) electrodes decorated with the novel hetero-structured ceramic oxide mixture in four different ratios of Ce0.8Gd0.2O2-δ (GDC) and La2Mo2O9 (LMO). The time-dependent conductivity transients were acquire using electrical conductivity relaxation (ECR) technique at a chosen conditions of temperature in the range of 650–850 °C and instantaneous pO2 step change between 0.2 and 0.8. Fitting of time-dependent conductivity to the appropriate non-equilibrium solutions of Fick's diffusion equation has yielded the chemical diffusion coefficient, Dchem, and oxygen surface exchange coefficient, kchem. As expected, the Dchem of the coated samples remained invariant, whilst the kchem is found to vary with the change in GDC-LMO coating mixture ratio. Substantial increase of a factor of 10 in the surface exchange coefficient is noticed for the LSCF coated with a 1:0.75 mixing ratio as compared to bare sample at 850 °C. The enhancement in kchem is attributed to the optimal triple-phase boundary (TPB) regions which promotes oxygen surface exchange kinetics. Thus, coating of selective ratio of hetero-structured oxide in a form of nano-particulate layer over the LSCF surface is considered to be a promising candidate for solid oxide fuel cell (SOFC) cathode.

An efficient, simple, environment-friendly and inexpensive cupric oxide (CuO) electrocatalyst for oxygen evolution reaction (OER) is demonstrated. CuO is chemically deposited on the porous carbon material obtained from the dehydration of common sugar. The morphology of CuO on the porous carbon material is plate-like and monoclinic crystalline phase is confirmed by powder X-ray diffraction. The OER activity of CuO nanostructures is investigated in 1 M KOH aqueous solution. To date, the proposed electrocatalyst has the lowest possible potential of 1.49 V versus RHE (reversible hydrogen electrode) to achieve a current density of 20 mA/cm2 among the CuO based electrocatalysts and has Tafel slope of 115 mV dec-1. The electrocatalyst exhibits an excellent long-term stability for 6 hours along with significant durability. The enhanced catalytic active centers of CuO on the carbon material are due to the porous structure of carbon as well as strong coupling between CuO–C. The functionalization of metal oxides or other related nanostructured materials on porous carbon obtained from common sugar provides an opportunity for the development of efficient energy conversion and energy storage systems.

Lanthanum manganites are being constantly investigated for their interesting magnetic and transport properties. In this study, polycrystalline, single phase lanthanum manganite (LaMnO3) nanofibers were synthesized using an electrospinning technique, and characterized in terms of phase, microstructure, ac and dc electrical properties. X-ray diffraction and scanning electron microscopy revealed the formation of uniform composite nanofibers (average dia.∼ 600 nm) at 100 °C and polycrystalline single phase porous LaMnO3 nanofibers (average dia.∼ 400 nm) when calcined at 600 °C. Temperature dependent impedance and current-voltage (IV) characteristics of LaMnO3 nanofibers deposited on an interdigitated electrode type device, were investigated at temperatures ranging from 298 to 378 K. The observed decrease in the dielectric constant at high frequencies may be due to decrease in the contribution from dipolar polarization. Analysis of ac conductivity indicated thermally activated type conduction mechanism in these nanofibers which could be explained by a correlated barrier hopping (CBH) model. The observed decreasing trend in activation energy with increasing frequency also supported the CBH model. Furthermore, the analysis of log (J) vs. E0.5 curves at different temperatures showed a large difference of ~5.82 between the experimental and theoretical field lowering coefficient with an internal field enhancement factor of α2 = 33.91. This result excluded the possibility of Pool-Frenkel type conduction and the observed variation might be due to the presence of some localized electric fields. Further investigation of IV characteristics revealed that the ‘space-charge-limited current (SCLC) with traps’ may be the possible conduction mechanism.

The deployment of traditional radioactive isotopes as tracers has the drawback of environmental concerns. In this study, we investigated alternative luminescent zinc oxide quantum dots embedded silica (ZnO@SiO2) nanoparticles as tracers for oil reservoir applications. ZnO quantum dots (QDs) were prepared via solgel process having an average diameter of ~5 nm. For the encapsulation of these ZnO QDs, tetraethyl orthosilicate (TEOS) was utilized to synthesize hydrophilic ZnO@SiO2 nanoparticles (H-NPs), while dimethyldiethoxysilane (DMDES) in combination with TEOS was used to prepare partially hydrophobic ZnO@SiO2 (PH-NPs). The fluorescence of bare ZnO QDs was compared to that of silica-coated ZnO@SiO2 NPs in various solvents. The effects of cetyltrimethylammonium bromide (CTAB) surfactant and silica coatings on the fluorescence of ZnO QDs were investigated by photoluminescence spectroscopy. The fluorescence and structural properties of ZnO@SiO2 nano-tracers were examined in highly saline water and at elevated temperature to mimic the oil reservoir environment. The significant improvement in fluorescence emission stability was achieved for PH-NPs in harsh conditions, which advocates their potential use as a tracer material for oil exploration.

Surfactant interactions, self-association, and self-organizing properties can play an important role in customizing colloidal particles surface. Colloidal silica (CS) is an essential biocompatible material, which makes it a suitable candidate for various studies related to surface modifications. In this work, colloidal silica (SiO2) was synthesized using a modified Stober's process. Point of zero charge (PZC) was measured by standard pH titrations. Field emission scanning electron microscopy (FE-SEM) was employed to examine the particle's morphology while phase integrity was confirmed using powder X-rays diffraction (XRD) technique. CS interactions with a cationic dye “methylene blue” (MB) and anionic dye “congo red” (CR) were investigated spectrophotometrically. Later on, CS was modified using cetyltrimethylammonium bromide (CTAB) and observed the changes in PZC and surface morphology, zeta potential and hydrodynamic diameter. The interactions of CTAB modified particles with MB and CR were reinvestigated. For both modified colloidal SiO2 (MCS) and unmodified colloidal SiO2 (CS), different models of adsorption and adsorption kinetics were applied to the UV–Vis spectroscopic data to quantify binding interactions, adsorption efficiency, changes in enthalpy (ΔH), entropy (ΔS), and free energy (ΔG) of the adsorption processes. CS has shown efficient adsorption of MB while MCS was found as a good adsorbent for CR. CTAB enabled the modification of an “anionic surface” of CS to an efficient “cationic surface” and this was demonstrated by significant absorption of an anionic dye CR on the CS surface as well as by the changes in zeta potential and hydrodynamic radius of particles before and after modifications by CTAB.

In this report, we used facile, active, cheap, re-usable and high surface area catalyst for the synthesis of green substrate turmeric (Curcuma longa) powder support mixed silver copper (Ag–Cu/TP), copper nickel (Cu–Ni/TP) and nickel silver (Ni–Ag/TP) nanoparticles. For nanoparticles synthesis the turmeric powder were kept in 0.5 M aqueous metal salt solution and then treated with aqueous solution of NaBH4 for in situ conversion of metal ions into their nanoparticles. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM) and Energy dispersive X-ray spectroscopy (EDX) confirm the formation of nanomaterials. Silver mix nanoparticles show excellent activities against Escherichia coli (E. coli). The prepared nanoparticles were employed for the reduction of fluoroquinolone antibiotics ciprofloxacin (CIP) and levofloxacin (LVO) as well as for Methyl orange (MO), Congo red (CR), Methylene blue (MB) and Rhodamine B (RhB) dyes. Ag–Cu/TP catalyst showed excellent catalytic activity for the reductive transformation of antibiotics as well as for the remediation of MO, CR, MB and RhB dyes. The rate constants of pseudo first order reaction for CIP and LVO were 1.27 × 10−3 s−1 and 1.52 × 10−3 s−1 respectively. Ag–Cu/TP also showed excellent recyclability till the 5th cycle for MO reduction. The abundant nature, low cost, excellent reusability and effective catalytic degradation make Ag–Cu/TP suitable candidates for the reduction of organic molecules.

We report the synthesis of magnetite (Fe3O4) and polyvinylpyrrolidone (PVP) coated Fe3O4 nanoparticles by chemical co-precipitation route. X-ray diffraction (XRD) and transmission electron microscope (TEM) confirm the formation of inverse spinel structure of Fe3O4. XRD peaks of PVP coated Fe3O4 nanoparticles are broad and noisy as compared to Fe3O4. The broadness of peaks is due to small size and large defect density confirmed by energy dispersive spectroscopy (EDS) and scattered area electron diffraction (SAED). Noisy behavior is due to presence of PVP. Average particle size reduced from 10.36 ± 1.97 to 6.91 ± 1.89 nm for Fe3O4 and PVP coated Fe3O4, respectively. From EDS analysis, it is confirmed that the oxygen content reduced from 33.45 to 15.30 at.% with PVP coating. The oxygen content is reduced to half in case of PVP coated Fe3O4 as compared to uncoated Fe3O4. The reduction in oxygen content reveals enhancement in oxygen vacancies. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) confirm the PVP coating and the calculated value of thickness of the PVP layer on the surface of Fe3O4 is 2.4601 nm. Dielectric constant (er) and dielectric loss (tanδ) exhibits the dispersion behavior. Ac conductivity (σac) increases sharply at large frequencies, which is due to enhancement in charge density (liberated charge carriers from defects + conduction charge carriers). The variation in dielectric properties and conductivity is due to Maxwell Wagner interfacial polarization and hopping of charge carriers between Fe2+/Fe3+. Magnetic properties M(T) shows reduction of blocking temperature (TB) from 86 to 75 K for uncoated and PVP coated Fe3O4 nanoparticles. Shifting of TB to lower values is consistent with particle size reduction. M(H) loops at room temperature show typical superparamagnetic behavior. Reduction in saturation magnetization (Ms) is due to the presence of nonmagnetic polymer layer on the surface of Fe3O4 nanoparticles and large number of defects (oxygen vacancies). Field cooled M(H) loops at 5 K show the antisymmetric shift of coercive field along the negative x-axis. The exchange bias field HE enhances to 227 Oe in case of PVP coated Fe3O4 nanoparticles, which is double of the 125 Oe for uncoated nanoparticles. The enhancement in HE is due to smaller sized nanoparticles having large surface to volume ratio having large defect density (oxygen vacancies).

The lid and flap domains control the catalytic activity of lipase through the opening and closing motion. However, this gating mechanism of diacylglycerol (DAG) lipase is poorly understood due to the lack of 3D structures in open conformations. In this study, the opening and closing states of Mrlip1 DAG lipase are revealed by the homology modelling and molecular dynamic simulations. It was found that the active residues (Ser171, His281 and Asp228) in the catalytic pocket of Mrlip1 DAG lipase are covered by the lid domain in the closed conformation, and exposed to the solvent in the open conformation. The role of residues Phe278 and Gln282 in the flap domain, as well as that of Thr101 and Thr107 in the lid domains are also identified in gating mechanism. The site-directed mutagenesis have been carried out to illustrate the putative alterations of enzyme specificity. Our results suggest that the substrate specificity is achieved by these two key residues Phe278 and Gln282, and the irreversible conversion from DAG to TAG (Triacylglycerol) lipase are enabled by the two-point mutations.

The non-magnetic and magnetic polymorphs of iron oxide (Fe2O3) namely: alpha-Fe2O3 (hematite) and gamma-Fe2O3 (maghemite) respectively, were synthesized by a facile surfactant aided hydrogel route. The synthesized polymorphs were characterized by diffuse reflectance, photoluminescence and raman spectroscopy for optical properties whereas the morphological, structural, chemical and electronic state evaluation were performed by FESEM, HRTEM, XRD, and XPS. The charge transport and the stability of the materials were examined electrochemically. The photocatalytic activity of the synthesized polymorphs was evaluated for the degradation of 2-chlorophenol and 2-nitrophenol in the exposure of the visible region and complete spectrum natural sunlight. Both the polymorphs exhibited a significantly high activity for the degradation of the phenolic substrate in the exposure of the complete spectrum of sunlight, however, the activity in the visible region of the sunlight was relatively lower. A substantial increase in the activity in the visible region was noticed when the polymorphs were exposed to complete spectrum sunlight prior to the photocatalytic experiments. The comparison of the exposed and unexposed samples revealed the induction of defects that served as traps for the excited electrons and increased activity of the polymorphs. (C) 2018 Elsevier B.V. All rights reserved.

In this work, two tissue equivalent dosimeters i.e. LiF: Mg, Ti and LiF: Mg, Dy with the same concentration of Mg were synthesized by a chemical co-precipitation method. The crystallite size determined using Sherrer's formula ranged from 30 nm to 35 nm. The absorbance spectra revealed the presence of stretching vibrations of oxides of titanium and dysprosium in LiF: Mg, Ti, and LiF: Mg, Dy, in which oxygen was attached with Ti4+ and Dy3+ cations, respectively. LiF: Mg, Ti exhibited 5 thermoluminescent (TL) peaks corresponding to the multi-trap multi-recombination module with trap depths ranging from 2.052 to 2.89 eV. In LiF: Mg, Dy, only one TL peak was observed corresponding to one-trap and one-recombination module with a trap depth ranging from 2.0318 to 2.5489 eV. The dosimetric peaks of LiF: Mg, Ti occurred in the temperature range 240–260 °C (peak 4) and 280–290 °C (peak 5) with a maximum fading of 2.7% in 108 h. The single dosimetric peak of LiF: Mg, Dy occurred in the temperature range l20–220 °C with a maximum fading of 4.9% for the same duration. The minimum detected dose in LiF: Mg, Ti was 10 mSv with a calibration factor of 0.08882, while in LiF: Mg, Dy, the minimum detected dose was 40 mSv with a calibration factor of 0.34129. Ti-based dosimeter was found to have a linear response in the range of 10 – 10,000 mSv, while, Dy-based dosimeter responded linearly in the dose range of 40 – 10,000 mSv. The latter dosimeter was found to be 3 time less sensitive than the former; therefore, for personal and extremity dosimetry, the former dosimeter appeared more suitable; while for high doses, the latter dosimeter responded well.

Nickel oxide nanofibers were synthesized using an electrospinning technique. X-ray diffraction revealed the formation of single phase polycrystalline NiO nanofibers when calcined at 600 °C. Scanning electron microscopy demonstrated that the average diameter of composite nanofibers dried at 100 °C was ∼400 nm, which decreased to ∼100 nm for samples calcined at 600 °C. The smooth surface of these nanofibers turned highly porous upon burning of the remnant organic constituents (e.g., PVP, acetic acid and other volatile components) and crystallization of the nanofibers upon calcination at 600 °C. At higher voltages, the IV curves followed the bulk limited Poole Frenkel (PF) conduction mechanism. The theoretical field lowering coefficient β Th was in good agreement with the experimental Poole Frenkel field lowering coefficient β PF . The variation in field lowering coefficient may be attributed to the presence of localized electric field due to difference in the work function of NiO nanofibers and electrode material.

Within the framework of kinetic theory, the nonlinear interaction of electromagnetic waves (EMWs) with a degenerate electron-ion plasma is studied to account for the electron quantum mechanical effects. For this purpose, a specific quantum regime is considered, for which the degenerate electron Fermi velocity is assumed to be of the order of the group velocity of EMWs. This eventually leads to the existence of a nonlinear Landau damping rate for the EMWs in the presence of electron ponderomotive force. The electron–ion density oscillations may have arisen from the nonlinear interaction of EMWs, leading to a new type of nonlinear Schrödinger equation in terms of a complex amplitude for electromagnetic pump waves. The profiles of nonlinear damping rates reveal that EMWs become less damped for increasing the quantum tunneling effects. The electrostatic response of the linear electrostatic waves is also investigated and derived from a linear dispersion for the ion-acoustic damping rate. The latter is a direct function of the electron Fermi speed and does not rely on the Bohm tunneling effect. The obtained results are numerically analyzed for two microwaves of different harmonics in the context of nonrelativistic astrophysical dense plasma environments, e.g. white dwarfs, where the electron quantum corrections cannot be ignored.

In the present study, Ce based catalysts were synthesized for the degradation of acridine orange (AO). The Ce-Sr and Ce-Cd oxides were synthesized through sol-gel method and applied for the degradation of acridine orange dye (AO) under visible light influence for environmental remediation. 0.03 mM AO was prepared and 1 g/L of the Ce-Cd and Ce-Sr oxides were applied for degradation of AO. The structure and morphology of the synthesized materials were examined through field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR) and the HOMO and LUMO energy differences were determined through diffuse reflectance spectroscopy (DRS). Both the catalysts were grown in sheet morphology; and the average size of each sheet in Ce-Cd oxide is approximately equal to 790 nm while its average particle size is approximately equal to 20–25 nm, but Ce-Sr oxide average sheet size and particle size were smaller than Ce-Cd oxide. The band gap 2.65 and 2.7 eV for a Ce-Sr and Ce-Cd oxides signifies the high catalytic performance under visible light. The photocatalytic performances of Ce-Cd and Ce-Sr were evaluated against AO dye which resulted 90.2 and 86.6% degradation in 3 h under visible light. These studies showed the high efficiency of Ce based catalysts for environmental remediation.

Nanocomposite membrane (PES-CA-Ag2O) with disinfection properties were developed by inclusion of silver oxide (Ag2O) in polyethersulfone (PES) and cellulose acetate (CA) polymers. Pure PES, CA, PES-CA and nanocomposite membranes were prepared by casting method. Further copper (Cu) nanoparticles were grown on the surface of PES-CA membrane (Cu0@PES-CA) and nanocomposite membrane (Cu0@PES-CA-Ag2O). Structures, compositions and morphologies of all the prepared membranes were confirmed by XRD, FTIR and FESEM techniques. Various properties of PES, CA, PES-CA, PES-CA-Ag2O, Cu0@PES-CA and Cu0@PES-CA-Ag2O were comprehensively studied including water permeation flux, porosity, bovine serum albumin (BSA) rejection, mechanical properties and contact angle measurement. Permeability of the PES-CA and PES-CA-Ag2O was around 63.3 and 92.88 L·h− 1·m− 2 bar− 1 while after growing Cu nanoparticles on the surface of PES-CA and PES-CA-Ag2O, the water permeability reached 72.5 and 100.2 L·h− 1·m− 2 bar− 1. PES-CA-Ag2O and Cu0@PES-CA-Ag2O also showed reasonable porosity. PES-CA-Ag2O and Cu0@PES-CA-Ag2O displayed a marked increase in BSA rejection (88.8 and 89.5, respectively) and the contact angle decreased from 73° to 63.5° and 60.25°, respectively proving the hydrophilic nature of the synthesized materials. Removal of toxic p-nitrophenol from aqueous media is challenging task due to its sorption fouling and tough degradation at lower concentrations. Catalytic reduction capacity of the Cu0@PES-CA and Cu0@PES-CA-Ag2O membranes for different substituted phenols were studied comprehensively Conclusively, unprecedented catalytic potential was observed. Finally, in vitro anti-bacterial activity of the synthesized materials was also investigated against E. coli with promising potential.

This article explores the impact of a magnetic dipole on the heat transfer phenomena of different nano-particles Fe (ferromagnetic) and Fe 3 O 4 (Ferrimagnetic) dispersed in a base fluid ( 60 % water + 40 % ethylene glycol) on micro-polar fluid flow over a stretching sheet. A magnetic dipole in the presence of the ferrities of nano-particles plays an important role in controlling the thermal and momentum boundary layers. The use of magnetic nano-particles is to control the flow and heat transfer process through an external magnetic field. The governing system of partial differential equations is transformed into a system of coupled nonlinear ordinary differential equations by using appropriate similarity variables, and the transformed equations are then solved numerically by using a variational finite element method. The impact of different physical parameters on the velocity, the temperature, the Nusselt number, and the skin friction coefficient is shown. The velocity profile decreases in the order Fe (ferromagnetic fluid) and Fe 3 O 4 (ferrimagnetic fluid). Furthermore, it was observed that the Nusselt number is decreasing with the increasing values of boundary parameter ( &delta, ) , while there is controversy with respect to the increasing values of radiation parameter ( N ) . Additionally, it was observed that the ferromagnetic case gained maximum thermal conductivity, as compared to ferrimagnetic case. In the end, the convergence of the finite element solution was observed, the calculations were found by reducing the mesh size.

Electromagnetic ion cyclotron (EMIC) waves have been studied in this manuscript which are triggered by hot proton thermal anisotropy having energy ranging from 7 to 26 keV with a minimum resonant energy of 6.9 keV. However, an opposite effect can be observed for the hot protons for energy less than the minimum resonant energy. When the intensity of EMIC waves is large, the cold protons (ions) having low-energies can be energized by the EMIC waves. The possible reasons for this energization are the phase bunching of low energy ions with EMIC waves and the generation of electric fields at the relaxation time of substorm. As a consequence, these undetectable protons now become detectable, and the number density and temperature anisotropy of the protons also increase within the energy range from 1 to 100 eV. Accordingly, the helium ions are also energized by the EMIC waves.

A series of La-Sn oxide catalysts were synthesized by facile low temperature hydrothermal procedure. La-Sn oxide nanoparticles were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive spectroscopy (EDS), Fourier transform infrared (FTIR) and UV-visible spectroscopy. The FESEM and XRD analysis revealed the growth of nanoparticles with homogeneous morphology, high crystallinity and particle size of < 20 nm. The synthesized nanoparticles showed excellent catalytic activity for the synthesis of cyclohexanones. The effect of variations in La and Sn contents on the progress of reaction was estimated by yield of the products. The recovery of the catalysts after the completion of reactions was also assessed.

Background: Potable, clean and safe water is the basic need for all human beings. Major portion of the earth is occupied by water, however, this is contaminated by rapid industrialization, improper sewage and natural calamities and man-made activates, which produce several water-borne and fetal diseases. In this review we presented some recent patent for environmental remediation. Methods: Various technologies have been developed for the treatment of waste water consist of chemical, membrane, filtration, sedimentation, chlorination, disinfection, electrodialysis, electrolysis, reverse osmosis and adsorption. Among these entire phenomenon’s, adsorption was the most efficient method for wastewater treatment, because it is a quick and cheap technology which signifies extensive practical applications. Adsorption phenomenon has been tactfully used for the removal of biological waste as well as soluble and insoluble material with a removal efficacy of 90-99%. Results: Clean water supply is limited to human beings. The people in the developing countries have less or no access to the clean and potable water. The shortage of potable water resources and long term safe water deficiencies are some of the leading problems worldwide. In this review, we have explained in the detail adsorption phenomena of chitosan, pharmaceutical importance and other applications. It is worth to say that adsorption technologies using chitosan and its derivative is one of the quickest and cost effective methods for the wastewater treatment. The review comprises of ninety eight references. This review also covers various patents vis-a-vis the role of chitosan-nanocomposite in environmental application for wastewater treatment. Conclusion: Chitosan is a pseudo-neutral cationic polymer which is formed by the de-acetylation of chitin polymer. Various patent on chitosan and chitosan-nanocomposite were taken into account related to wastewater purification. We have found that chitosan and chitosan-nanocomposite are used for the removal of viruses, bacteria, cryptosporidium oocysts and giardia cysts, soluble and insoluble organic pollutants, poly aromatic hydrocarbons and heavy metals from wastewater. In this study, we also found that chitosan and chitosan-nanocomposite are selected for the removal of transition metals.

Two dimensional (2D) nanomaterials have interesting properties due to their lateral dimensions. Pure self-assembled l -cysteine stabilized covellite nanoplates (CuS@L-Cys NPs) and l -cysteine stabilized chalcocite nano leaves (Cu2S@L-Cys NLs) were synthesized by using a template free, the facile hydrothermal route with the best control of size, phase purity structure, morphology, and electrochemical properties. Novel CuS@L-Cys NPs and Cu2S@L-Cys NLs snowflakes dendrites were synthesized by varying synthetic parameters such as solvent, temperature (100–180 °C), reaction time (8–24 h), pH of reaction medium (7–14), the concentration of base (0.1–2.4 mL NH3) and concentration of thiourea (1–4 mmol). By changing these factors, different morphologies such as irregular, regular, trigonal, hexagonal leaf and snowflakes dendrites like shapes were observed. CuS@L-Cys NPs and Cu2S@L-Cys NLs were fabricated by using water and ethylenediamine (EDA) as solvent respectively. CuS@L-Cys NPs and Cu2S@L-Cys NLs were investigated for potential photocatalytic applications in methyl orange (MO) degradation under visible light with a detailed mechanism. The noteworthy, unique bandgap of 2 eV and the special morphology of CuS@L-Cys NPs increases the active sites for adsorption of dye, which causes extraordinary degradation activity. Furthermore, the l -cysteine (L-Cys) protective layer could efficiently alleviate the photocorrosion of CuS and Cu2S, giving rise to excellent stability.

Bismuth borate glasses containing lithium and gadolinium were doped with (0.1–2.5 mol%) of Ce and their optical and radiation response were investigated. These modified glasses exhibited photoluminescent properties in response to the radiations, which were evidenced by their broad-band spectral features around 378 nm due to 5d→4f transitions of the Ce3+ ions. The intensity response of these glasses increased with increasing concentration of cerium up to 2.0 mol% which decreased upon further increase in the concentration of cerium due to the quenching effect and cross-relaxation between the nearest ions. Gamma irradiation of samples with 1 and 2 Gy doses demonstrated an increase in the intensity of photoluminescence peaks with increase in the irradiation dose. The observed increase caused the formation of relatively more electron and hole trap centers that eventually led to more recombinations in the glass matrix. This enhancement in the intensity after irradiation was also proportional to the dose as expected and the photoluminescence peaks observed for the irradiation samples were broader than those of un-irradiated samples. The observed decrease in intensity after irradiation of samples with high cerium concentration (i.e. 2.5 mol%) may be linked to the energy transfer and dissipation occurring during cross-relaxation among the nearest cerium ions.