Spinel ferrite nanoparticles are widely studied to evaluate their suitability in many applications. Magnetic, electrical, optical, and catalytic properties of spinel ferrites nanoparticles depend on: ...i) intrinsic property such as cation distribution among tetrahedral (A-site) and octahedral ligand (B-site) sublattices in spinel structure and ii) extrinsic properties such as specific surface area and particle size distribution of nanoparticles. To enhance the above properties by modifying both the intrinsic and extrinsic parameters, narrow size distributed Mg 0.7 Zn 0.3 Fe 2 O 4 mixed spinel ferrite nanoparticles are synthesized by the solvothermal reflux method using high boiling point reflux solvents. The particles are crystallized in a cubic spinel structure and are single crystallites with an average particle diameter of 12 nm, measured from an electron micrograph. The temperature-dependent dielectric constant <inline-formula> <tex-math notation="LaTeX">(\varepsilon^{\prime}) </tex-math></inline-formula> and dielectric loss <inline-formula> <tex-math notation="LaTeX">(\varepsilon^{\prime \prime}) </tex-math></inline-formula> of the sample show no change below 290 °C and increase with temperature up to 450 °C. Both <inline-formula> <tex-math notation="LaTeX">\varepsilon^{\prime} </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">\varepsilon^{\prime} </tex-math></inline-formula> decrease with the increase of electric field frequency and shows dominant space charge polarization at grain boundaries. The DC conductivity estimated from impedance spectra (Cole-Cole plot) shows the Arrhenius model electron hopping conductivity mechanism above 390 °C. Nanoparticles show high Ms (57.41 emu/g) than that synthesized by other methods. The sample shows the magnetic hyperthermia value of 189 W/g at 1 mg/mL concentration. The sample degraded 95% of rhodamine B dye in water in 320 min under UV light illumination. Some of these properties are superior to Mg 0.7 Zn 0.3 Fe 2 O 4 nanoparticles synthesized by other wet chemical and/or ball milling methods.
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•Simple and efficient protocol for sonochemical synthesis of Cu2O nanoparticles.•Additive free, capping agent free synthesis of spherical Cu2O nanoparticles.•Glycerol acts as a ...solvent, reducing and capping agent in a reaction.•Cu2O nanoparticles show excellent catalytic activity in N-arylation of imidazole.
A one step, additive free protocol for ultrasound assisted synthesis of cuprous oxide (Cu2O) nanoparticles using glycerol as a green and sustainable solvent has been developed. The glycerol plays multiple roles in nanoparticle synthesis such as solvent, promoter, reducing agent and capping agent. It assists to control the crystal morphology of obtained Cu2O nanoparticles. The Cu2O nanoparticles were characterized with the help of XRD, TEM, HRTEM, EDS, FT-IR, XPS, BET surface area and TGA techniques. This is simple, green, inexpensive and capping agent free method for the synthesis of Cu2O nanoparticles. Furthermore, we showed catalytic applications of prepared Cu2O nanoparticles in catalysis for the coupling reaction between aryl halide and aromatic amine.
A high performance iron–air rechargeable battery has the potential of meeting the requirements of grid-scale energy storage. When successfully demonstrated, this battery technology can be ...transformational because of the extremely low cost of iron, the extraordinary environmental friendliness of iron and air, and the abundance of raw materials. The key technical challenges that hinder the successful commercialization of the iron–air battery are its efficiency and cycle life. An innovative multi-pronged strategy that aims at raising the round-trip energy efficiency from 50% to 80%, and the cycle life from 2000 to 5000 cycles is therefore necessary to meet the requirements of large scale energy storage.
Calcium-doped lanthanum cobalt oxide is a promising electrocatalyst for oxygen evolution and oxygen reduction in rechargeable metal–air batteries and water electrolyzers operating with alkaline ...electrolyte. Nanocrystalline perovskite of composition La0.6Ca0.4CoO3 with a unique cellular internal structure was prepared at 350 °C and then annealed in air at progressively higher temperatures in the range of 600–750 °C. The samples were characterized by electrochemical techniques and X-ray photoelectron spectroscopy. The area-specific electrocatalytic activity for oxygen evolution/oxygen reduction, the oxidation state of cobalt, and the crystallite size increased with annealing temperature, while the Tafel slope remained constant. These trends provide new insights into the role of the cobalt center in oxygen evolution and oxygen reduction, and how preparation conditions can be altered to tune the activity of the cobalt center for electrocatalysis. We expect these findings to guide the design of electrocatalysts for bifunctional oxygen electrodes, in general.
Biocompatible Mg
Zn
Fe
O
(x=0.2, 0.4, 0.5, 0.6 & 0.8) nanoparticles were synthesized by solvothermal reflux method. All compounds were crystallized in cubic spinel structure with slightly enhance of ...lattice parameter with biocompatible substituent Zn
concentration. All compounds were shown spherical geometry with average particle diameter is around 12nm (colloidal size). The spinel structure formation was confirmed by X-ray diffraction,electron diffraction, infrared, Raman shift measurements. Infrared analysis shows oleic acid coating on the surface of nanoparticles and TGA analysis shows that oleic acid desorbs from nanoparticle by decomposition at around 400°C. UV-Vis-NIR spectra show all the compounds show energy band gap in the semiconductor range (≈ 1.9eV). All compounds show superparamagnetic characteristics at room temperature with enhanced saturated mass magnetization (M
) with Zn
concentration up to x=0.5 and then reduces with further enhance of x up to 0.8. The M
changes were ascribed to occupation of Zn
at tetrahedral sites and proportional enhance of Fe
at octahedral sites. The enhanced Fe
concentration at octahedral sublattice leads to formation Fe
-O
-Fe
networks which favor antiferromagnetic interactions due to superexchange phenomenon. Photocatalytic activity of all compounds were studied through methylene blue (MB) degradation analysis. All compounds show ≈ 96% degradation of MB upon 70min irradiation of light on photoreactor vessel. In addition, photocatalytic activity (degradation efficiency) enhances with Zn
concentration in MgFe
O
. The Zn
substitution enhances both M
and photocatalytic activity biocompatible of MgFe
O
nanoparticles.
We studied the effects of post-growth annealing on InAs sub-monolayer samples with different numbers of quantum dot stacks embedded in InGaAs wells. Four samples, with 4, 6, 8, and 10 dot stacks, ...were grown with solid phase, molecular beam epitaxy under invariant conditions. Increasing the number of stacks created a gradual shift in the photoluminescence ground-state transition energy of the samples from 1.195 to 1.111eV. Subjecting the samples to post-growth thermal annealing at 650, 700, 750, and 800°C produced a typical blue-shift. The full-width-half-maxima of the emission spectrum narrowed with an increase in annealing temperature. All samples exhibited significant enhancement in their activation energies when annealed at 650°C, suggesting that annealing healed defects created during sample growth.
•Sub-monolayer QDs with different numbers of stacks (4, 6, 8 and 10) were compared.•PL spectra showed red-shift with increase in number of stacks.•PL spectra of as-grown samples exhibit rapid decay with increase in temperature.•All four samples were annealed at four different temperatures.•Each sample showed blue-shift upon annealing.•Activation energy was observed first to increase at 650°C and then decreased.
Lithium bromide ionic salt dispersed with poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/polyvinylpyrrolidone (PVP) blend polymers have been prepared by solution casting, and used as an ...electrolyte for the improvement of solid-state lithium batteries. The structural and molecular bond identification studies of polymer electrolytes have been studied and confirmed using x-ray diffraction (XRD) and Fourier-transform (FTIR) analysis. Electrical characterizations of solid polymer films have been studied by AC impedance analysis. The higher conducting sample follows the Arrhenius relationship, and the conductivity based on the dielectric constant obeys modified Arrhenius behavior. The ion transport mechanisms coincide with the correlated barrier height (CBH) model, and the ionic diffusion was verified through the tunneling mechanism. Optical properties for the prepared polymer electrolytes have been investigated using ultra violet (UV) spectrum analysis. From this analysis, the higher conductivity polymer electrolyte has a minimum band gap at 4.14 eV.
Present work reports a new method for one pot synthesis of nanosize cuprous oxide (Cu2O). In this method, the synthesis of nanocrystalline Cu2O was carried out using benzyl alcohol as a solvent and ...copper acetate as a precursor under microwave irradiation. In this protocol, benzyl alcohol played a multiple role such as solvent, reagent and stabiliser eliminating the need of any other extraneous additives. The protocol enables synthesis of nanosize cuprous oxide within a short span of few minutes and without calcinations. The prepared nanosize Cu2O was characterised with the help of X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDS) and UV–vis absorption spectroscopy. The results showed that the size of Cu2O particles was in the nano region. The particles were well crystalline and essentially pure. This is one of the facile and environment friendly protocols for synthesis of nanosize cuprous oxide.
A rapid, calcination free protocol for the synthesis of nanosized cuprous oxide (Cu2O) has been developed by using cuprous acetate and benzyl alcohol under microwave irradiation. Benzyl alcohol acts as a solvent, reactant, stabilizer and fuel. As prepared Cu2O was well studied by different analytical techniques. The result showed Cu2O is in the nano region with a spherical morphology. Display omitted
► Fast and calcinations free synthesis of nanosize Cu2O ► One pot, one step, simple synthesis of nanosize Cu2O via microwave method ► Benzyl alcohol plays roles as reagent, solvent and stabiliser which eliminate the need of any other extraneous additives
Background: The potential harm and clinical benefits of inotropic therapy in patients with decompensated heart failure with reduced ejection fraction or advanced heart failure were debated for three ...decades. Nonetheless, confronted with a dismal quality of life in the last months to years of life, continuous home inotropic therapy has recently gained traction for palliative therapy in patients who are not candidates for left ventricular mechanical circulatory support or heart transplantation. Methods: As continuous inotropic therapy is only considered for patients who experience symptomatic relief and display objective evidence of improvement, clinical equipoise is no longer present, and randomized controlled trials are hard to conduct. Results: We first outline the transient use of inotropic therapy in patients with decompensated heart failure with reduced ejection fraction and emphasize the hemodynamic requisite for inotropic therapy, which is a demonstration of a low cardiac output through a low mixed venous oxygen saturation. Lastly, we review the current experience with the use of home inotropic therapy in patients who are not candidates or are awaiting mechanical circulatory support or heart transplantation. Conclusions: Evidence-based clinical data are needed to guide inotropic therapy for refractory decompensated heart failure with reduced ejection fraction in patients who are ineligible or awaiting mechanical circulatory support or heart transplantation.
