Straightforward Synthesis of Mn3O4/ZnO/Eu2O3-Based Ternary Heterostructure Nano-Photocatalyst and Its Application for the Photodegradation of Methyl Orange and Methylene Blue Dyes

Zinc oxide-ternary heterostructure Mn₃O₄/ZnO/Eu₂O₃ nanocomposites were successfully prepared via waste curd as fuel by a facile one-pot combustion procedure. The fabricated heterostructures were characterized utilizing XRD, UV–Visible, FT-IR, FE-SEM, HRTEM and EDX analysis. The photocatalytic degradation efficacy of the synthesized ternary nanocomposite was evaluated utilizing model organic pollutants of methylene blue (MB) and methyl orange (MO) in water as examples of cationic dyes and anionic dyes, respectively, under natural solar irradiation. The effect of various experimental factors, viz. the effect of a light source, catalyst dosage, irradiation time, pH of dye solution and dye concentration on the photodegradation activity, was systematically studied. The ternary Mn₃O₄/ZnO/Eu₂O₃ photocatalyst exhibited excellent MB and MO degradation activity of 98% and 96%, respectively, at 150 min under natural sunlight irradiation. Experiments further conclude that the fabricated nanocomposite exhibits pH-dependent photocatalytic efficacy, and for best results, concentrations of dye and catalysts have to be maintained in a specific range. The prepared photocatalysts are exemplary and could be employed for wastewater handling and several ecological applications.     

Synthesis of core‐shell magnetic molecularly imprinted polymer for the selective determination of imidacloprid in apple samples

This work demonstrates the synthesis and characterization of core‐shell magnetic molecularly imprinted polymers based on surface imprinting using methacryloyl chloride as a functional monomer for the selective extraction of imidacloprid (template) from apple fruit. The characterization analysis results ensured the successful synthesis of the magnetic molecularly imprinted polymers owing to their heterogeneous structure and good magnetic properties. An isothermal binding test was assessed with a pseudo‐second‐order kinetic model, and the kinetic results fit well to the Freundlich isothermal model. The polymers exhibited an adsorption capacity of 5.75 mg/g for the target analyte with a good selective extraction ability. In addition, the polymers can be reused several times without significant performance loss. The molecularly imprinted polymers showed good performance in the analysis of spiked apple sample with a linear range of 0.05–1.0 mg/L, a limit of detection of 0.048 mg/L and a limit of quantification of 0.146 mg/L (S/N = 3/10). The recoveries of the samples were 77.66–96.57% and their respective relative standard deviations were 3.36–0.45%. All the results indicated that the proposed method provided good selective extraction, as qualifying the analytical standards.     

Synthesis of Novel Symmetric Porphyrin Schiff Base Dimers by Solid–Liquid Reaction Methodology

A new convenient solid–liquid condensation reaction procedure for the synthesis of novel asymmetric and symmetric meso‐tetraarylporphyrin and metalloporphyrin Schiff bases is reported. The condensation reaction between β‐formyl porphyrin or metalloporphyrins and aromatic amines was carried out at solid–liquid interface by using neutral alumina powder as a solid support for β‐formyl porphyrin or metalloporphyrins and absolute ethanol as the carrier solvent for aromatic amines. Six different asymmetric porphyrin/metalloporphyrin Schiff bases were synthesized via solid–liquid interface reaction methodology. The same solid–liquid synthetic methodology was applied for the synthesis of six novel symmetric Schiff base porphyrin/metalloporphyrin dimers. The comparison of UV–visible spectra of porphyrin Schiff base monomers and dimers revealed that some degree of electronic perturbation has occurred upon dimerization as the Soret bands of the monomers underwent peak broadening along with red shifts. Column chromatography and crystallization were used to purify the compounds. Fourier transform infrared, UV–visible, elemental analysis, ¹H NMR, and mass spectrometry were used to characterize the newly synthesized compounds.     

CT/MRI‐Guided Synergistic Radiotherapy and X‐ray Inducible Photodynamic Therapy Using Tb‐Doped Gd‐W‐Nanoscintillators

The use of X‐rays instead of UV/Vis light to trigger photodynamic therapy, named X‐ray inducible photodynamic therapy, holds tremendous promise due to a high penetration capacity in tissues and is worthy of in‐depth study. In this study, a novel multifunctional nanoagent based on Merocyanine 540‐coupled Gd₂(WO₄)₃:Tb nanoscintillators and the vitalization of its abilities for dual‐modal computed tomography and the magnetic‐resonance‐imaging‐guided synergistic radio‐/X‐ray inducible photodynamic therapy of tumors is reported. Synergistic therapies show a higher tumor growth inhibition efficiency at a lower X‐ray dose than radiotherapy alone. Through this proof‐of‐concept work, a way to tactfully understand and utilize nanoscintillators for cancer theranostics is shown.     

Kinetic treatment of acoustic waves in a four‐component dusty plasma

A kinetic formulation is developed to investigate low‐frequency dust ion acoustic waves (DIAWs) and dust acoustic waves (DAWs) as well as numerically for a four‐component, collisionless, unmagnetized dusty plasma, using the linearized Vlasov–Poisson model for species obeying the Maxwellian distribution. In particular, the dynamics of low‐frequency DIAWs is investigated by considering two cases. In the first case, ions and positive dust particles are assumed to be dynamically adiabatic while the negative dust particles are static in the background. In second case, the ions are taken adiabatic, while both positive and negative dust particles are static in the background. For DAWs, the ions are assumed to be isothermal, while both positive and negative dust species are considered adiabatic. Electrons are assumed to be isothermal in all cases. The linear characteristics and Landau damping rates for DIAWs and DAWs are investigated with effects of the dust particle concentrations and different temperature ratios. It is noted that for higher values of positive dust concentration, DIAWs (DAWs) are less (more) damped. It is also observed that the damping rate increases (decreases) as T_i approaches T_e for DIAWs (DAWs). It is worth adding here that the theoretical results presented here are supported by numerical analyses and illustrations. The relevance of the study to laboratory and cosmic plasmas is also pointed out.     

Wormholes supported by phantom-like modified Chaplygin gas

We have examined the possible construction of a stationary, spherically symmetric and spatially inhomogeneous wormhole spacetime supported by the phantom energy. The latter is supposed to be represented by the modified Chaplygin gas equation of state. The solutions so obtained satisfy the flare-out and the asymptotic-flatness conditions. It is also shown that the averaged null-energy condition has to be violated for the existence of the wormhole.     

An experimental and computational study of methyl ester decomposition pathways using shock tubes

The high-temperature decomposition of three simple methyl esters: methyl acetate, methyl propionate and methyl butanoate, were studied behind reflected shock waves using tunable diode laser absorption of CO₂ near 2.7 μm. CO₂ yield measurements were made over the range of temperatures 1260-1653 K, pressures of 1.4-1.7 atm and reactant concentrations of 2-3%, with the balance Ar. The CO₂ absorption strengths near 2.7 μm are approximately 50 to 1000 times stronger than the bands near 2.0 and 1.55 μm, respectively, and offer opportunities for significantly more sensitive and accurate combustion measurements than previous absorption work using CO₂ bands at shorter wavelength. The experiments provide the first laser-based time-history measurements of the CO₂ yields during pyrolysis of these bio-diesel surrogate fuels in a shock tube. Model predictions for CO₂ yields during methyl butanoate pyrolysis at high temperatures, using the detailed reaction mechanisms of [E. M. Fisher, W. J. Pitz, H. J. Curran, C. K. Westbrook, Proc. Combust. Inst. 28 (2000) 1579-1586.] and others, are significantly lower than those measured in this study. However, an improved methyl butanoate model which extends the recent theoretical work of [L.K. Huynh, A. Violi, J. Org. Chem. 73 (2008) 94-101.] provides substantially improved predictions of CO₂ yields during methyl butanoate pyrolysis. As earlier mechanisms predicted low yields of CO₂ from methyl butanoate decomposition, these new findings imply that existing bio-diesel fuel models, which rely on the rapid formation of two oxygenate radicals from methyl esters (rather than a single non-reactive CO₂ molecule) to account for the tendency for soot reduction, may have to be revisited.     

An IH-QCL based gas sensor for simultaneous detection of methane and acetylene

Extended wavelength tuning of an IH-QCL (integrated heater quantum cascade laser) is exploited for simultaneous detection of methane and acetylene using direct absorption spectroscopy. The integrated heater, placed within few microns of the laser active region, enables wider wavelength tuning than would be possible with a conventional DFB (distributed feedback) QCL. In this work, the laser current and heater resistor current are modulated simultaneously at 25?kHz to tune the laser over 1279.6–1280.1 cm^?1, covering absorption transitions of methane and acetylene. The laser is characterized extensively to understand the dependence of wavelength tuning on modulation frequency, modulation amplitude and phase difference between laser/heater modulation. Thereafter, the designed sensor is validated in both room-temperature static cell experiments and non-reactive high-temperature-measurements in methane-acetylene-argon gas mixtures in the shock tube. Finally, the sensor is applied for simultaneous detection of methane and acetylene during the high-temperature pyrolysis of iso-octane behind reflected shock waves.     

Synthesis and electrochemical characterization of graphene nanoflakes and LiFe<Subscript>0.97</Subscript>Ni<Subscript>0.03</Subscript>PO<Subscript>4</Subscript>/C for lithium-ion battery

The graphene nanoflakes and olivine-type LiFe_0.97Ni_0.03PO₄/C (LFNP3/C) samples have been synthesized as anode and cathode materials, respectively. Physicochemical characterization of the graphene nanoflakes and LFNP3/C material were studied using X-ray diffraction (XRD) and scanning electron microscope (SEM). The XRD patterns reveal the formation of the pure phase of both the synthesized samples. SEM micrographs disclose the formation of spherically shaped nanosized particles for LFNP3/C while graphene shows flake-type morphology. CR2032 half and full coin cells were assembled for electrochemical testing of the synthesized samples. Cyclic voltammetry (CV) results indicate that the graphene-based half-cells, i.e., GN1H and GN2H, possess reduction peak/plateau around 0.17 V while LFNP3/C cathode shows discharging voltage plateau at 3.4 V vs. Li/Li⁺. The discharge capacities were found to be 700, 900, and 153 mAhg^?1 for GN1H, GN2H, and LFNP3/C half-cells vs. Li/Li⁺, respectively. Among full cells, LFPGN1F with γ = 0.75 (mass/capacity balancing factor) shows better charging/discharging profile at each C-rate as compared to LFPGN2F with γ = 0.55. LFPGN1F delivered an initial discharge capacity of around 154 mAhg^?1 at 0.1C and even at a high discharge rate of 1C, it retained ~97% of the discharge capacity as compared to the initial cycle at the same rate.