Extraction of cadmium by TODGA–dodecane and TBP–dodecane: A comparative study by MD simulation

Molecular dynamics (MD) simulation of [Cd(II)] along with nitrate ions and water in dodecane was carried out for different nitric acid concentrations. The extraction process using N,N,N’,N’-tetraoctyldiglycolamide (TODGA) and tributyl phosphate (TBP), in biphasic systems, is also simulated at three nitric acid concentrations. In the TBP-based system, the formation of a third phase was observed at 3 M nitric acid concentration. Cd(II) ions form reverse micelles-like clusters with TODGA as an extractant in dodecane. The mass percentage of TODGA in these clusters decreases with increase in the acid concentration while increasing the size of the aggregates at the same time.     

Insight into nitric acid extraction and aggregation of N,N, N’, N’-Tetraoctyl diglycolamide (TODGA) in organic solutions by molecular dynamics simulation

The molecular dynamics (MD) simulation of TODGA in n-dodecane shows formation of nanostructures of TODGA aggregates with nitric acid and water. These aggregates are dispersed in dodecane phase or form well defined reverse micelles grown sufficient in size depending on the acid concentration. With increasing nitric acid concentration, aggregation number of TODGA in reverse micelles also increases which, however, is independent of TODGA concentration. Aggregation number rises from 2 to 8 in presence of 0–3.5 M nitric acid in corresponding aqueous phase. The formation of the aggregates explains remarkable acid co-extraction from aqueous phase to organic dodecane phase by TODGA.     

Natamycin: a natural preservative for food applications—a review

Food Science and Biotechnology - Natamycin is a natural antimicrobial peptide produced by the strains of Streptomyces natalensis. It effectively acts as an antifungal preservative on various food...     

Synthesis of Fe-Si-B-Mn-based nanocrystalline magnetic alloys with large coercivity by high energy ball milling

Alloys of Fe-Si-B with varying compositions of Mn were prepared using high energy planetary ball mill for maximum duration of 120 h. X-ray diffraction (XRD) analysis suggests that Si gets mostly dissolved into Fe after 80 h of milling for all compositions. The residual Si was found to form an intermetallic Fe₃Si. The dissolution was further confirmed from the field emission scanning electron microscopy/energy dispersive X-ray analysis (FE-SEM/EDX). With increased milling time, the lattice parameter and lattice strain are found to increase. However, the crystallite size decreases from micrometer (75–95 μm) to nanometer (10–20 nm). Mössbauer spectra analysis suggests the presence of essentially ferromagnetic phases with small percentage of super paramagnetic phase in the system. The saturation magnetization (M _s), remanance (M _r) and coercivity (H _c) values for Fe-0Mn sample after 120 h of milling were 96.4 Am²/kg, 11.5 Am²/kg and 12.42 k Am^?1, respectively. However, for Fe-10Mn-5Cu sample the M _s, H _c and M _r values were found to be 101.9 Am²/kg, 10.98 kA/m and 12.4 Am²/kg, respectively. The higher value of magnetization could be attributed to the favourable coupling between Mn and Cu.     

Synthesis of Low Coercive BaFe12O19 Hexaferrite for Microwave Applications in Low-Temperature Cofired Ceramic

Polycrystalline M-type barium hexaferrite (BaFe₁₂O₁₉) samples have been synthesized by solution combustion route at different pH and calcination conditions in order to reduce the coercivity for microwave applications in low-temperature cofired ceramic (LTCC) substrates. Structural, morphological, and magnetic properties of BaFe₁₂O₁₉ were studied by x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), Raman spectroscopy, vibrating sample magnetometry (VSM), and Mössbauer spectroscopy. The formation of a single-phase hexagonal structure was confirmed by XRD. The Raman spectra reveal all characteristic peaks of BaFe₁₂O₁₉, illustrating the phase purity and crystal lattice symmetry of the synthesized material. Mössbauer spectra illustrate the existence of Fe³⁺ cations at all five crystallographic lattice sites. The microstructural features observed by FESEM disclose the growth of nanoregime particles into hexagonal platelet particles after calcination at temperatures from 800°C to 1200°C. The VSM results show a lower coercivity (1350 Oe to 3500 Oe) together with reasonably high saturation magnetization (55 emu/g to 60 emu/g) and a high bulk resistivity (>10⁹ Ω-cm) at room temperature. The dependence of magnetic and electrical properties on the preparation and processing conditions is also discussed.     

Evaluation of Models for Spinach Respiratory Metabolism Under Low Oxygen Atmospheres

Anaerobic respiration is a major problem that causes the deterioration of fresh produce packaged under low O₂ atmospheres. The problem becomes more severe and causes high losses in the packages handling at ambient conditions, especially in developing countries. In designing modified atmosphere packaging, the risk of anaerobic development greatly depends upon the accuracy of respiration rate prediction; therefore, the respiration rate model for a particular produce has to be identified. In this study, different atmospheric storage conditions in a closed system were realized to examine the adaptability of respiration rate models for spinach storage under low O₂ at an expected ambient temperature of 25 °C. Six models were applied and it was found that, for aerobic conditions, the respiration rate could be described with a constant respiratory quotient by three models, viz., (a) Michaelis–Menten model without inhibition, (b) Michaelis–Menten model with uncompetitive inhibition, and (c) Langmuir adsorption model, whereas three other models, viz. (d) Michaelis–Menten model with competitive inhibition, (e) Michaelis–Menten model with noncompetitive inhibition, and (f) Michaelis–Menten with mixed inhibition could not be fitted. Among the three successful models, the Michaelis–Menten with uncompetitive inhibition was found to be the most suitable model for practical applications in developing countries where cold-chain systems are lacking. This model can be applied for the prediction of gas composition and optimize the packages, particularly to ensure the aerobic respiration.     

Mechanistic interaction study of thin oxide dielectric with conducting organic electrode

This paper aims at understanding the interaction of intrinsic conducting polymer, PEDT, with ALD-deposited Al₂O₃ and thermally oxidized Ta₂O₅ dielectrics, and the underlying mechanisms for increase in leakage currents in PEDT-based capacitors. Conducting polymers offer several advantages as electrodes for high surface area capacitors because of their lower resistance, self-healing and enhanced conformality. However, capacitors with in situ polymerized PEDT show poor electrical properties that are attributed to the interfacial interaction between the organic electrode and the oxide dielectric. This study focuses on characterizing these interactions. A combination of compositional, structural and electrical characterization techniques was applied to polymer-solid-state-capacitor to understand the interfacial chemical behavior and dielectric property deterioration of alumina and tantalum-oxide films. XPS and impedance studies were employed to understand the stiochiometric and compositional changes that occur in the dielectric film on interaction with in situ deposited PEDT. Based on the observations from several complimentary techniques, it is concluded that tantalum-pentoxide has more resistance towards chemical interaction with in situ polymerized PEDT. The thermally oxidized Ta₂O₅-PEDT system showed leakage current of 280 nA μF⁻¹ at 3 V with a breakdown voltage of 30 V. On the other hand, Al₂O₃-PEDT capacitor showed leakage current of 50 μA μF⁻¹ and a breakdown voltage of 40 V. The study reports direct evidence for the mechanism of resistivity drop in alumina dielectric with in situ polymerized PEDT electrode.     

Fabrication and characterization of novel silicon-compatible high-density capacitors

System integration and miniaturization demands are driving component technologies towards integrated thin films with higher volumetric efficiencies and component densities. Among the various system components, achieving higher densities with capacitors, integrated in thin film form has been a major challenge for the past few decades. This paper reports the first proof-of-concept demonstration of a novel silicon-compatible high-density capacitor technology. The key novelty stems from the tremendous enhancement in surface area from thin and porous copper nanoelectrodes and conformal alumina dielectric on such nanoelectrodes. Atomic Layer Deposition was chosen as the dielectric process because of its self-limiting, defect-free and conformal deposition on 3-D structures. Alumina with its moderate permittivity and superior dielectric properties over large voltage ranges was employed as the representative dielectric. Thin copper particulate electrodes with conformal counter electrodes showed 10 times higher capacitance density compared to the planar devices, with similar leakage properties. Thicker electrodes showed enormous enhancement in surface area but inferior leakage properties. Combination of compositional and morphological techniques was used to show alumina conformality on complex 3-D structures of copper particulate electrode. Capacitance–Voltage and Current–Voltage characterizations were carried out to confirm the feasibility of the novel high density 3-D capacitor structure.