Synthesis and characterisation of starch/agar nanocomposite films for food packaging application

In the present work cassava starch/agar Ag and ZnO nanocomposite films were prepared by the solution casting method. The structural, physical and antimicrobial properties of the nanocomposite films were studied as a function of the concentration of Ag and ZnO nanoparticles. The results of the thermogravimetric analysis showed 8–15% degradation of both the nanocomposite films at 150°C endorsing the thermal stability of the films. Scanning electron microscopic analysis reveals the uniform blending of Ag and ZnO nanoparticles with a starch/agar matrix with tiny waves like appearance on the surface. The incorporation of Ag and ZnO nanoparticles in the film was found to reduce the moisture content, water solubility and water vapour permeability with increase in the concentration of Ag and ZnO nanoparticles. The growth kinetics study of Pseudomonas aeruginosa and Staphylococcus aureus in the presence of Ag and ZnO blended nanocomposite films showed promising results especially against Gram‐negative P. aeruginosa. Thus, the film synthesised in the present study bears the potential to be used as active packaging material to prevent food from bacterial contamination and spoilage.Inspec keywords: casting, microorganisms, scanning electron microscopy, nanoparticles, food preservation, solubility, thermal analysis, zinc compounds, food processing industry, food products, thermal stability, permeability, antibacterial activity, food packaging, contaminationOther keywords: water vapour permeability, food packaging, solution casting method, structural properties, physical properties, antimicrobial properties, water solubility, agar nanocomposite film, starch nanocomposite film, Pseudomonas aeruginosa, Staphylococcus aureus, bacterial contamination prevention, spoilage prevention, scanning electron microscopic analysis, thermogravimetric analysis, temperature 150.0 degC, Ag, ZnO     

Low temperature synthesis,dielectric and electrical characteristics of Bi2/3Cu3−xNixTi4O12(where x = 0.05, 0.1, and 0.2) ceramics for the dielectric and electrical properties

Journal of Materials Science: Materials in Electronics - We have investigated a low-temperature chemical route of the synthesis and measured the dielectric, electrical and morphological...     

Influence of Zn doping on microstructure,dielectric, and electric properties in Bi2/3Cu3Ti4O12 ceramic synthesized by the semi-wet method

Journal of Materials Science: Materials in Electronics - Zn-doped and undoped BCTO ceramics (Bi2/3Cu3?xZnxTi4O12, where x?=?0, 0.05, 0.1, and 0.2) were prepared by semi-wet...     

Electrochemical impedance studies of capacity fading of electrodeposited ZnO conversion anodes in Li-ion battery

Electrodeposited ZnO coatings suffer severe capacity fading when used as conversion anodes in sealed Li cells. Capacity fading is attributed to (i) the large charge transfer resistance, \(R_{\mathrm{ct}}\) (300–700 \(\Omega \)) and (ii) the low \(\hbox {Li}^{+}\) ion diffusion coefficient, \(D_{\mathrm{Li}}^{+}\ (10^{-15}\) to \(10^{-13}\hbox { cm}^{2}\hbox { s}^{-1})\). The measured value of \(R_{\mathrm{ct}}\) is nearly 10 times higher and \(D_{\mathrm{Li}}^{+}\) 10–100 times lower than the corresponding values for \(\hbox {Cu}_{2}\hbox {O}\), which delivers a stable reversible capacity.     

印度Ispat CSP工厂生产优质热轧卷

1998年,印度Ispat公司开始投产CSP生产线(图1).这个生产线原计划年产300万t热轧卷,年产210万t高炉提供铁水.Midren装置年产160万吨海绵铁.     

Bioethanol production from renewable polymer lichenan using lichenase from an alkalothermophilic Thermomonospora sp. and thermotolerant yeast

Biomass feedstocks available decentrally will be more commodious for localized biorefinery approach than the exhaustive large scale and centralized plants driven by cost intensive technology. Lichen is present in a wide range of habitats in a distributed manner. A maximum hydrolysis of 73%-76% for lichenan from Cetraria islandica, Usnea barbata and Parmelia sp. were obtained in 24 h using lichenase from an alkalothermophilic Thermomonospora sp. wherein the hydrolysis was 100% with commercial enzyme Accellerase™1000. The synergistic role of β-glucosidase in lichenan hydrolysis was demonstrated by the exogenous addition of β-glucosidase to Thermomonospora lichenase which resulted in complete hydrolysis. The hydrolysates of lichenan obtained using Accellerase or a cocktail of Thermomonospora lichenase and β-glucosidase when fermented with free cells of Saccharomyces at 40 °C produced an ethanol yield of 0.45 g/g-0.48 g/g with theoretical conversion efficiencies of 93%-96%. The Ca-alginate immobilized yeast cells were reused eight times at 40 °C with 100% fermentation efficiency.     

Modelling and numerical simulation of liquid–solid circulating fluidized bed system for protein purification

A novel liquid–solid circulating fluidized bed (LSCFB) was modelled for protein recovery from the feed broth. A typical LSCFB system consists of downer and riser, integrating two different operations simultaneously. A general purpose, extensible, and dynamic model was written based on the tanks-in-series framework. The model allowed adjusting the degree of backmixing in each phase for both columns. The model was validated with previously published data on extraction of bovine serum albumin (BSA) as model protein. Detailed dynamic analysis was performed on the protein recovery operation. The interaction between the riser and downer were captured. Parametric studies on protein recovery in LSCFB system were carried out using the validated model to better understand the system behaviour. Simulation results have shown that both production rate and overall recovery increased with solids circulation rate, superficial liquid velocity in the downer and riser, and feed solution concentration. The model was flexible and could use various forms of ion exchange kinetics and could simulate different hydrodynamic behaviours. It was useful to gain insight into protein recovery processes. The general nature of the model made it useful to study other protein recovery operations for plant and animal proteins. It could also be useful for further multi-objective optimization studies to optimize the LSCFB system.     

Effect of oleylamine on microwave synthesized Cu2ZnSnS4 nanocrystals for photovoltaic junctions

Cu₂ZnSnS₄ (CZTS) with its high absorption coefficient, optimal band gap, and non‐toxic, earth‐abundant elemental constituents is a promising absorber material for low cost and high‐performance photovoltaics. CZTS nanocrystals were prepared by microwave‐assisted thermolysis method using ethylene glycol solvent in a rapid and energy efficient process with and without oleylamine as additional capping agent. X‐ray diffraction data indicated crystallite sizes of 5 and 12 nm respectively. Raman spectra showed the formation of pure Cu₂ZnSnS₄ phase in both cases. With pure ethylene glycol solvent, field emission scanning electron microscopy images showed particle sizes around 250 nm, ultraviolet‐visible absorption data gave optical band gap of 1.52 eV and Hall measurements yielded electrical resistivity ~70 Ωcm, carrier density ~2.7 × 10¹⁶/cm³, and hole mobility ~3.24 cm²/Vs. Adding optimum amount of oleylamine reduced the particle size to 100 nm and lower. The optical band gap reduced to 1.48 eV and electrical resistivity, carrier concentration, and Hall mobility changed to ~5.9 × 10⁴ Ωcm, 2.57 × 10¹²/cm³, and 4.1 cm²/Vs respectively. A knee voltage of ~0.8 V shown by CZTS/CdS p‐n junction indicated that a good V_oc can be expected from a solar cell constructed with the CZTS nanocrystals as absorber layer.