The biodegradation of N-methyl-2-pyrrolidone in water by sewage bacteria

The biodegradability of N-methyl-2-pyrrolidone was studied using a static die-away system and a semi-continuous activated sludge system. The biodegradation was followed by gas-liquid chromatographic analysis as well as by monitoring the change in chemical oxygen demand of the culture mixture. Results show that N-methyl-2-pyrrolidone is readily degradable under these conditions. However, the metabolite has an appreciable oxygen demand and is shown by infra-red spectroscopy to be a carbonyl compound.     

Modeling of Convective Drying of Sawdust Using a Reaction Engineering Approach

Drying as a simultaneous heat and mass transfer process can be modeled via the reaction engineering approach (REA) where the apparent activation energy of the material is established and related to its moisture content during drying. This relationship is unique as the normalized activation energies can be collapsed into a single equation irrespective of the drying conditions and dryer types. Here, REA was applied to model the drying kinetics of sawdust using convective hot air in a laboratory setup. The normalized (relative) activation energy curve generated from one drying experiment was employed to predict the drying kinetics and temperature profiles. The REA can describe well the convective drying kinetics of sawdust, and major physics of the drying process was captured well with this technique.     

Hausmannite Mn3O4 as a positive active electrode material for rechargeable aqueous Mn‐oxide/Zn batteries

Batteries with manganese (di)oxide/zinc chemistry and aqueous‐based electrolytes have the potential to address energy storage demands of stationary applications primarily because of the abundant availability of Zn and Mn‐oxides, their intrinsic low cost, and the high specific/volumetric charge capacities. Herein, we report the use of Mn₃O₄ (hausmannite phase of manganese oxide) as the positive electrode material in a rechargeable near‐neutral Mn‐oxide/Zn battery configuration. Electrochemical investigations reveal that the hausmannite phase can activate for charge/discharge processes during the first 40 to 50 cycles and then a maximum capacity is obtained. This material shows excellent reversibility (~800 cycles) in keeping more than 65% of its maximum capacity. For the first time, the hausmannite activation mechanism was better understood under near‐neutral conditions. By using different characterization techniques (X‐ray powder diffraction [XRD], inductively coupled plasma‐optical emission spectrometry [ICP‐OES], X‐ray photoelectron spectroscopy [XPS], and energy dispersive X‐ray spectroscopy [EDS]) formation of Zn‐based compounds at the electrode surface was confirmed. One of the compounds formed is the layered double hydroxide (Zn₄SO₄[OH]₆ · 5H₂O) that forms as a side product. No direct evidence for intercalation of zinc ions was observed. Electrochemical experiments in different aqueous/organic electrolytes has shown that proton intercalation plays a significant role in the charge‐storage mechanism, while the activation process itself proceeds, most likely, through the formation of Zn‐species at the electrode surface.     

Process simulation and debottlenecking for an industrial cocoa manufacturing process

Cocoa is a common ingredient for various food and confectionery products. Industrial production of this ingredient however is normally not optimised, due to the lack of appropriate analytical tools. Furthermore, cocoa processing is normally operated in semi-continuous mode, and this adds to the difficulty in optimising the various unit operations involved. In this work, a computer-aided process simulation tool was used to model and debottleckneck an industrial cocoa manufacturing process, with the aim to identify an economically viable production scheme that would double the current production rate.     

A Comparative Approach for the Preparation and Physicochemical Characterization of Lecithin Liposomes Using Chloroform and Non‐Halogenated Solvents

Organic solvents used in various pharmaceutical preparations may be associated with chronic health effects, with special emphasis on halogenated solvents. Liposomes, lipid bilayer membrane carriers, have potential applications in targeted drug delivery systems. The non‐halogenated solvents, acetonitrile and ethanol, were used in comparison to commonly used chloroform. The effect of solvents and dispersion medium was demonstrated using physicochemical properties, stability studies and hemolytic activity. Increased sonication time showed decreased particle size in phosphate buffer saline and water medium. Vesicles prepared from all solvents exhibited better stability in phosphate saline buffer than water when evaluated by particle size and zeta potentials. Liposomes showed a positive zeta potential in buffer solution whereas liposomes in water showed negative zeta potential. In vitro hemolytic activity of liposomes was done with fresh human red blood cells. Results in buffer solution were in the range of 1–4 % which further proved this medium superior to pure water. The findings of this study are helpful in suggesting the formulation of thin films by less hazardous solvents in terms of the environmental integrity and human health.     

Physical properties of normal grade biodiesel and winter grade biodiesel

In this study, optical and thermal properties of normal grade and winter grade palm oil biodiesel were investigated. Surface Plasmon Resonance and Photopyroelectric technique were used to evaluate the samples. The dispersion curve and thermal diffusivity were obtained. Consequently, the variation of refractive index, as a function of wavelength in normal grade biodiesel is faster than winter grade palm oil biodiesel, and the thermal diffusivity of winter grade biodiesel is higher than the thermal diffusivity of normal grade biodiesel. This is attributed to the higher palmitic acid C(16:0) content in normal grade than in winter grade palm oil biodiesel.     

Transient two-dimensional heat conduction analysis of electronic packages by coupled boundary and finite element methods

Electronic packages experience large temperature excursions during their fabrication and under operational conditions. Inherent to electronic packages are the presence of geometric and material discontinuities. The regions where adhesive bond lines intersect with convective heat-loss surfaces are the most critical locations for failure initiation due to heat flux singularities and extreme thermo-mechanical stresses. Thus, accurate calculation of the flux field, as well as the temperature field, is essential in transient thermo-mechanical stress analysis. Although the finite element method (FEM) is highly efficient and commonly used, its application with conventional elements suffers from poor accuracy in the prediction of the flux field in these regions. The accuracy of the results from the boundary element method (BEM) formulation, which requires computationally intensive time-integration schemes, is much higher than that of the FEM. However, in this study, a novel boundary element-finite element coupling algorithm is developed to investigate transient thermal responses of electronic packages consisting of dissimilar materials.