Evaluation of emu oil extraction methods and their effects on physical and rheological behavior

In this study we evaluated the efficiency of six extraction methods for emu fat based on the quantification of yield, color, density, refraction index, and rheological behavior. Both physical methods (Bain Marie, rotary evaporator, fusion, ultrasound, and microwave) and chemical methods (solvents) were evaluated. Oil properties were compared with commercial emu oil as a reference. Solvent‐based extraction produced the greatest yield (72.8%). Among the physical methods, the greatest yield was produced by the ultrasound method (42.8%). In general, properties were similar to those reported for vegetable oils. The rotary evaporator method showed the greatest difference in total color (ΔE) in comparison with a commercially‐produced reference, while the fusion method showed the smallest ΔE. No statistically significant differences were found between the density and refraction index of the treated samples and those of the reference. Kinematic viscosity increased significantly in samples extracted via microwave method. All samples displayed pseudoplastic behavior. The data showed a good fit to the power law model (R² > 0.90). The consistency coefficient and flow behavior index were determined for all methods. Practical applications: Therapeutic applications for oil have been posited for emu oil. In pharmaceutical products, oils are used as emollients and as carriers for medicinal substances. The practical importance of an oil depends on its physical properties, thus a thorough understanding of those physical properties is very important for identifying potential applications. These properties are affected by the extraction method employed; the present paper evaluates the effects of a range of extraction methods on yield efficiency, as well as physical and rheological properties. Novel extraction methods such as ultrasound and microwave are also evaluated in this study.     

Simultaneous degradation of atrazine and simazine by a binary culture of Stenotrophomonas maltophilia and Arthrobacter sp. in a two‐stage biofilm reactor

BACKGROUND: The impact of mixtures of chloro‐triazinic herbicides, such as atrazine and simazine, on aquatic ecosystems is of environmental concern. To study their biodegradation under various operational conditions, a binary community comprising Stenotrophomonas maltophilia and Arthrobacter sp. attached to the porous support of a packed bed reactor, was evaluated. RESULTS: The genetic analysis of the two atrazine‐degrading strains revealed that genes atzA, atzB, atzC are present in both bacteria, but only S. maltophilia possess atzD. Thus, by cultivating Arthrobacter sp. on these herbicides, cyanuric acid accumulation was observed. When the binary community was cultivated in the biofilm reactor, at all the loading rates probed, both herbicides were entirely removed. However, complete biodegradation of cyanuric acid was not achieved. CONCLUSIONS: Even with a two‐stage reactor, cyanuric acid was only partially removed. This fact could be attributed to the absence, in the second stage, of an easily degradable energy source, required by S. maltophilia for the uptake and cometabolic degradation of the recalcitrant heterocyclic ring. Responding to differences in nutritional conditions prevailing at each reactor stage, local differences in species' predominance were clearly detected by microbiological and molecular biology methods. Copyright © 2010 Society of Chemical Industry     

Fuel grade ethanol by diffusion distillation: an experimental study

BACKGROUND: Fuel grade ethanol (anhydrous ethanol) is considered to be an excellent alternative clean burning fuel to gasoline. It is now used as an additive to gasoline to enhance its octane number and combustibility. Owing to its high energy values, ethanol is the most promising future biofuel. Because of azeotrope formation, anhydrous ethanol cannot be achieved by conventional distillation. Diffusion distillation is one of the several processes that can be used to separate azeotropes. Diffusion distillation takes advantage of differences in relative rates of diffusion using inert gas as selective filter. RESULTS: Effect of vaporization temperature and feed composition on diffusion distillation of an ethanol–water mixture using air as the inert gas has been studied. A new quantity S_az(N₂/N₁) has been suggested to find the optimum vaporization temperature. In the present study this was found to be about 46 °C. The pseudo‐azeotrope has been observed at 0.697 mole fraction of ethanol at a vaporization temperature of 50 °C. Separation is effected by diffusion distillation even at the azeotropic ethanol mole fraction of 0.894. The experimental results were compared with a Stefan–Maxwell equations based mathematical model and found to be in good agreement with theoretical results. CONCLUSIONS: Experimental results demonstrate that fuel grade ethanol can be produced by diffusion distillation. The new quantity S_az(N₂/N₁) is a key variable for vaporization temperature optimization. Copyright © 2011 Society of Chemical Industry     

Effect of particle size on thermomechanical properties of particulate polymer composite

Particulate composite materials (PCM) consisting of a matrix reinforced by micro to nano-sized dispersed phase are receiving the attention of designers as a promising futuristic materials. This study unearths the thermal and mechanical behavior of maleic anhydride grafted polypropylene/silica (MA-g-PP/silica) composites for reinforcement ranging from micro- to nano-size. The monodisperse silica spherical particles were used in all the formulations of composites. Further the volume fraction was kept the same in all the compounded thermoplastic composites ranging from 100 nm to 130 μm in a co-rotating conical twin-screw micro-compounder. The micrographs were obtained from transmission electron microscopy (TEM) and the scanning electron microscopy (SEM). The SEM and TEM results revealed a good dispersion of the silica spheres within the MA-g-PP matrix. The compounded composite materials were injection molded to fabricate tensile test specimens (ASTM D638 type V) and tested for tensile properties. In order to investigate the effect of particle size on crystallite structure of the matrix, the composites were tested on differential scanning calorimeter and X-ray diffraction (WAXD). The thermal stability and degradation kinetics were studied via thermogravimetric analysis. The results show increase in crystallization rate, crystallinity percentage, Young’s modulus, strength and thermal stability of MA-g-PP by addition of the silica particles. Further it was observed that the small-sized dispersed phase had better overall thermal and mechanical behavior than its larger sized counterpart.     

The effect of microencapsulated phase change materials on the rheology of geopolymer and Portland cement mortars

The effect of microencapsulated phase-change materials (MPCM) on the rheological properties of pre-set geopolymer and Portland cement mortars was examined. Microcapsules with hydrophilic and hydrophobic shells were compared. The shear rate dependency of the viscosities fitted well to a double Carreau model. The zero shear viscosities are higher for geopolymer mortar, illustrating poorer workability. The time evolution of the viscosities was explored at shear rates of 1 and 10 s⁻¹. New empirical equations were developed to quantify the time-dependent viscosity changes. The highest shear rate disrupted the buildup of the mortar structures much more than the lower shear rate. Microcapsules with a hydrophobic shell affect the rheological properties much less than the microcapsules with a hydrophilic shell, due to the higher water adsorption onto the hydrophilic microcapsules. Shear forces was found to break down the initial structures within geopolymer mortars more easily than for Portland cement mortars, while the geopolymer reaction products are able to withstand shear forces better than Portland cement hydration products. Initially, the viscosity of geopolymer mortars increases relatively slowly during due to formation of geopolymer precursors; at longer times, there is a steeper viscosity rise caused by the development of a 3D-geopolymer network. Disruption of agglomerates causes the viscosities of portland cement mortars to decrease during the first few minutes, after which the hydration process (increasing viscosities) competes with shear-induced disruption of the structures (decreasing viscosities), resulting in a complex viscosity behavior.     

Design,Synthesis and Evaluation of 2,4-Diaminoquinazoline Derivatives as Potential Tubulin Polymerization Inhibitors

Microtubules are highly dynamic polymers composed of α- and β-tubulin proteins that have been shown to be potential therapeutic targets for the development of anticancer drugs. Currently, a wide variety of chemically diverse agents that bind to β-tubulin have been reported. Nocodazole (NZ) and colchicine (COL) are well-known tubulin-depolymerizing agents that have close binding sites in the β-tubulin. In this study, we designed and synthesized a set of nine 2,4-diaminoquinazoline derivatives that could occupy both NZ and COL binding sites. The synthesized compounds were evaluated for their antiproliferative activities against five cancer cell lines (PC-3, HCT-15, MCF-7, MDA-MB-231, and SK-LU-1), a noncancerous one (COS-7), and peripheral blood mononuclear cells (PBMC). The effect of compounds 4 e and 4 i on tubulin organization and polymerization was analyzed on the SK-LU-1 cell line by indirect immunofluorescence, western blotting, and tubulin polymerization assays. Our results demonstrated that both compounds exert their antiproliferative activity by inhibiting tubulin polymerization. Finally, a possible binding pose of 4 i in the NZ/COL binding site was determined by using molecular docking and molecular dynamics (MD) approaches. To our knowledge, this is the first report of non-N-substituted 2,4-diaminoquinazoline derivatives with the ability to inhibit tubulin polymerization.     

Anisotropic thermal conductivity of silicon nitride ceramics containing carbon nanostructures

Silicon nitride (Si₃N₄) composites containing carbon nanotubes (CNTs) or graphene nanoplateles (GNPs) are of great relevance in the electronic and aerospace industries where the search for new materials with enhanced and anisotropic thermal conductivity to work in harsh environments is a strategic guideline. Here we study thermal conduction in Si₃N₄ composites with different amounts of carbon nanostructures. The effects of the nanostructure orientation respect the heat flux, the testing temperature and the α/β Si₃N₄ phase ratio are analyzed. The addition of CNTs and GNPs leads to an anisotropic thermal response, decreasing the through-thickness thermal conductivity of the Si₃N₄ composites and raising the in-plane thermal conductivity, especially for GNPs that enhance it up to twice that of the monolithic Si₃N₄. This effect is related to the preferred orientation of the nanostructures that gives a less resistive network in the in-plane direction and the intrinsic anisotropy of their thermal conductivity.     

The effect of scaleup on the processing behavior of a blend exhibiting phase inversion during compounding

The scaleup behavior of blends exhibiting phase inversion during compounding in batch mixers was studied. Similar morphological changes were observed during compounding of polystyrene/polyethylene blends of different batch sizes ranging from 12g to 240g. The time to achieve a continuous phase of the major component, polystyrene, was shown to depend on the scale of the mixing device. Based on visual observation of the morphological changes, a constant nominal‐maximum‐shear‐rate scaleup condition was used. Upon a five‐fold increase in batch size the time to phase inversion increased by a factor of 3. This change is explained using a combination of the reduced specific area and reduced mechanical energy input under the experimental conditions. A novel blade design using modular triangular elements was constructed and results from radial and axial scaleup using the new blades are presented. Similarities between the triangular and roller blades are used to highlight the importance of the high‐shear region in determining the softening rate of the polystyrene pellets. The flexibility of the blade design was exploited to study the effect of blade configuration on the time to phase inversion. A relative stagger parameter is introduced to explain the observed dependence. Increasing the relative stagger decreased the stress transfer to the batch and increased the time to phase inversion. Implications of these results for mixing in the kneading sections of twin‐screw extruders is discussed.     

An improved algorithm for the three‐fluid‐phase VLLE flash calculation

The VLLE flash is important in water and hydrocarbons mixtures, hydrocarbon and CO₂ rich mixtures, and hydrocarbon methane rich mixtures that are encountered in reservoir performance and recovery studies. A robust VLLE flash algorithm is proposed. The equilibrium and mass balance equations are solved as a constrained minimization problem. An inverse barrier function is used to handle the inequality constrains to solve for the phase fractions. It warrants always arriving to the solution. The challenging cases analyzed showed that the initialization procedure proposed, together with successive substitution iteration in the outer loop, is a good method for a stable VLLE flash algorithm, even near critical points. Whenever the result is in the region outside the three‐phase physical domain, the solution suggests that the system has fewer phases. In one of the cases analyzed, a region with three liquid phases was encountered and the algorithm found two different solutions with positive phase fractions. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3081–3093, 2015     

Controllability Analysis of Process Alternatives for Biobutanol Purification

Biobutanol has characteristics similar to petroleum fuel and is considered as a superior biofuel compared to ethanol. The development of technologies for biobutanol production by fermentation has resulted in higher final biobutanol concentrations together with less energy‐intensive separation and purification techniques. These new technological developments have the potential to provide a production process for biobutanol that is economically viable in comparison to the petrochemical pathway for its production. The control properties of four different possible process designs for biobutanol purification are analyzed. The results, using the singular value decomposition technique, indicated that the scheme where only biobutanol flow is purified, and both ethanol and acetone leaving the purification process mixed with water and biobutanol traces, showed the best control properties.