This review article summarizes research directed toward microwave heating in the oil chemistry. Topics to be discussed include microwave synthesis of surfactants, extraction methods, modification of crude oil properties, and degradation of surfactants. The specific effects of microwave heating, which cannot be obtained by conventional heating in particular, are explained.
There is increased interest in winter canola as an oilseeds crop for production of oil or biodiesel in the southeastern United States, but research has been limited. The objective of this study was to evaluate the effect of N (0, 60, 120, 180 kg N ha–1) on productivity, oil content and oil composition of winter canola grown for two cropping seasons at three locations in Mississippi (Stoneville, and two locations at Verona: Verona upland silt loam, Verona-SL and Verona upland clay, Verona-C). Overall, increasing N application rates resulted in corresponding stepwise increase in seed yields in the two locations at Verona, whereas yields in the 60 and 120 kg N ha–1 at Stoneville were not different from each other. Seed yields reached 3,383 and 3,166 kg ha–1 in the 180 kg N treatment at Verona and at Stoneville, respectively. Oil yields were also increased with increasing N rates, however, oil yields at 60 and 120 kg N ha–1 at Verona-C were not different from each other. Oil yields in the 180 kg N ha–1 treatment reached 1,363 and 1,151 kg ha–1 at Verona-SL and Stoneville, respectively. At Verona-SL location, higher N rates resulted in increased stearic acid compared to the lower N rates. However, the reverse effect was observed on the concentration of linolenic acid, which was lower at higher N rates. Also at that location, N application reduced the concentration of linoleic acid. At the Verona-C location, N application at 180 kg N ha–1 reduced concentration of linolenic acid relative to the other fertility treatments. Overall, the increase in N application rates resulted in greater yield (kg FA ha–1) of palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, eicosanoic, behenic, lignoceric and nervonic acids in all three locations, with N at 0 kg ha–1 providing the lowest yields and N at 180 kg ha–1 providing the highest yields. Winter canola production in the hot humid environment of southeastern United States can be successful and could provide seed and oil yields comparable to yields from major winter canola production areas.
A study was conducted to differentiate lard, chicken fat, beef fat and mutton fat using Gas Chromatography Mass Spectrometry (GC-MS) and Elemental Analyzer–Isotope Ratio Mass Spectrometry (EA-IRMS). The comparison of overall fatty acid data showed that lard and chicken fat share common characteristics by having palmitic, oleic and linoleic acid as major fatty acids while beef and mutton fats shared common characteristics by possessing palmitic, stearic and oleic acid as major fatty acids. The direct comparisons among the fatty acid data, therefore, may not be suitable for discrimination of different animal fats. When the fatty acid distributional data was subjected to Principle Component Analysis (PCA), it was demonstrated that stearic, oleic and linoleic acids as the most discriminating parameters in the clustering of animal fats into four subclasses. The bulk carbon analysis of animal fats using EA-IRMS showed that determination of the carbon isotope ratios (δ13C) would be a good indicator for discriminating lard, chicken fat, beef fat and mutton fat. This would lead to a faster and more efficient method to ascertain the source of origin of fats used in food products.
In the present study, we show that four unusual cholesterol precursors, 5α-cholesta-8,14-dien-3β-ol, 4-methyl-5α-cholesta-8,24-dien-3β-ol (4-methylzymosterol), 4,4,14-trimethyl-5α-cholesta-8,24-dien-3β-ol (lanosterol), and 4,4-dimethyl-5α-cholesta-8,24-dien-3β-ol (4,4-dimethylzymosterol) are present in testes of the limpet Cellana grata, which is part of one of the most primitive gastropod families (Nacelllidae Family). The distribution of these sterols in testes and ovaries of four dominant species of limpets, Cellana grata, Cellana toreuma, Nipponacmea concinna, and Nipponacmea fuscoviridis, was examined by capillary gas chromatography-mass spectrometry. Based on the data, we discuss about the biological roles and possible application as bio-resources of these sterols. This is the first identification of 5α-cholesta-8, 14-dien-3β-ol, 4-methylzymosterol, and 4,4-dimethylzymosterol in marine invertebrate gonads.
The miscibility of Langmuir monolayers of egg yolk lecithin (eggPC) with n-hexadecanoic acid (PA), 1-hexadecanol (HD), and their equimolar mixture (PA/HD) was investigated thermodynamically and morphologically. Surface pressure (π)-molecular area (A) and surface potential (ΔV)-A isotherms for the binary and ternary systems were measured, employing the Wilhelmy method and the ionizing 241Am electrode method, respectively. From the thermodynamic perspective, eggPC was partially miscible with PA, HD, and PA/HD within the monolayer state, in terms of an excess Gibbs free energy of mixing calculated from the π-A isotherms and a two-dimensional phase diagram based on a monolayer collapse pressure. This was also directly supported by phase behavior observations using fluorescence microscopy (FM). EggPC formed a typical liquid-expanded (LE) monolayer, and the others formed liquid-condensed (LC) monolayers. The FM images exhibited miscible modes at middle molar fractions of PA, HD, and PA/HD, and immiscible patterns at large molar fractions for all the systems examined. A new finding in the present study was that the eggPC/PA, eggPC/HD, and eggPC/(PA/HD) systems exhibited partial miscibility, although the systems were made of both LE (eggPC) and LC monolayers (the others). This miscibility is considered to be attributable to the molecular species comprising eggPC.
To develop an efficient and fluorine-free solubilizer for a water/supercritical CO2 microemulsion (W/CO2 μE), in this study, a highly methyl-branched alkyl, isostearyl group was focused on as a CO2-philic tail, and the custom-made isostearyl surfactant, sodium 2-(4,4-dimethylpentan-2-yl)-5,7,7-trimethyloctyl sulfate (SIS1) was synthesized. The surface tension (γ) of an aqueous SIS1 solution was measured at ambient pressure as a function of surfactant concentration, and it was found to be 25 mN/m at concentrations of > 1.5 mM. A low γ value can generally be reached only by a fluorocarbon surfactant, which implies that SIS1 has an excellent solubilizing power for the W/CO2 μE, similar to some fluorocarbon surfactants reported previously. Visual observations of the SIS1/W/CO2 mixtures revealed the formation of transparent single phases without separated water, identified as W/CO2 μE. The μE was well-stabilized at pressures > 210 bar and temperatures > 55 °C. At 75 °C and 370 bar, SIS1 was found by spectral measurements using a water-soluble UV-light absorber to solubilize water contents up to a maximum water-to-surfactant molar ratio (W0) = 50. The achievement of W0 = 50 in a W/CO2 μE system has not been reported previously in similar hydrocarbon surfactant/W/CO2 systems, and this demonstrates that a highly methyl-branched alkyl group can act as a good CO2-philic group for a W/CO2 -type surfactant.
Cationic gemini surfactants having a quaternary ammonium headgroup have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an amide bond, while the quaternary ammonium headgroup is introduced onto the cis double bond of oleic acid. The Krafft temperature of these surfactants drops below room temperature (ca. 25°C) when the counterion is exchanged from Br– to Cl–. The aqueous solution properties of the Cl series of surfactants have been assessed by means of pyrene fluorescence, dynamic light scattering (DLS), and static surface tension measurements. An increased hydrocarbon chain length results in a lower critical micelle concentration (cmc) and a higher adsorption efficiency at the air/aqueous solution interface. Surface tension measurements suggest the formation of premicelles at concentrations below cmc, whereas, above cmc, DLS indicates the formation of micellar aggregates whose diameter ranges from 5 to 10 nm. We, furthermore, characterized the adsorption of these surfactants to the silica/aqueous solution interface and observed their spontaneous adsorption to the solid surface by electrostatic and intermolecular hydrophobic interactions. The combination of soft-contact imaging atomic force microscopy (AFM) and force-curve data suggests bilayer formation above cmc, which is reflective of the large packing parameter of the gemini surfactants. Interestingly, we found the repulsive interaction observed during compression of the adsorbed layer to be relatively weak, as a result of the low adsorption density and/or the loose molecular packing arrangement, which arises from the asymmetric structure.
The lyotropic phase behavior of the cyclic form surfactin (CS) produced by Bacillus subtilis and its linear derivative in aqueous solution was evaluated for the first time by using polarized light microscopy and small-angle X-ray scattering (SAXS). By polarized light microscopy, the aqueous solutions of CS at the concentrations above 50 wt% were optically anisotropic and gave mosaic textures, suggesting the formation of lamella structures, while those of the linear surfactin (LS) were optically isotropic and no distinctive textures were observed. SAXS diffractograms of the CS solution above 50 wt% clearly gave the three peaks whose spacing ratio of 1: 2: 3, indicating the presence of the lamellar (Lα) phase, while those of the LS solution gave multiple peaks whose spacing ratios of √2: √3: √4: √6: √8, confirming the bicontinuous cubic (V2) phase of the symmetry Pn3m. It was also found that the lamellar phase with CS was composed of not ordinary bilayer but interdigitated bilayer with the unusual packing of the acyl chain region. These results clearly demonstrated that the cyclic peptide structure plays a key role in regulating their self-assembly, and naturally occurring CS is likely to form lamellar structure by balancing bulky peptide headgroups with interdigitated packing of their acyl chains.
We have recently proposed a new general concept regarding amphiphilic materials that have been named as “active interfacial modifier (AIM).” In emulsion systems, an AIM is essentially insoluble in both water and organic solvents; however, it possesses moieties that are attracted to each of these immiscible liquid phases. Hence, an AIM practically stays just at the interface between the two phases and makes the resulting emulsion stable. In this study, the effects of silicone oil species on the dispersion stability of water-in-oil (W/O) emulsions in the presence of an AIM sample were evaluated in order to understand the destabilization mechanism in such emulsion systems. The AIM sample used in this study is an amphiphilic polymer consisting of a silicone backbone modified with hydrocarbon chains and hydrolyzed silk peptides. The Stokes equation predicts that the sedimentation velocity of water droplets dispersed in a continuous silicone oil phase simply depends on the expression (ρ – ρ0)/η assuming that the droplet size is constant (where ρ is the density of the dispersed water phase, ρ0 is the density of the continuous silicone oil phase, and η is the viscosity of the oil phase). The experimental results shown in this paper are consistent with the Stokes prediction: i.e., in the low-viscous genuine or quasi-Newtonian fluid region, the dispersion stability increases in the following order: dodecamethylpentasiloxane (DPS) < decamethylcyclopentasiloxane (D5) ≤ dodecamethylcyclohexasiloxane (D6). This order agrees well with the order obtained by using the expression (ρ – ρ0)/η as DPS > D5 > D6. This indicates that our emulsion system experiences destabilization through sedimentation, but hardly any coalescence occurs owing to the presence of an additional third phase consisting of the AIM that stabilizes the silicone oil/water interface in the emulsions.
Recent findings have implicated the involvement of interferon-γ (IFN-γ), a part of the Th1 cytokine response, in the retinal inflammation of diabetic patients. In the present study, we investigate whether hyperglycemia relates to the expression of interleukin 18 (IL-18), and leads to the production of IFN-γ in the retinas of Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus. Plasma blood glucose, triglyceride and cholesterol levels in 60-week-old OLETF rats, in which the development of diabetes mellitus was observed, were significantly higher than in 60-week-old Long-Evans Tokushima Otsuka (LETO) rats used as normal controls. The expression levels of genes that cause IL-18 activation (IL-18, IL-18 receptor and caspase-1) in OLETF rats were increased at 60 weeks of age, and the levels of IL-18 and IFN-γ in 60-week-old OLETF rat retinas were also higher than in 60-week-old LETO rats. Furthermore, IFN-γ levels increased with increasing IL-18 levels in the retinas of OLETF rats, and a close relationship was observed between the levels of IL-18 and HbA1c. The rapid increase in plasma glucose levels following the oral administration of glucose solution (3.0 g/kg) did not affect the IL-18 and IFN-γ levels in the retinas of LETO rats, whereas the levels in the retinas of OLETF rats increased significantly. In conclusion, the expression of IL-18 is increased in the retinas of OLETF rats, and chronic hyperglycemia may accelerate the release of IL-18 and IFN-γ from inflammatory cells in retinal blood vessel. It is possible that IFN-γ production via IL-18 in the retinas of 60-week-old OLETF rats is caused by hyperglycemia, and plays a role in the inflammation of the OLETF rat retinas.
The objective of this research was the modification of our biodiesel fuel (BDF) production process to make higher quality BDF. The existing process which does not include a water washing process for raw BDF, has the advantage of no wash water discharge, but occasionally the resultant BDF is of lower grade due to residual ingredients. First, we attempted to integrate water washing into the existing process. After being neutralized and washed with H2SO4, the raw BDF was then washed with water equal to 20% of the raw BDF volume. A good separation of BDF and wash water was achieved, and the resultant wash water contained less than 2% methanol. Second, we evaluated biodegradation of the resultant wash water constituents, and 70% of the strains isolated from environmental samples removed 80 to 90% of total organic carbon. Among these, strain No. 20-68 removed both glycerol and methanol in the wash water within 7 days and was identified as Fusarium falciforme, a ubiquitous environmental microorganisms. These results suggest that if the wash water is released to the environments, the effects on environmental microorganisms will be minimal.
A numerical simulation model for laminar flow of nanofluids in a pipe with constant heat flux on the wall was built to study the effect of the Reynolds number on convective heat transfer and pressure loss. The investigation was performed for hybrid nanofluids consisting of CuO-Cu nanoparticles and compared with CuO and Cu in which the nanoparticles have a spherical shape with size 50, 50, 50nm respectively. The nanofluids were prepared, following which the thermal conductivity and dynamic viscosity were measured for a range of temperatures (10 -60°C). The numerical results obtained were compared with the existing well-established correlation. The prediction of the Nusselt number for nanofluids agrees well with the Shah correlation. The comparison of heat transfer coefficients for CuO, Cu and CuO-Cu presented an increase in thermal conductivity of the nanofluid as the convective heat transfer coefficient increased. It was found that the pressure loss increases with an increase in the Reynolds number, nanoparticle density and particle volume fraction. However, the flow demonstrates enhancement in heat transfer which becomes greater with an increase in the Reynolds number for the nanofluid flow.