Regulation of Phosphatidic Acid Levels in <Emphasis Type="Italic">Trypanosoma cruzi</Emphasis>

Lipid kinases and phosphatases play essential roles in signal transduction processes involved in cytoskeletal rearrangement, membrane trafficking, and cellular differentiation. Phosphatidic acid (PtdOH) is an important mediator lipid in eukaryotic cells, but little is known regarding its regulation in the parasite Trypanosoma cruzi, an agent of Chagas disease. In order to clarify the relationship between PtdOH metabolism and developmental stages of T. cruzi, epimastigotes in culture were subjected to hyperosmotic stress (~1,000 mOsm/L), mimicking the environment in the rectum of vector triatomine bugs. These experimental conditions resulted in differentiation to an intermediate form between epimastigotes and trypomastigotes. Morphological changes of epimastigotes were correlated with an increase in PtdOH mass accomplished by increased enzyme activity of diacylglycerol kinase (DAGK, E.C. 2.7.1.107) and concomitant decreased activity of phosphatidate phosphatases type 1 and type 2 (PAP1, PAP2, E.C. 3.1.3.4). Our results indicate progressive increases of PtdOH levels during the differentiation process, and suggest that the regulation of PtdOH metabolism is an important mechanism in the transition from T. cruzi epimastigote to intermediate form.     

Effect of Water on the Ethanolysis of Waste Cooking Soybean Oil Using a Tin(II) Chloride Catalyst

Biodiesel production from cheap lipid raw materials is economically welcome, but a high free fatty acids (FFA) content makes it incompatible with traditional alkaline catalysts. Although liquid mineral acids are alternatively used, serious drawbacks such as high corrosiveness and large effluent generation, as well as the impossibility of catalyst reuse compromises its application. Contrarily, solid acid catalysts appear to be an attractive option; however, the water present or generated during FFA esterification provokes the leaching and deactivation of these catalysts. Thus, in this work we have evaluated the use of tin chloride SnCl₂, which is less corrosive, water tolerant, and a recyclable Lewis acid catalyst, on FFA ethanolysis using waste cooking oil samples (WCO). Additionally, the main kinetic parameters of the reactions were assessed. Compared to pTSA (p-toluenesulfonic-acid), a catalyst also evaluated, SnCl₂ efficiently promoted FFA ethanolysis even in the presence of high amounts of water (ca. 0.1–5.0% w/w). Moreover, the homogeneous SnCl₂ catalyst was easily recovered and reused successively, without loss of activity.     

Equilibrium,kinetic and thermodynamic study of removal of reactive orange 12 on platinum nanoparticle loaded on activated carbon as novel adsorbent

The proposed research describes the synthesis and characterization of platinum nanoparticles loaded on activated carbon (Pt-NP-AC) and its efficient application as novel adsorbent for efficient removal of reactive orange 12 (RO-12). The influences of effective parameters following the optimization of variables on removal percentages, their value was set as 0.015 g Pt-NP-AC, pH 1, contact time of 13 min. At optimum values of all variables at 25 and 50 mgL⁻¹ of RO-12 enthalpy (ΔH⁰) and entropy (ΔS⁰) changes was found to be 59.89 and 225.076, respectively, which negative value of ΔG⁰ shows a spontaneous nature, and the positive values of ΔH⁰ and ΔS⁰ indicate the endothermic nature and adsorption organized of dye molecule on the adsorbent surface. Experimental data was fitted to different kinetic models including first-order, pseudo-second-order, Elovich and intra-particle diffusion models, and it was seen that the adsorption process follows pseudo-second-order model in consideration to intra-particle diffusion mechanism. At optimum values of all variables, the adsorption process follows the second-order kinetic and Langmuir isotherm model with adsorption capacity 285.143 mg g⁻¹ at room temperature.     

One-step microwave synthesis of palladium–carbon nanotube hybrids with improved catalytic performance

A fast and easy one-step linker-free approach for the synthesis of palladium nanoparticle/multiwall carbon nanotube (Pd-NP/MWCNT) hybrid materials is described using microwave irradiation for the effective decomposition of Pd₂dba₃ complex in the presence of MWCNTs. High loadings of Pd nanoparticles (up to 40 wt.%) having sizes between 3 and 5 nm are deposited on the surface of MWCNTs within a time of only 2 min. The Pd-NP/MWCNT materials serve as efficient catalysts in C–C coupling as well as in hydrogenation reactions, all characterized by high conversion rates using a small amount of catalysts, high turnover frequency values and good recyclability.     

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.     

Logit modeling for classification of monocultivar olive oils from southwest Spain: A preliminary study

A characterization study of the main olive oil cultivars of southwest Spain (Picual, Arbequina, and Verdial) has been performed in order to establish logistic regression models. Several quality characteristics (free acidity, peroxide value, K₂₃₂, K₂₇₀, oxidative stability index) and chemical data (fatty acids, sterols, erythrodiol–uvaol composition) were measured. Logit regressions were used to evaluate the correlation of the parameters and to create models that allow saving costs on identifying oils as Arbequina, Picual, or Verdial type. Multiple logit regression models were developed: one for Arbequina, three models for Picual, and two models for Verdial cultivar, allowing in this way to minimize the cost for classifying oil samples. Practical application: The olive oil marketing is increasingly focused on the chemical differentiation and characterization of the product because the chemical composition of these virgin oils is responsible for their valuable sensory and nutritional properties. Here we present a characterization study (quality characteristics and chemical data) from the main olive oil cultivars of southwest Spain, Picual, Arbequina, and Verdial, as a first step for the traceability of these three types of monocultivar virgin olive oils. The results may be used as a training to create models for other olive oil cultivars.     

Colour assays: An inside look into Alentejo traditional limewash paintings and coloured lime mortars

A series of colour assays were conducted taking into account old bibliographic recommendations and oral testimony regarding traditional lime painting technology from the Alentejo (South Portugal) region. The main objectives were: (a) the colorimetric analysis of paintings made with different limewash preparation methods; (b) the comparison between natural processed red and yellows ochre pigments (“home made” and from industrial origin) and synthetic iron oxides in different concentrations and lime proportions; (c) the evaluation of the colorimetric CIELAB coordinates during the lime carbonation process in coloured mortars and limewashes. The results shows that the evolution of L*, a*, and b* during the carbonation process is independent of pigment concentration and paint thickness but dependent of pigment composition and finishing technique (lime painting or coloured mortar). They also emphasize the importance of surface appearance attributes and its influence on the colorimetric parameters. © 2010 Wiley Periodicals, Inc. Col Res Appl, 36, 61–71, 2011     

Purity,quality and stability of Argentinean virgin olive oils

In this paper we evaluate the stability, purity and regulated quality composition of fatty acids and sterols (both physico‐chemical and sensory) of commercial Argentinean virgin olive oils in order to evaluate their acceptance on the world market. For this purpose, samples of the best known and most widely distributed oils in supermarkets located in Buenos Aires (Argentina) were acquired. After thoroughly analysing these samples, only 20% were considered to have an acceptable quality. However, some were excluded because of their high campesterol content, which could be an intrinsic characteristic of these oils. The most useful analytical parameter used to confirm authenticity was ECN‐42 R – ECN‐42 T, followed by wax content and 3.5 stigmastadienes. Only 24% of the extra‐virgin olive oil samples were classified as ‘extra‐virgin’ from the regulated quality viewpoint. The low oleic and high linolenic acid contents of the Argentinean virgin olive oils stand out when compared with European virgin olive oils. The oxidative stability values may be considered very low, indeed even lower than those obtained in Spanish virgin olive oils.     

Ionic conductivities and high resolution microscopic evaluation of grain and grain boundaries of cerium-based codoped solid electrolytes

Doped CeGdO and codoped CeGdOSmO compositions were synthesized, giving rise to nanoparticulate powders. Ionic conductivities at bulk and grain boundaries of the sintered samples were determined, exhibiting increased conductivity in the samaria-codoped samples. Scanning electron microscopy (SEM) showed a significant reduction in the grain size of samaria-codoped electrolytes. This reduced grain size of the codoped samples caused a reduction in Schottky barrier height, increasing oxygen vacancy concentration in the space-charge layer of the grain boundary and culminating in greater ionic conductivity in the boundary region. For the gadolinium doped samples, high resolution transmission electron microscopy images at grains showed the presence of large cluster of defects (nanodomains), hindering the movement of charge carriers and reducing ionic conductivity. However, the samaria-codoped system displayed better homogeneity at atomic level, resulting in reduced oxygen vacancy ordering and, consequently, smaller nanodomains and higher bulk (grain) conductivity. The reduced grain sizes and smaller nanodomains caused by codoping favor the ionic conductivity of ceria-based ceramics, doped with gadolinia and codoped with samaria.