Prediction of crude sunflower oil deterioration after seed drying and storage processes

The effects of air-drying temperature and storage time on several characteristics of crude sunflower oil were evaluated in terms of FFA and PV. Long storage affected oil content to a greater extent than air-drying temperature. FFA and PV varied between 0.53 and 1.22% and between 10.7 and 23.3. meq O₂/kg, respectively, when samples of uniform initial moisture content (approximately 28%) were dried at various temperatures between 25 and 90°C to approximately 7% moisture content, stored for 8 mon, and then analyzed. Both oil quality characteristics increased exponentially with air-drying temperature (T) and linearly with storage time (t). Mathematical functions of the form A·exp(B·T)+C·t (where A, B, and C are parameters adjusted from experimental data) most closely predicted the experimental loss of quality of sunflower oil in terms of FFA and PV with variations in T and t. Statistical analysis showed SE of the estimated parameters of 0.08 and 1.19 and coefficients of determination, R ², of 0.922 and 0.939 for FFA and PV, respectively, which were significant at 95% confidence. High-oleic seeds from a similar experiment were used to validate the proposed equation. The results of applying the mathematical function proposed above showed a reasonable ability to predict the experimental values with SE of 0.037 and 0.808 and R ² of 0.983 and 0.972 for FFA and PV, respectively, which were significant at 95% confidence. Plots of residuals showed random distribution. The results obtained suggested that the equation proposed could be used as a quality-loss model in sunflower drying simulations.     

Recovery of phytosterols from sunflower oil deodorizer distillates

Phytosterols are usually recovered by crystallization from the deodorizer distillate (DD) of vegetable oils. In this work, the impact of the principal process variables (viz., solvents and cosolvents, cooling rate, crystallization temperature, and ripening time) on the quality and yield of the recovered phytosterols was studied by using a sunflower oil DD “enriched” (i.e., preconcentrated) via transesterification with ethanol (EDD) as a feedstock and commercial hexane as solvent (S), with S/EDD mass ratios of 3 to 5. Water (0 to 4.5 wt%) and ethanol (0 to 10 wt%) were used as cosovents, with crystallization temperatures between 0 and −20°C and crystallization times from 4 to 96 h. The cooling rate was either −20°C/h or “brisk chilling” from 40 to −5°C. The nature and composition of the EDD solvent and cosolvent composite arose as the most important process variable, strongly influencing both the percentage of sterol yield and the purity of the crystals, as well as their filterability and washability. Water-saturated hexane sufficed to give good crystallization, yet the beneficial effect of adding water as the single cosolvent was enhanced by adding small and precise amounts of ethanol. A recovery of sterols as high as 84% (with 36% purity) was achieved by using a single-stage batch crystallization of the S/EDD mixture (S/EDD=mass ratio 4).     

Gas‐Liquid Mass Transfer Rates and Impeller Power Consumptions for Industrial Vessel Design

Volumetric mass transfer coefficients (k_La) and power input (P) are often the key parameters in the design of gas‐liquid contactors. However, due to the limitations of most measurement methods, there is a lack of reliable data for predicting k_La for non‐coalescent batches under high energy dissipation rates. Accurate k_La and P correlations are proposed. The reliability of the correlations is ensured by using experimental data from a wide range of process conditions conducted in multiple‐impeller vessels of both laboratory scale and pilot scale, and including both non‐coalescent and coalescent batches. Applying the proposed correlations, the scale‐up and optimization of industrial vessels can be performed more accurately.     

Synthesis and Evaluation of Novel Acyclic Nucleoside Phosphonates as Inhibitors of Plasmodium falciparum and Human 6‐Oxopurine Phosphoribosyltransferases

Acyclic nucleoside phosphonates (ANPs) are a promising class of antimalarial therapeutic drug leads that exhibit a wide variety of K_i values for Plasmodium falciparum (Pf) and human hypoxanthine‐guanine‐(xanthine) phosphoribosyltransferases [HG(X)PRTs]. A novel series of ANPs, analogues of previously reported 2‐(phosphonoethoxy)ethyl (PEE) and (R,S)‐3‐hydroxy‐2‐(phosphonomethoxy)propyl (HPMP) derivatives, were designed and synthesized to evaluate their ability to act as inhibitors of these enzymes and to extend our ongoing antimalarial structure–activity relationship studies. In this series, (S)‐3‐hydroxy‐2‐(phosphonoethoxy)propyl (HPEP), (S)‐2‐(phosphonomethoxy)propanoic acid (CPME), or (S)‐2‐(phosphonoethoxy)propanoic acid (CPEE) are the acyclic moieties. Of this group, (S)‐3‐hydroxy‐2‐(phosphonoethoxy)propylguanine (HPEPG) exhibits the highest potency for PfHGXPRT, with a K_i value of 0.1 μM and a K_i value for human HGPRT of 0.6 μM . The crystal structures of HPEPG and HPEPHx (where Hx=hypoxanthine) in complex with human HGPRT were obtained, showing specific interactions with active site residues. Prodrugs for the HPEP and CPEE analogues were synthesized and tested for in vitro antimalarial activity. The lowest IC₅₀ value (22 μM ) in a chloroquine‐resistant strain was observed for the bis‐amidate prodrug of HPEPG.     

Describing the sorption characteristics of a ternary system of benzene (1) and alcohol (2) in a nonporous polymer membrane (3) by the Flory–Huggins model

The Flory–Huggins equation was used to describe results of total and preferential sorption measurements for the binary liquid mixture of benzene (1) and alcohol (2) in one of two nonporous polymer membranes (3), low‐density polyethylene (LDPE) and Nafion membrane. The concentration dependence of binary and ternary interaction parameters was determined. The interaction parameters for the benzene – methanol binary mixture were obtained from binary vapor‐liquid equilibrium data in the literature to decrease the number of adjusted parameters. The results show that use of a ternary interaction parameter is necessary. Data treatment was performed assuming either no crystallinity or an average crystallinity typical for the studied membranes. Subsequently, the limiting activity coefficients of solutes in LDPE were calculated from the values of the interaction parameters and their values compared to values of the limiting activity coefficients of benzene and methanol in hypothetical liquid alkane with the same density as LDPE obtained by the UNIFAC method. POLYM. ENG. SCI., 55:1187–1195, 2015. © 2014 Society of Plastics Engineers     

Insight into the Interaction Between Carbopol® 940 and Ionic/Nonionic Surfactant

Mixtures of a cross‐linked polyacrylic acid (Carbopol^® 940) and two types of surfactants, namely anionic sodium dodecylsulfate (SDS) and nonionic Tween^® 80, were investigated by viscometry, conductometry, tensiometry, spectrophotometry, fluorimetry and scanning electron microscopy (SEM). The addition of nonionic surfactant decreased the reduced viscosity and the transmittance of the Carbopol^® polymer aqueous solutions. Furthermore, the interaction between Carbopol^® 940 and SDS was characterized by two significant concentration values: the critical aggregation concentration of SDS was particularly independent of Carbopol^® polymer concentration while the polymer saturation point of both surfactants increased with the increase in polymer content. The values of critical aggregation concentration and polymer saturation point obtained using various techniques confirmed the occurrence of Carbopol^® polymer–surfactant associations. The effect of different SDS and Tween^® 80 concentrations on the conformation of Carbopol^® 940 in aqueous solution could be explained through hydrophobic association between surfactant micelles and Carbopol^® polymer tails and through hydrogen bonding in the case of Tween^® 80. Additionally, the surfactant‐induced structural changes were confirmed in Carbopol^® 940–SDS and Carbopol^® 940–Tween^® 80 aqueous solutions by SEM measurements.     

Polymerase Synthesis and Restriction Enzyme Cleavage of DNA Containing 7‐Substituted 7‐Deazaguanine Nucleobases

Previous studies of polymerase synthesis of base‐modified DNAs and their cleavage by restriction enzymes have mostly related only to 5‐substituted pyrimidine and 7‐substituted 7‐deazaadenine nucleotides. Here we report the synthesis of a series of 7‐substituted 7‐deazaguanine 2′‐deoxyribonucleoside 5′‐O‐triphosphates (dG^RTPs), their use as substrates for polymerase synthesis of modified DNA and the influence of the modification on their cleavage by type II restriction endonucleases (REs). The dG^RTPs were generally good substrates for polymerases but the PCR products could not be visualised on agarose gels by intercalator staining, due to fluorescence quenching. The presence of 7‐substituted 7‐deazaguanine residues in recognition sequences of REs in most cases completely blocked the cleavage.     

Water‐blown polyurethane/polyisocyanurate foams made from recycled polyethylene terephthalate and liquefied wood‐based polyester polyol

Depolymerized polyethylene terephthalate and liquefied wood polyesters can be used as a polyol for the production of polyurethane/polyisocyanurate foams. In this research, liquefied wood was synthesized by using a combination of diethylene glycol and glycerol and due to the possibility of using glycerol that is a by‐product in biodiesel production, our goal was to use as much glycerol in the liquefaction reagent as possible. We determined the properties of the polyols, properties of produced foams, and explained their correlation. Greater amount of glycerol in the liquefaction reagent resulted in higher OH number, molecular weight, functionality, and viscosity of the polyol, as well as in longer cream time and tack free time in foam preparation. Glass transition temperature, density, and water absorption of the foam increased with increasing amount of glycerol in liquefied wood. Compressive stress increased up to 30% of the glycerol in the reagent and then reduced, while thermal conductivity was not affected. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41522.     

Effects of mechanical-activation and TiO2 addition on the behavior of two-step sintered steatite ceramics

Steatite, as ceramic with composition predominantly resting on magnesium silicate, was produced from economic resources – talc, aluminosilicate clays, and either BaCO₃ or feldspar as flux. Titanium dioxide was a doping agent. Four steatite mixtures were mechanically activated in a planetary ball mill for 30, 45 or 60?min, prior to the thermal treatment. Two-step sintering with initial phase set at 1350?°C and holding period conducted at 1250?°C was applied to initiate diffusion and prevent grain growth. Thereby, a high density ceramic material with low-porous submicron structure was acquired. The effects of TiO₂ addition on densification, microstructure, and dielectric characteristics of steatites were monitored. The thermal stability of green mixtures was tested by differential thermal and thermogravimetric analyses. Changes in crystallinity and mineral phase composition were observed by the X-ray diffraction technique. Microstructural visualization with spatial arrangements of individual chemical elements on surface of the sintered ceramics was acquired by scanning electron microscopy accompanied with EDS mapping. In order to test the possibility of employment of the obtained steatites in insulation materials, electrical measurements were conducted by recording variations of the dielectric constant and loss tangent as a function of alternations in the mix-design and the mechanical activation period.