Use Of Polyols Research Articles

Influences of entrainers to engine oil to improve the drag-out of biodiesel – Experiments and simulations

Diesel engines equipped with Diesel Particulate Filters (DPF) suffer from the carry-over of fuel into the engine oil that causes oil dilution. Oil dilution can lead to a decreased oil performance and oil durability. Diesel fuel slowly evaporates out of the engine oil, and does not remain in the oil pan. Compared to diesel fuel, biodiesel remains nearly completely in the engine oil, and leads to a constant engine oil dilution. Furthermore, biodiesel is able to react with the engine oil that can lead to formation of oil sludge, which can result in severe engine damage. The common strategy, which solves those problems, is the reduction of the oil drain interval that leads to increased engine oil consumption.We introduce a method to remove biodiesel from the engine oil by use of an entrainer in order to extend the oil drain interval. Fourteen blends of biodiesel, engine oil and entrainer were distilled, and the distillate was analyzed by gas chromatography and mass spectroscopy for quantitative amount of biodiesel. The influence of polar hydroxyl groups, the dipole moment and the chemical structure of fourteen entrainers to the drag-out of biodiesel were compared. In addition, we analyzed the activity coefficient of the entrainers used with biodiesel, and its influence of the amount of removed biodiesel as well as we determined the present interactions between entrainer and biodiesel. Furthermore, the measured activity coefficients were simulated by a quantum chemical method to compare the experimental results for consistence and analyze the possibility to predict the interaction of entrainer and biodiesel.The results show the drag-out of biodiesel from the engine oil at temperatures of 160°C and 180°C by use of polyols and acids. Mono- and bivalent alcohols yield no drag-out. The number of the hydroxyl groups or the dipole moment of the entrainer does not correlate with removed biodiesel. Acids showed the highest ability for the drag-out of biodiesel (2.3% (m/m) in total for formic acid) and showed the strongest interaction with biodiesel (for formic acid). According to the results, this strong interaction is mainly formed by hydrogen bonds. Furthermore, biodiesel turns out to be a good hydrogen bond acceptor and can be removed by substances that are hydrogen bond donators (e.g. acids, polyols).

A comparative study on poly(xylitol sebacate) and poly(glycerol sebacate): mechanical properties, biodegradation and cytocompatibility

In order to develop degradable elastomers with a satisfactory combination of flexibility and enzyme-mediated degradation rate, the mechanical properties, enzymatic degradation kinetics and biocompatibility of poly(xylitol sebcate) (PXS) has been systematically investigated in comparison with poly(glycerol sebacate) (PGS). Under the same level of crosslinked density, the PXS elastomer networks have approximately twice the stretchability (elongation at break) of their PGS counterparts. This observation is attributable to the relatively longer and more orientable xylitol monomers, compared with glycerol molecules. Although xylitol monomers have two more hydroxyl groups, we, surprisingly, found that the hydrophilic side chains did not accelerate the water attack on the ester bonds of the PXS network, compared with their PGS counterpart. This observation was attributed to a steric hindrance effect, i.e. the large-sized hydroxyl groups can shield ester bonds from the attack of water molecules. In conclusion, the use of polyols of more than three –OH groups is an effective approach enhancing flexibility, whilst maintaining the degradation rate of polyester elastomers. Further development could be seen in the copolymerization of PPS with appropriate thermoplastic polyesters, such as poly(lactic acid) and polyhydroxyalkanoate.

Use of polyols as particle size and shape controllers: application to boehmite synthesis from sol–gel routes

Polyols were successfully used as size and shape controllers of oxide nanoparticles synthesized by soft chemistry in aqueous solution. The efficiency of acyclic polyols as a complexing agent depends obviously on the number of OH groups bonded to the carbon chain (and thus on the carbon chain length), but also on their stereochemistry. This innovating way to control morphology has been experienced for the synthesis of boehmite nanoparticles, whose morphology variations related to xylitol adsorption (C5 alditol) have been previously reported. The use of polyols during synthesis causes a modification of the usual morphologies observed, specifically resulting in an increase of (101) faces area. It is evidenced here that the variations of the nanoparticle aspect ratio are related to polyol complexing ability, and more specifically to molecule topology and configuration. Indeed, the morphology variations increase as a function of polyol carbon chain length and number of hydroxyl groups, and is much pronounced for stereoisomers exhibiting hydroxyl groups all oriented on the same side of the molecule (threo-threo sequences). Thanks to these various polyols used, we showed how the progressive levels of complexing ability allow us to tune boehmite particle size and shape. Material characterizations were performed using relevant methods such as X-ray diffraction powder pattern simulation and zetametry in addition to transmission electron microscopy. Since γ-alumina is obtained from boehmite by a topotactic transformation, we expect that this method will provide a promising way to control surface properties of γ-alumina, an important industrial catalyst support.

Effect of sweet solutes and potassium sorbate on the thermal inactivation of Z. bailii in model aqueous systems

The effect of solute type (glucose and polyols) and potassium sorbate (KS) on Zygosaccharomyces bailii thermal inactivation was evaluated in acidified aqueous model systems. Thermal inactivation curves obtained were fitted with Baranyi equation and parameters of this model were estimated and used to establish the effect of water activity ( a w), solute added and KS on Z. Bailii survival. Results obtained showed that addition of KS (0.025%, w/w) in general promoted an increase in the rate of heat inactivation. The use of polyols to depress a w to 0.985 in the absence of KS produced no effect on rate of heat inactivation. On the contrary, the use of glucose (10%, w/w) enhanced it. This trend was also observed when a w was depressed to 0.971 by glucose or xylitol or glucose-polyols. Moreover, a w depression in systems containing KS produced different effects on thermal inactivation rate depending on system composition. A synergic effect on the rate of inactivation of Z. bailii was observed by the combined use of KS and sorbitol, xylitol or glucose to depress a W to 0.985–0.988. This behavior might allow to decrease the severity of the thermal treatment with no detrimental effect on sterility.

Effect of several humectants and potassium sorbate on the growth of Zygosaccharomyces bailii in model aqueous systems resembling low sugar products

The effect of solute type (glucose and polyols) and potassium sorbate (KS) level on the growth of Zygosaccharomyces bailii was evaluated in model aqueous systems resembling low sugar products. Growth curves were modeled using Gompertz equation. Parameters of the models were estimated and applied to analyze the effect of water activity ( a w), solute used and KS on growth of Z. Bailii. It was observed that as KS concentration increased, the yeast growth diminished gradually. Use of polyols in the absence of KS generally decreased growth. In particular, xylitol was the solute that promoted the highest decrease in yeast growth. Depression of a w in the presence of KS produced different effects on growth rate depending on a w level, solute added and concentration of the preservative. In several cases, a synergism between humectants (glucose and polyols) and KS was observed in relation to growth inhibition. This behavior would allow to maintain the biological activity of the preservative diminishing the amount used.

Sugar Alcohols, Salt Stress, and Fungal Resistance: Polyols—Multifunctional Plant Protection?

The traditional use of polyols as osmotica in plant culture media is based on the assumption that polyols are not taken up or metabolized by cells. In reality, polyols are significant photosynthetic products and efficiently utilized metabolites in a large number of plants. In addition to these metabolic roles, initial interest in polyols focused primarily on their function as osmoprotectants. This was hypothesized to be due to their ability to act as compatible solutes. More recent research, however, indicates much broader roles for polyols in stress responses based on their significant antioxidant capacity. These include protection against salt and photooxidative stress as well as a potential role in plant pathogen interactions.

Influence of Additives on High Pressure Stability of β-Galactosidase from Kluyveromyces Lactis and Invertase from Saccharomyces Cerevisiae

High pressure denaturation of two yeast enzymes, Kluyveromyces lactis β-galactosidase and Saccharomyces cerevisiae invertase in aqueous solutions of salts and polyols was investigated. Polyols (more than salts) were shown to act as very effective agents against pressure denaturation for both enzymes, leading to an increase in half-lives by factors between 1–10,000. NaBr and KBr were essentially destabilizing compounds, leading to protective effects near zero in the case of β-galactosidase. The maximum stability was obtained when KCl was used as additive. The β-galactosidase half-life is increased by a factor of 60 in a 3 m KCl solution and the invertase half-life by a factor of 40. Whereas NaCl had no stabilizing effect on β-galactosidase up to 2 m, this salt was of greater efficiency for invertase whatever the concentration, leading to a protective effect of almost 30 at 3 m. The use of polyols (glycerol, erythritol, xylitol, and sorbitol) allows β-galactosidase and invertase to be stabilized against pressure deactivation. This stabilizing effect increases with the polyol concentration. For invertase in the presence of xylitol, the half-life is increased by a factor of 7 at 1 m and by a factor near 50 at 2 m. The increase in pressure resistance due to the presence of polyols was always greater with β-galactosidase than with invertase. The protective effect of a 2 m xylitol solution is above 10,000 for β-galactosidase whereas it is about 50 for invertase. After the systematic study of the influence of salts and polyols, certain hypotheses are advanced on the possible mechanisms by which additives stabilize proteins to pressure denaturation.

Physical, chemical, and histologic changes in dentin caries lesions of primary teeth induced by regular use of polyol chewing gums

A previous clinical trial showed that long-term use of saliva-stimulating polyol (xylitol and sorbitol) chewing gums was associated with arrest of dental caries in young subjects. After a 20-22-month intervention (when the subjects were 8 years old), a total of 23 primary teeth with extensive dentin caries lesions whose surfacein clinical examination was found to be totally rehardened (remineralized) could be removed because the teeth were near their physiologic exfoliation time. These teeth were subjected to histologic, microhardness, and electron microscopic tests. The majority of the specimens had been remineralized from the surface by a non-cellular-mediated process within the remaining collapsed, organic extracellular matrix associated with the remaining dentinal surface. Many of the underlying dentinal tubules were filled with a matrix that had been subsequently mineralized. Dental microanalyses showed that the topmost (outer) 20-mm-thick rehardened layer of the lesions exhibited the highest Ca:P ratio, which leveled off at a depth ofapproximately 150 mm. The rehardened surface layer (normally <0.1 mm in thickness) was significantly (P < 0.001) harder than sound dentin and nearly as hard as sound enamel. Although the main source of the mineral present in the rehardened layer was most likely of salivary origin, some extracellular remineralization was probably mediated by odontoblasts. The results complete the clinical diagnoses ofthe original trial and suggest that regular use of polyol chewing gums may induce changes in dentin caries lesions, which in histologic and physiochemical studies show typical characteristics of rehardening and mineralization.

A low-temperature-liquifying medium for growth and fruiting of Coprinus congregatus

The use of a low-temperature-liquifying material, Pluronic Polyol F-127, permits the isolation of mycelia of Coprinus congregatus and other fungi from semisolid media with no damage to the fungal cells. Cultures gelled with polyol display the same enzyme patterns as agar-grown cultures and not the patterns of liquid-grown cultures. The use of polyol allows the harvesting of clean mycelia for protoplasting, whereas agar inhibits protoplasting. This procedure is of value in the harvesting, protoplasting, and/or extraction of mycelia that display different biochemical or genetic expression on solid as opposed to liquid media.

Use of polyols to measure equilibrium relative humidity

SummaryPolyols were used to estimate the equilibrium relative humidity (ERH) of foods. Glycerol, ethylene glycol and propylene glycol were found to be suitable for estimating ERH, up to an ERH of 93%, by measuring the refractive index after they had equilibrated in the headspace of a food. The ERH determined by the polyol method agreed with the ERH determined using Sina and Vaisala meters to within 1% ERH for a lithium sulphate slurry, and for foods were usually within 2%. The ERH of prunes determined using the Vaisala meter was about 6% lower than the value obtained by the other methods. Unlike most electronic techniques the polyol method was unaffected by the presence of glycerol, propylene glycol or butylene glycol and so is suitable for measuring the ERH of foods containing these humectants. The polyol method can be used in developing countries where access to sophisticated equipment is limited.

Use of polyols as stationary phases for the gas chromatographic separation of volatile compounds from excess amounts of ethanol

Erythritol, ribitol, arabitol, xylitol, mannitol, dulcitol and sorbitol were studied as stationary phases for the separation of volatile compounds (“volatiles”) normally present in alcoholic beverages. Excellent separations of most of the volatiles from each other, and especially from the excess amounts of ethanol that are generally present, were obtained with 2- and 5-m glass columns filled with Chromosorb P coated with a polyol. A method is presented that permits the analysis of beer volatiles, from acetaldehyde up to phenethyl alcohol, in about 90 min. This method includes the direct injection of beer samples into the columns. After several months, no perceptible changes in column performance were observed; indicating that a rapid and cheap method for the analysis of beer volatile is now available. Wines and spirits have been analyzed by the same method.