Preparation and characterization of polyurethane foams using a palm oil-based polyol

Polyurethane (PU) foams were prepared using a palm oil-based polyol (PO-p). At the first stage, palm oil was converted to monoglycerides as a new type of polyol by glycerolysis. A yield of the product reached 70% at reaction temperature of 90 degrees C by using an alkali catalyst and a solvent. At the second stage, PU foams were prepared from mixtures of the polyol and polyethylene glycol (PEG) or diethylene glycol (DEG) and an isocyanate compound. Characterization of the foams was carried out by thermal and mechanical analyses. The analyses showed that the chain motion of polyurethane becomes more flexible at the higher PO-p content in the whole polymer, which indicates that the monoglyceride molecules work as soft segments. The study here may lead to a development of a new type of polyurethane foams using palm oil as a raw material.     

Physical properties of canola oil based polyurethane networks

A new generation polyol (generation-II) with significantly higher triol content and higher hydroxyl value was synthesized from canola oil by introducing a mild solvent (ethyl acetate) and a more efficient reductive reagent (zinc) to the previous synthetic procedure (Narine, S. S.; Yue, J.; Kong, X. J. Am. Oil Chem. Soc. 2007, 84, 173-179). Polyurethane (PUR) elastomers were prepared by reacting this type of polyol with aliphatic diisocyanates. The physical and thermal properties of the PUR elastomers were studied using dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC) and compared to the elastomers made from the old generation polyol (generation-I). The concentration of elastically active network chains (nue) of the polymer networks was calculated based on rubber elasticity theory. Larger nue and narrower distribution of nue was observed in the case of the PURs prepared from the generation-II polyol. The relatively faster relaxation at higher temperature for this type of PUR elastomer, suggests a tighter cross-linked network structure by reducing the dangling chains effect. With the same OH/NCO molar ratio, the PURs prepared from the generation-II polyol showed higher glass transition temperatures (Tg), higher Young's modulus and tensile strength, and longer elongation at break.     

The identification of phosphorylated neo-inositol as an anionic component of the Amoeba cell surface

A nonreducing polyol, previously called pre-mannose [Allen et al. (1974) J. Cell Biol.60, 26–38], present in the isolated cell surface of Amoeba has been identified as neoinositol. The polyol was present on the cell surface as a highly phosphorylated but nonpolymerized phosphate ester. Cold acid extraction of Amoeba homogenates and alkaline precipitation of the acid-soluble fraction gave a preparation containing the polyol as the major neutral sugar residue. The polyol was identified by gas-liquid chromatography and mass spectrometry of its trimethylsilyl ether and acetate ester derivatives. The acid-labile phosphate ester present in isolated surface fractions was found to be separable from the acid-stable phosphate ester. Current data indicated that the labile phosphate was polyphosphate.     

Antimonite is accumulated by the glycerol facilitator GlpF in Escherichia coli.

In a search for genes responsible for the accumulation of antimonite in Escherichia coli, TnphoA was used to create a pool of random insertional mutants, from which one antimonite-resistant mutant was isolated. Sequence analysis showed that the TnphoA insertion was located in the glpF gene, coding for the glycerol facilitator GlpF. The mutant was shown to be defective in polyol transport by GlpF. These results suggest that in solution Sb(III) is recognized as a polyol by the glycerol facilitator.     

Losses of Polyol through Leaching in Subarctic Lichens

Upon rewetting, lichens lose polyols through leaching. We quantified leaching losses for 21 species under simulated rainfall. Polyol concentrations in these lichens range from 1.0 to 8.8%, with a mean of 2.8%. Leaching losses range up to about 7.5 mg (polyol)/g (lichen dry weight) in a typical rain event. The rate of polyol leaching declines exponentially, becoming negligible within 1 hour of continuous rain. The response of polyol leaching rate to rainfall intensity and amount varies between species—six species showed no response, one had increased leaching with increased rainfall intensity, four had increased leaching with increased amount of rainfall, and one had decreased leaching with increased total amount of rainfall. Polyol leaching rates are positively correlated with polyol concentration for 20 species. Literature values of average daily growth rates for subarctic lichens are of the same order of magnitude as leaching rates, suggesting that polyol leaching is an important part of the carbon budget of lichens.     

An Alternative Gelling Agent for Culture and Studies of Nematodes,Bacteria, Fungi,and Plant Tissues

Pluronic F127 polyol, a block copolymer of propylene oxide and ethylene oxide, was studied as an alternative to agar in culture media for nematodes, bacteria, fungi, actinomycetes, and plant tissues or seedlings, At a polyol concentration of 20% w/v, the culture media, semi-solid at room temperature (22 C) but liquid at lower temperatures, had minimal effects on the test organisms. Most of the fungi and bacteria grew as well in 20% polyol as in 1.5% agar media; however, various species of nematodes and plant seedlings or tissues exhibited differential sensitivities to different concentrations of the polyol. In cases where the organisms were unaffected, the polyol media had certain advantages over agar, including greater transparency and less contamination under nonaseptic conditions. Polyol media have potentially greater ease for recovery of embedded organisms or tissues inside the media by merely shifting to lower temperatures.     

The study of diabetic cataractogenesis in the intact rabbit lens by deuterium NMR spectroscopy

The polyol pathway has been implicated in the process of diabetic cataractogenesis. We report the use of deuterium (2H) spectroscopy for dynamically monitoring the polyol and glycolytic pathways in the single intact rabbit lens. Using 2H labeled C-1 D-glucose, the formation of sorbitol from glucose and the metabolism of sorbitol to fructose was dynamically monitored at 5.5 mM and 35.5 mM glucose concentrations. The accumulation of sorbitol at 35.5 mM glucose concentration was prevented by the inhibition of aldose reductase using an inhibitor (Sorbinil). 2H spectra were obtained in short acquisition times because of the short T1's of deuterated metabolites. A further advantage of 2H spectroscopy is that the natural abundance resonance of water (HDO) can be used as an internal reference standard. These findings confirm previous studies and demonstrate for the first time by NMR spectroscopy activity in the polyol pathway at low glucose concentrations.     

Microbial Water Relations: Features of the Intracellular Composition of Sugar-Tolerant Yeasts

Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast. One such factor was the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism. In such cases (lactose and glycerol), the sugar-tolerant species had a much lower capacity for the solute than did the nontolerant species. Sucrose uptake was consistently different between all sugar-tolerant strains on the one hand and all nontolerant strains on the other. The difference was attributable in part to metabolism of sucrose by the nontolerant yeasts. The major difference between the two types of yeast, however, was the presence of one or more polyhydric alcohols at high concentrations within each of the sugar-tolerant strains but none of the nontolerant strains. In most cases the major polyol was arabitol. The solute concentration (and, hence, water availability) of the growth medium affected both the amount of arabitol produced by Saccharomyces rouxii and the proportion retained by the yeast after brief washing with water at 0 C. When the yeast was suspended in a buffer at 30 C, the polyol leaked out at a slow, constant, reproducible rate. The polyene antibiotic amphotericin B caused rapid release of polyol by the yeast, the rate being proportional to amphotericin concentration. Contact of the yeast with glucose (1 mM) caused an extremely rapid ejection of polyol which lasted less than 40 s. Some implications of these results are discussed, as is the role of the polyol as a compatible solute in determining the water relations of the yeast.     

The conservation of polyol transporter proteins and their involvement in lichenized Ascomycota

In lichen symbiosis, polyol transfer from green algae is important for acquiring the fungal carbon source. However, the existence of polyol transporter genes and their correlation with lichenization remain unclear. Here, we report candidate polyol transporter genes selected from the genome of the lichen-forming fungus (LFF) Ramalina conduplicans. A phylogenetic analysis using characterized polyol and monosaccharide transporter proteins and hypothetical polyol transporter proteins of R. conduplicans and various ascomycetous fungi suggested that the characterized yeast’ polyol transporters form multiple clades with the polyol transporter-like proteins selected from the diverse ascomycetous taxa. Thus, polyol transporter genes are widely conserved among Ascomycota, regardless of lichen-forming status. In addition, the phylogenetic clusters suggested that LFFs belonging to Lecanoromycetes have duplicated proteins in each cluster. Consequently, the number of sequences similar to characterized yeast’ polyol transporters were evaluated using the genomes of 472 species or strains of Ascomycota. Among these, LFFs belonging to Lecanoromycetes had greater numbers of deduced polyol transporter proteins. Thus, various polyol transporters are conserved in Ascomycota and polyol transporter genes appear to have expanded during the evolution of Lecanoromycetes.     

Polyol metabolism by Rhizobium trifolii.

In Rhizobium trifolii 7000, the polyols myo-inositol, xylitol, ribitol, D-arabitol, D-mannitol, D-sorbital, and dulcitol are metabolized by inducible nicotinamide adenine dinucleotide-dependent polyol dehydrogenases. Five different polyol dehydrogenases were recognized: inositol dehydrogenase, specific for inositil; ribitol dehydrogenase, specific for ribitol; D-arabitol dehydrogenase, which oxidized D-arabitol, D-mannitol, and D-sorbitol; xylitol dehydrogenase, which oxidized xylitol and D-sorbitol; and dulcitol dehydrogenase, which oxidized dulcitol, ribitol, xylitol, and sorbitol. Apart from inositil and xylitol, all of the polyols induced more than one polyol dehydrogenase and polyol transport system, but the heterologous polyol dehydrogenases and polyol transport systems were not coordinately induced by a particular polyol. With the exception of xylitol, all of the polyols tested served as growth substrates. A mutant of trifolii 7000, which was constitutive for dulcitol dehydrogenase, could also grow on xylitol.     

Absolute configuration of a polyol fragment of blasticidin A, a specific inhibitor of aflatoxin production

Blasticidin A (1) and aflastatin A (2), Streptomyces metabolites with similar structures, are specific inhibitors of aflatoxin production by Aspergillus parasiticus. The stereochemistry of the polyol fragment of 1 (3a) containing ten chiral centers was elucidated by applying acetonide and MTPA methods to a variety of acetonide derivatives of 3a, which determined the absolute configuration of 3a. By using the similar methods, the absolute configuration of the polyol fragment of 2 (4a) was determined, which was the same as that elucidated by J-based and other chemical methods previously.     

Comparative lipid composition of heterotrophically and autotrophically grown Sulfolobus acidocaldarius.

Complex lipids from the thermoacidophilic facultative autotroph Sulfolobus acidocaldarius, as well as a strictly autotrophic isolate, were compared between cells grown on yeast extract and elemental sulfur. Lipids from both organisms grown autotrophically were nearly identical. Each contained about 15% neutral lipids, 35% glycolipids, and 50% acidic lipids. Glycolipids and acidic lipids contained C40H82-76-derived glycerol ether residues. Major glycolipids included the glycerol ether analogues of glucosyl galactosyl diglyceride (5%) and glucosyl polyol diglyceride (75%). Acidic lipids were comprised mainly of the glycerol ether analogues of phosphatidyl inositol (7%), inositolphosphoryl glucosyl polyol diglyceride (72%), and a partially characterized sulfate- and phosphate-containing derivative of glucosyl polyol diglyceride (13%). The lipids from cells grown heterotrophically were similar to those from autotrophically grown cells, except that the partially characterized acidic lipid was absent. In addition, the two glycolipids as well as the respective inositolphosphoryl derivatives were each present in nearly equal proportions.     

Some effects of mannitol on the glucose metabolism of two derivatives of a strain ofRhizobium japonicum differing in mannitol dehydrogenase

The effects of mannitol were investigated by comparing some metabolic features in colonial derivatives, I-110 and L1-110, ofRhizobium japonicum strain 3IIb110, grown either on glucose alone (G-cells) or in glucose media supplemented with mannitol (GM-cells). The polyol stimulated the synthesis of not only mannitol dehydrogenase, which is active in derivative L1-110, but also the nicotinamide adenine dinucleotide (NAD)-linked 6-phosphogluconate (6-PG) dehydrogenase (EC 1.1.1.43). As revealed by radiorespirometry, when GM-cells were allowed to metabolize glucose, they produced relatively more CO₂ from the first and sixth carbons of the sugar than G-cells did. This finding is evidence that NAD-linked 6-PG dehydrogenase might initiate an unknown pathway different from the hexose cycle and the pentose phosphate (PP) pathway. Mannitol exerted no allosteric control on the oxygen consumption and the glucose transport systems. Active uptake of the polyol was correlated with the presence of mannitol dehydrogenase (EC 1.1.1.67); it did not hinder the transport of glucose even though both systems derive their energy for active transport from a common source presumptively characterized as the energized membrane state. Mannitol, however, suppressed by two- or threefold the glucose uptake system. Addition of the polyol to the cell suspensions of both colonial types ofR. japonicum metabolizing glucose caused an immediate 40–50% drop of adenosine triphosphate (ATP) concentrations, owing in part to the mannitol kinase reaction. Type I-110 failed to overcome this reduction of ATP levels, and low growth rates could results. In contrast, type L1-110 offsets the reduction of ATP concentration by oxidizing mannitol as an additional source of energy through mannitol dehydrogenase, fructokinase, and a sequence of glycolytic reactions. The polyol also induced type L1-110 to produce extracellular slimy materials that, apparently, harbor amounts of ATP and proteins.     

Structure and properties of polyurethanes prepared from triglyceride polyols by ozonolysis

Ozonolysis was used to obtain polyols with terminal primary hydroxyl groups and different functionalities from trilinolein (or triolein), low-saturation canola oil, and soybean oil. The functionality of the model polyol from triolein (trilinolein) was 3.0 and that of soy polyol was 2.5, due to the presence of unreactive saturated fatty acids, while canola gave a polyol with a functionality of 2.8. All polyols exhibited a high tendency to crystallize at room temperature. The resulting waxes had melting points comparable to that of paraffin and very low viscosities in the liquid state. The polyols were cross-linked using 4,4'-methylenebis(phenyl isocyanate) to give polyurethanes. Glass transitions (T(g)) for the model-, canola-, and soy-based polyurethanes were 53, 36, and 22 degrees C, respectively. The about 30 degrees C lower T(g) of the soy-based polyurethane than that of the model polyurethane was the result not only of lower functionality but also of the presence of saturated fatty acids in the former. Polyurethane from the canola polyol had intermediate cross-linking density and properties. These polyurethanes displayed excellent mechanical properties and higher glass transition temperatures compared to polyurethanes from epoxidized and hydroformylated polyols of the same functionality, presumably due to the absence or lower content of dangling chains in the former.     

Long-Chain Glycerol Diether and Polyol Dialkyl Glycerol Triether Lipids of Sulfolobus acidocaldarius

Cells of Sulfolobus acidocaldarius contain about 2.5% total lipid on a dry-weight basis. Total lipid was found to contain 10.5% neutral lipid, 67.6% glycolipid, and 21.7% polar lipid. The lipids contained C(40)H(80) isopranol glycerol diethers. Almost no fatty acids were present. The glycolipids were composed of about equal amounts of the glycerol diether analogue of glucosyl galactosyl diglyceride and a glucosyl polyol glycerol diether. The latter compound contained an unidentified polyol attached by an ether bond to the glycerol diether. The polar lipids contained a small amount of sulfolipid, which appeared to be the monosulfate derivative of glucosyl polyol glycerol diether. About 40% of the lipid phosphorus was found in the diether analogue of phosphatidyl inositol. The remaining lipid phosphorus was accounted for by approximately equal amounts of two inositol monophosphate-containing phosphoglycolipids, inositolphosphoryl glucosyl galactosyl glycerol diether and inositolphosphoryl glucosyl polyol glycerol diether.     

Metabolism of some polyols by Rhizobium meliloti

The utilization of d-mannitol, d-arabitol, and d-sorbitol by Rhizobium meliloti was studied in extracts from mannitol-grown cells. Two different polyol dehydrogenases were induced by any of these polyols: (i) a nicotinamide adenine dinucleotide (NAD)-arabitol dehydrogenase and (ii) a NAD-sorbitol dehydrogenase, whereas polyol phosphate dehydrogenases were absent. d-Arabitol dehydrogenase was observed to act on both d-arabitol and d-mannitol, but d-sorbitol dehydrogenase acted specifically on d-sorbitol. d-Arabitol was oxidized to d-xylulose, d-mannitol and d-sorbitol were oxidized to d-fructose. An adenosine triphosphate-linked hexokinase which acts on d-fructose and absence of hexose isomerase were also detected in this organism.     

Purification and properties of a polyol dehydrogenase from the phototrophic bacterium Rhodobacter sphaeroides

A polyol dehydrogenase was detected in cell extracts of the facultative phototrophic bacterium Rhodobacter sphaeroides strain Si 4 grown on D-glucitol (sorbitol) as the sole carbon source. The enzyme was purified 150-fold to apparent homogeneity by steps involving fractionated (NH4)2SO4 precipitation, chromatography on Q-Sepharose and phenyl-Sepharose, and FPLC on Superose 12. The relative molecular mass (Mr) of the native polyol dehydrogenase was 47,200 as calculated from its Stokes' radius (rs = 2.76 nm) and sedimentation coefficient (s20, w = 4.15 S). SDS/PAGE resulted in one single band representing a polypeptide with a Mr of 52,200, indicating that the native protein is a monomer. The isoelectric point of the polyol dehydrogenase was determined to be pH 4.3. The enzyme was specific for NAD+ and oxidized both D-glucitol and D-mannitol to D-fructose, as well as D-arabinitol to D-ribulose. The pH optimum of substrate oxidation was pH 9.0 in 0.1 M Tris/HCl and that of substrate reduction was pH 6.5 in 0.1 M potassium phosphate. The reactions exhibited normal Michaelis-Menten kinetics allowing the estimation of KM values for NAD+ (0.18 mM) in the presence of D-glucitol, and for D-glucitol (31.8 mM), D-mannitol (0.29 mM) and D-arabinitol (1.8 mM), respectively. The KM value for D-fructose was 16.3 mM and that for NADH 0.02 mM. The equilibrium constants determined for the conversion of D-mannitol, D-glucitol and D-arabinitol were 4.5 nM, 0.58 nM and 80 pM, respectively. Based on the catalytic preference of the polyol dehydrogenase for D-mannitol, an enzymatic assay for D-mannitol was elaborated.     

Structural features of nonionic polyglycol polymer molecules responsible for the protective effect in sparged animal cell bioreactors.

The nonionic surfactant Pluronic F-68 polyol is commonly used to protect cultured animal cells from the detrimental effects of sparging. In this study we investigated the structural features of the Pluronic F-68 molecule responsible for this protective behavior. Poly(oxyethylene)-poly(oxypropylene) block copolymer polyols of various molecular weights and percentages of hydrophobe (poly(oxypropylene], including both Pluronic and reverse Pluronic polyols, were considered. The potential toxicity of these agents was examined in the absence of sparging (i.e., in spinner flasks) by using the attachment-independent Sf9 insect cell line as a model system. Each polyol resulted in one of three distinct types of behavior in these spinner flask experiments: (1) cells lysed at an exponential rate, (2) inhibition of cell growth (i.e., no net cell growth), or (3) uninhibited cell growth. It was then shown that all of the Pluronic and reverse Pluronic polyols that did not inhibit cell growth provided protection from sparging in the bioreactors used in this study; thus, finding a polyol that protected cells was synonymous with finding one that did not inhibit cell growth. The ability of these polyols to protect animal cells in sparged bioreactors was found to correlate well with the hydrophilic-lipophilic balance (HLB). Those polyols with the largest HLB values were found to be protective agents. These poly(oxyethylene)-poly(oxypropylene) polyols were also shown to be more effective protective agents than pure poly(oxyethylene); thus, the presence of the hydrophobe (poly(oxypropylene] is important in their ability to serve as protective agents.     

Production of extracellular polyols in Aureobasidium pullulans

Aureobasidium pullulans produced extracellularly considerable amounts of polyols in the media with sucrose, glucose, fructose and mannose as sole carbon source during the late exponential and stationary phase of growth. The maximum yield of polyol was about 23% in the 20%(w/v) sucrose medium, of which mannitol was the main polyol associated with minute quantities of glycerol. Stress solutes such as NaCl and KCl did not promote polyol production.