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Prodrug-based nanoassembly emerges as a hopeful way for the efficient delivery of antitumor drugs, with carrier-free structure and ultra-high drug loading. Carbon chains are widely used to design self-assembling prodrugs. The impacts of the length of carbon chains on the self-assembly stability, drug delivery efficiency and antitumor effect of prodrugs have not been fully elucidated. Here, three paclitaxel prodrugs were synthesized by conjugating paclitaxel with octanol (C8), decanol (C10) or dodecanol (C12) through disulfide bond. The three prodrugs could form homogeneous nanoparticles, with over 50% drug loading and redox dual-responsivity. Interestingly, the length extension of carbon chains ameliorates the self-assembly and the colloidal stability of prodrugs, thus improving the drug delivery efficiency. The optimal paclitaxel-dodecanol prodrug nanoassemblies exhibit better antitumor efficacy than Taxol and Abraxane. These findings are meaningful for the rational design of advanced nanomedicines in cancer therapy.

Promoters play an important role in regulating gene expression, and construction of microbial cell factories requires multiple promoters for balancing the metabolic pathways. However, there are only a limited number of characterized promoters for gene expression in the methylotrophic yeast Ogataea polymorpha, which hampers the extensive harnessing of this important yeast toward a cell factory. Here we characterized the promoters of methanol utilization pathway, precursor supply pathway, and reactive oxygen species (ROS) defense system, by using a green fluorescence protein variant (GFPUV) as a quantification signal. Finally, the characterized promoters were used for tuning a fatty alcohol biosynthetic pathway in O. polymorpha and realized fatty alcohol production from methanol. This promoter box should be helpful for gene expression and pathway optimization in the methylotrophic yeast O. polymorpha. KEY POINTS : • 22 promoters related to methanol metabolism were characterized in O. polymorpha. • Promoter truncation resulted shorter and compact promoters. • Promoters with various strengths were used for regulating a fatty alcohol biosynthesis from methanol.

Abstract Coking coal dust is extremely hydrophobic; therefore, combination with droplets in the air is difficult and dust suppression is challenging. Here, a dust suppressant spray for coking coal dust was studied in order to improve of the combination of droplets and coking coal dust. Based on monomer optimization and compounding analysis, two surfactant monomers, fatty alcohol ether sodium sulfate (AES) and sodium dodecyl benzene sulfonate (SDBS) were selected as the surfactant components of the dust suppressant. The surfactant monomers were combined with four inorganic salts and the reverse osmosis moisture absorption of each solution was determined. By combining the reverse osmosis moisture absorption values with the water retention experimental results, CaCl2 was identified as the optimal inorganic salt additive for the dust suppressant. Finally, the optimal concentration of each component was obtained using orthogonal experimental design i.e., AES (0.03%), SDBS (0.05%), and CaCl2 (0.4%). The dust suppressant solution formulated using this method had a high moisture absorption capacity and excellent performance. Graphic Abstract

In this study, a series of gelators (Gn, n is the number of carbon atoms of used fatty alcohol, n = 2, 4, 6, 8, 10, 12, 14, 16 and 18) were synthesized by reacting 4,4′-diphenylmethane diisocyanate with fatty alcohols. Meanwhile, n-octadecane-based gels as form-stable phase change materials (FSPCMs) for thermal energy storage were prepared by introducing Gn into n-octadecane. The gel properties were confirmed by “tube testing method.” The results show that Gn (n = 2, 4) were immiscible with n-octadecane, while a lower mass percentage content (≤ 6 mass%) of Gn (n = 6, 8, 10, 12, 14, 16, 18) can gelate the n-octadecane and the gel-to-sol transition temperature is higher than 100 °C. The chemical structures, morphologies and crystalline properties of prepared FSPCMs were determined by Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction and polarized optical microscope. It is found that Gn could self-assemble into lamellar three-dimensional network structure to restrict the leakage of melted n-octadecane. Differential scanning calorimetry analysis results indicate that prepared FSPCMs exhibit high latent heats and latent heat efficiency is greatly higher than that of other traditional FSPCMs. Moreover, thermal cycling test results confirm that the prepared FSPCMs have good thermal reliability and reusability. This study is attractive for preparation of FSPCMs with high latent heats. Prepared FSPCMs could be potentially applied in the field of thermal energy storage for thermal comfort.

Arelevant task in the technology of cosmetic and pharmaceutical substances is that of protecting the skin from the harmful influences of ultraviolet light - sunburn, photodermatoses, skin cancerogenesis, and light-induced aging. Gels containing N-(β-hydroxyethyl)-4,6-dimethyldihydropyrimidone-2 (xymedone) and amphiphilic components, i.e., nonionic surface-active substances (surfactants), were developed and studied. Aspectrophotometric method was used to study the selective absorption of xymedone in the UV range. Overall, the structural- mechanical characteristics of gels and assessment of the effects of surfactant on xymedone release processes were used to select the optimum composition for effective protection against light by gels. Studies in models of ultraviolet erythema in albino guinea pigs and volunteers receiving prophylactic applications showed that xymedone-containing gel had photoprotective effects. The presence of a hydroxyethylated higher fatty alcohol in the gel composition with xymedone increased its photoprotective activity.

Fatty alcohol biosynthesis by oleaginous microbes was a promising alternative to the petroleum or other non-renewable resources-based process. However, low titer and yield hamper the further industrial and commercial applications. Here, we developed an efficient strategy to coordinate fatty alcohol with glycolysis which achieved a ‘pull-and-push’ effect to improve fatty alcohol production. Transcript profiling indicated that genes in carbohydrate metabolism were up-regulated significantly in response to high fatty alcohol production. Based on it, 11 glycolysis promoters were screening to express fatty acyl-CoA reductase ( FAR ) to relate the fatty alcohol production with the up-regulated carbohydrate metabolism, and the fatty alcohol production reached 557 mg/L when FAR was expressed by the promoter of PFBAin. RNA-seq and qRT-PCR analysis demonstrated that a ‘pull-and-push’ effect caused by the coordination system dynamically enhanced the product synthesis flux from top to bottom, which was also testified and intensified by doubled glucose concentration. After manipulating structural and regulatory genes of lipid metabolism, the final strain achieved up to 5.75 g/L fatty alcohol production from modified YPD medium (containing 91 g/L glucose) in shake flasks, which represented the highest titer reported to date. This work offered a feasible and effective reference for dynamic manipulation of fatty acid-derived chemicals synthesis.

Corrosion of metals is an important economic problem globally. The use of corrosion inhibitors, mainly those based on surfactants, is one of the most efficient ways of defending metal surfaces against corrosion. This study aimed to synthesis some novel ethoxylated and sulfonated fatty alcohol surfactants. The symbols B1, B2, and B3 were pointed to R–CH2O–(CH2CH2O)20–SO3Na, R–CH2O–(CH2CH2O)20–H, and R–CH2O–(CH2CH2O)7–SO3Na, respectively. Spectroscopic methods (FTIR, 1H NMR) were used to characterize the compounds. Micelle concentration (CMC) for the synthesized surfactants was determined and discussed. The surface tension and thermodynamic properties of these inhibitors were investigated. The ability of the synthesized ethoxylated and sulfonated compounds to inhibit the corrosion of C-steel was investigated. Electrochemical, and surface analysis techniques were used to describe the corrosion behavior in blank and inhibiting solutions. Electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PP), and electrochemical frequency modulation (EFM) were used as electrochemical techniques at 25 °C. The inhibition efficiency increases with the concentration. A higher inhibition efficiency among the investigated compounds was at the concentration of 300 ppm from compound B1. The investigated surfactants behave as mixed corrosion inhibitors. It was found that the adsorption process obeys Langmuir isotherm. Adsorption parameters were calculated then explained. The adsorption of the investigated compounds is physisorption. The surface morphology of the C-steel and the formed protective film were examined using SEM. The order of inhibition efficiencies was B1 > B2 > B3. The data obtained from various techniques were in good agreement.

Novel fatty alcohol ethoxylate surfactants (NFAES) C1:(C12–C14–EO30) and C2:(C16–C18–EO30) were synthesized and characterized, and the effect of an increase of the hydrocarbon chain length at the same numbers of ethoxylated groups of these surfactants on the corrosion of mild steel (MS) in 1 M HCl was studied by different methods. These have revealed that the inhibition efficiency (IE%) increases with increasing the dose and the hydrocarbon chain length at the same number of ethoxylated groups in the surfactants (NFAES). The surfactants (NFAES) have a perfect performance as corrosion inhibitors. The results revealed that C2 > C1 in the IE% at the same studied dose of each surfactant, The IE% reached 85% at the very low dose of 30 ppm. Potentiodynamic measurements (PP) revealed that the NFAES surfactants are working as mixed type of inhibitors for both cathodic (reduction) and anodic (oxidation) reactions. The critical micelle dose for C1 is 350 ppm while for C2 it is 30 ppm. IE% acquired from PP, electrochemical impedance spectroscopy, and electrochemical frequency modulation are approximatly the same. The surface morphology was analyzed and is discussed.

This study aimed to evaluate the effects of two different structural alcohol permeation enhancers (menthol and propylene glycol) on the internal structure and in vitro properties of the dual drug–loaded lyotropic liquid crystalline (LLC) gels. The LLC gels were prepared and characterized by polarized light microscopy, small-angle X-ray scattering, differential scanning calorimetry, attenuated total reflectance-Fourier transform infrared spectrum, and rheology. Based on the results, the inner structure of the gels was QII mesophase and exhibited a pseudoplastic fluid behavior. The level of internal order in the LLC mesophase would be affected by introduced 2 wt% menthol (MEN) and propylene glycol (PG). The in vitro release experiment showed that the release behavior of sinomenine hydrochloride (SH) and cinnamaldehyde (CA) from the LLC system was dominated by Fickian diffusion (n

In this study, biodegradable cardanol polyoxyethylene ether (CPE) was applied to the field of flotation deinking of mixed office waste paper (MOW), and its combination with fatty alcohol polyoxyethylene ether (AEO-9), fatty alcohol polyoxyethylene ether sulfate (AES) as a composite surfactant was also investigated for a green deinking process. The prepared composite surfactant was applied to the traditional alkaline chemical deinking. Moreover, the effect of cutinase on the deinking of MOW was also evaluated for the first time. Cutinases and amylases combined with the previously employed complicated surfactants were utilized to replace traditional chemicals for neutral deinking. The deinking effect and the environmental impact of these two deinking methods were evaluated in detail. The results showed that the surfactant composed of CPE/AEO-9/AES with a mass ratio of 1:1:1 can be used in traditional alkaline deinking, which could effectively improve the deinking pulp quality. Moreover, cutinase/amylase/surfactants deinking system could further enhance the deinking pulp quality. When pulped mixed office waste paper was treated with 0.2% of surfactants, 10 U g−1 of cutinase, 5 U g−1 of amylase at 50 °C for 30 min, the brightness of the deinked papers reached 92.24% ISO with an ink removal rate of 92.63%, tensile index of 24.83 N m g−1, and tear index of 9.48 mN m2 g−1. According to this study, cutinase and amylase combined with cardanol polyoxyethylene ether and other surfactants provide an environmentally friendly and effective deinking strategy.

Seeking to enhance coal mine safety, an experimental study of a kind of water-based explosion suppression medium for the absorption of mine gas was carried out. Using methane as the model gas, solubilizing experiments with different concentrations of anionic and nonionic surfactants were carried out using headspace gas chromatography for surfactants consisting of sodium fatty alcohol polyoxyethylene ether carboxylate (AEC), fatty acid methyl ester sulfonate (MES), fatty methyl ester ethoxylate (FMEE), hexyl d-glucoside (APG06), octyl beta-d-glucopyranoside (APG08) and n-decyl glucoside (APG10). By selecting individual surfactants, the study investigated the methane solubilization performance of water mist with binary anionic–nonionic surfactants. Furthermore, the release of methane in solution was also examined. The results show that the apparent solubility of methane in solution is linearly and positively correlated with the surfactant concentration. The methane solubilization is significantly improved by the addition of anionic–nonionic surfactants. The optimal solubilizing ratio of the anionic–nonionic surfactant varies with the solution compositions. For a fixed ratio, surfactant compositions exhibit the most distinct synergistic effect and the best performance for methane solubilization. The release of methane from mixed micelles composed of the compound solution is superior to that of a single surfactant. Through the analysis of the solubilization effect and the stability of different absorbents, it is concluded that the anionic–nonionic surfactant system shows much better capability than the other selected surfactants.

This work reports on the oxidation of long-chain aliphatic alcohols catalyzed by a stabilized alcohol dehydrogenase from S. cerevisiae (yeast alcohol dehydrogenase (YADH)). In particular, the oxidation of the fatty alcohol tetracosanol (C24H50O) to yield lignoceric acid (C23H47COOH) was studied. The immobilization of YADH onto glyoxyl agarose supports crosslinked with a polymer (polyethylenimine) produced a highly stable catalyst (60-fold higher than the soluble enzyme at 40 °C). Aliphatic alcohols with different chain lengths (ranging from 2 to 24 carbons) were studied as substrates for YADH. The activity of YADH with aliphatic alcohols with a chain length higher than five carbon atoms is reported for the first time. The activities obtained with the immobilized YADH were all similar in magnitude, even with long-chain fatty alcohols such as docosanol and tetracosanol. As far as the oxidation of tetracosanol is concerned, the best values of reaction rate and substrate conversion were obtained at pH = 8.2 and T = 58 °C. At these conditions, the soluble enzyme inactivated rapidly, precluding its use in batch reaction. However, using the immobilized YADH, up to three sequential reaction batches were performed by recovering the catalyst after each batch. Several applications in the green oleochemical industry, e.g., for making plasticizers, lubricants, detergents, and personal care products, may benefit from having novel and stable biocatalysts able to oxidize long-chain fatty alcohols.

This paper reports on a study that investigated the aquatic toxicity of new non-ionic surfactants derived from renewable raw materials, polyoxyethylene glycerol ester (PGE), and their binary mixtures with anionic and non-ionic surfactants. Toxicity of pure PGEs was determined using representative organisms from different trophic levels: luminescent bacteria (Vibrio fischeri), microalgae (Pseudokirchneriella subcapitata), and freshwater crustaceans (Daphnia magna). Relationships between toxicity and the structural parameters such as unit of ethylene oxide (EO) and hydrophilic-lipophilic balance (HLB) were evaluated. Critical micellar concentration (CMC) in the conditions of the toxicity test was also determined. It was found that the toxicity of the aqueous solutions of PGE decreased when the number of EO units in the molecule, HLB, and CMC increased. PGEs showed lower CMC in marine medium, and the toxicity to V. ficheri is lower when the CMC was higher. Given their non-polar nature, narcosis was expected to be the primary mode of toxic action of PGEs. For the mixture of surfactants, we observed that the mixtures with PGE that had the higher numbers of EO units were more toxic than the aqueous solutions of pure surfactants. Moreover, we found that concentration addition was the type of action more likely to occur for mixtures of PGE with lower numbers of EO units with non-ionic surfactants (alkylpolyglucoside and fatty alcohol ethoxylate), whereas for the mixture of PGE with lower EO units and anionic surfactant (ether carboxylic derivative), the most common response type was response addition. In case of mixtures involving amphoteric surfactants and PGEs with the higher numbers of EO units, no clear pattern with regard to the mixture toxicity response type could be observed.

The present work provides a systematic study to delineate the reaction mechanism and develop a mechanistic kinetic model for the hydrodeoxygenation (HDO) of triglycerides (TG) over alumina supported nickel catalyst. The HDO of 1:2 molar mixtures of tripalmitin and tristearin was studied in a batch reactor over a wide range of process conditions. The results showed that TG instantaneously converted to respective fatty acids. The fatty acids further converted to the fatty aldehydes. The fatty aldehydes, then, rapidly converted to alkanes by two parallel reaction pathways. The decarbonylation of fatty aldehyde (RP-I) was the dominating route compared to the reduction of the fatty aldehyde to fatty alcohol followed by its dehydration and hydrogenation (RP-II). A mechanistic kinetic model was developed based on the observed reaction pathway to correlate the experimental results. The rate constants for the conversion of palmitic acid and stearic acid to alkanes were matched closely with each other thereby demonstrating that HDO is independent of fatty acid chain length. The developed kinetic model was further validated using experimental data at various hydrogen-to-nitrogen mole ratios in the gas phase. Furthermore, the rate constants obtained for various catalyst loadings were correlated by a linear equation with zero intercept.

Alkyl polyglucosides (APGs), which were first commercialized in the 1990s, are mild, non-ionic surfactants comprising fatty alcohols and glucose derived from recyclable starch. APGs have good properties as cleaners, foaming agents, and emulsifiers, and they do not undergo hydrolysis at an alkaline pH. In addition to their advantages over traditional synthetic surfactants, APGs are low-irritant surfactants that are nontoxic and easily degradable in the environment. Thus, APGs are considered to be environmentally friendly surfactants. Starmerella bombicola glycosylates long-chain omega or omega-1 hydroxy fatty acids, and it also directly glycosylates secondary alcohols. Although it is generally difficult to directly glycosylate primary alcohols, they are easily converted to the corresponding fatty acids by S. bombicola because of its strong alcohol oxidase activity. To redirect unconventional substrates toward APG synthesis, the long-chain alcohol oxidation pathway was blocked by knocking out the fatty alcohol oxidase gene. The complete sequence of the S. bombicola FAO1 gene (2046 bp) was cloned, and the obtained nucleotide sequence was used to construct a knockout cassette. An FAO1 knockout mutant with the correct genotype and phenotype was evaluated by fermentation on 1-tetradecanol. The mutant produced tetradecyl disaccharides and tetradecanediol tetrasaccharides. The APGs and diol polyglucosides (DPGs) production of the mutant was 27.3 g/L ((APGs + DPGs)/de novo sophorolipids ratio was about 15:1), while the parent strain did not produce APG or DPG. These data indicate that the substrates had been redirected toward novel glycolipids synthesis in the mutant.

After the detection of the 1, 20, 21-C 29 long-chain triol in some sediments and freshwater pteridophytes, in this study, a new homologous long-chain triol, 1, 3, 4-C 27-29 , is detected for the first time in the Site4B core sediment in the northern South China Sea.The hydroxyl location and length of the carbon chain of this newly discovered triol differ from those of 1, 20, 21-C 29 triol.The test results of its molecular distribution and individual carbon isotope reveal that 1, 3, 4-C 29 triol has a good correlation with n -C 26-30 even carbon-numbered long-chain fatty alcohols, with R 2 ( n =68) values of 0.905, 0.929 and 0.903, respectively, and its carbon isotope composition, at -32.3‰±1.9‰, is similar to that of n -C 26-30 , at -29.13‰±0.87‰,-32.98‰±1.28‰, and -32.98‰±1.28‰.1, 3, 4-C 29 triol from the Site4B core sediment and terrigenous long-chain fatty alcohol( n -C 26-34 ) show highly consistent distribution trends in the entire section;thus, the former could serve as a proxy indicator of the terrigenous input. Considering that the 1, 20, 21-C 29 triol in previous research belongs to Azolla , which are fresh water pteridophytes, the 1, 3, 4-C 27-29 triol identified in this study might have similar biogenetic derivation.Thus, determination of its biogenic area and growing environment could provide potential organic geochemical evidence supporting the terrigenous input and source in the northern South China Sea.

The effects of surfactants on protease with and without stabilizer boric acid were investigated in this paper. From the structural features of surfactants, we discussed the possible mechanism between surfactants and protease. Surfactants studied were anionic surfactants having varying hydrophilic group and nonionic surfactants having varying hydrophobic types and chain length. The results showed that anionic surfactant linear alkyl benzene sulfonate (LAS) has the biggest influence on protease, due to benzene ring in its structure; nonionic surfactant fatty alcohol polyoxyethylene (AEO) with more ethylene oxide shows bigger impact on protease; carbon chain length in alkyl polyglucosides (APGs) has less influence on protease. Understanding the reaction mechanism of surfactants and protease is essential for many industry uses. Especially the results provide references for the application of protease in laundry formulation.

Microbial production of biodiesel from renewable feedstock has attracted intensive attention. Biodiesel is known to be produced from short-chain alcohols and fatty acyl-CoAs through the expression of wax ester synthase/fatty acyl-CoA: diacylglycerol acyltransferase that catalyzes the esterification of short-chain alcohols and fatty acyl-CoAs. Here, we engineered Escherichia coli to produce various fatty alcohol acetate esters, which depend on the expression of Saccharomyces cerevisiae alcohol acetyltransferase ATF1 that catalyzes the esterification of fatty alcohols and acetyl-CoA. The fatty acid biosynthetic pathways generate fatty acyl-ACPs, fatty acyl-CoAs, or fatty acids, which can be converted to fatty alcohols by fatty acyl-CoA reductase, fatty acyl-ACP reductase, or carboxylic acid reductase, respectively. This study showed the biosynthesis of biodiesel from three fatty acid biosynthetic pathway intermediates.

Background In vivo production of fatty acid-derived chemicals in Saccharomyces cerevisiae requires strategies to increase the intracellular supply of either acyl-CoA or free fatty acids (FFAs), since their cytosolic concentrations are quite low in a natural state for this organism. Deletion of the fatty acyl-CoA synthetase genes FAA1 and FAA4 is an effective and straightforward way to disable re-activation of fatty acids and drastically increase FFA levels. However, this strategy causes FFA over-accumulation and consequential release to the extracellular medium, which results in a significant loss of precursors that compromises the process yield. In the present study, we aimed for dynamic expression of the fatty acyl-CoA synthetase gene FAA1 to regulate FFA and acyl-CoA pools in order to improve fatty alcohol production yields. Results We analyzed the metabolite dynamics of a faa1Δ faa4Δ strain constitutively expressing a carboxylic acid reductase from Mycobacterium marinum (MmCAR) and an endogenous alcohol dehydrogenase (Adh5) for in vivo production of fatty alcohols from FFAs. We observed production of fatty acids and fatty alcohols with different rates leading to high levels of FFAs not being converted to the final product. To address the issue, we expressed the MmCAR + Adh5 pathway together with a fatty acyl-CoA reductase from Marinobacter aquaeolei to enable fatty alcohol production simultaneously from FFA and acyl-CoA, respectively. Then, we expressed FAA1 under the control of different promoters in order to balance FFA and acyl-CoA interconversion rates and to achieve optimal levels for conversion to fatty alcohols. Expressing FAA1 under control of the HXT1 promoter led to an increased accumulation of fatty alcohols per OD600 up to 41% while FFA levels were decreased by 63% compared with the control strain. Conclusions Fine-tuning and dynamic regulation of key metabolic steps can be used to improve cell factories when the rates of downstream reactions are limiting. This avoids loss of precursors to the extracellular medium or to competing reactions, hereby potentially improving the process yield. The study also provides knowledge of a key point of fatty acid regulation and homeostasis, which can be used for future design of cells factories for fatty acid-derived chemicals. Electronic supplementary material The online version of this article (doi:10.1186/s12934-017-0663-3) contains supplementary material, which is available to authorized users.

Electron trapping materials SrSO4:Eu2+ with various sizes and shapes were prepared by hydrothermal method with the assistance of fatty alcohol polyoxyethylene (3) ether (AEO-3) aqueous solution. Changing the molar ratios of [Sr2+]/[SO4 2−], the dendrites varied from needle, rod to octagonal and hexagonal disk architectures with sizes about 500 nm–4 μm width and 4–10 μm length. The growth mechanics of the particles was discussed to obtain a better understanding on their formation process. In the photoluminescence property investigations of SrSO4:Eu2+, the observed broadband was well identified with the electronic transition configurations of Eu2+. The thermal stability and electron trapping luminescence properties were also characterized.

Lipids are being increasingly used as biodiesel feedstock, and several saturated wax esters from Euglena gracilis are candidates for outdoor bulk production. Wax ester fermentation in Euglena is strongly increased by hypoxia, but key events underlying the metabolic shift toward wax ester biosynthesis are poorly understood. Profiling of wax esters and other lipophilic compounds is the first step for research toward the clarification of wax ester fermentation molecular mechanisms, and thus, a simple and comprehensive platform for their profiling is required. In this study, we established a profiling method for wax esters and lipophilic compounds in Euglena using gas chromatography-mass spectrometry (GC–MS). Using this method, we compared accumulation profiles of wax esters and lipophilic compounds between a wild-type Euglena Z strain and a bleached SM-ZK strain. Both the wild-type and the bleached strains contained C14:0 fatty acid-C14:0 fatty alcohol as a dominant wax ester. Wax ester fermentation initiated 4 h after the cessation of oxygen supply by halting the culture agitation resulting in linear increase and proportional changes of wax ester amounts during 24 h. However, complete anoxia by nitrogen gas aeration inhibited wax ester production and the addition of bicarbonates reversed the inhibition, suggesting that there is a need for an additional carbon source for wax ester fermentation under anoxia. Our simple method enables the investigation of metabolic responses leading to wax ester fermentation in Euglena.

The temperature gradient along the altitude transect of Mt. Jianfengling provides a good opportunity to establish and evaluate the microbial lipid-based environmental proxies. The soils collected from 14 different altitudes of Mt. Jianfengling contain abundant microbial fatty acids and fatty alcohols, including iso/anteiso fatty acids (i/aC12:0-i/aC19:0), 10-Me-C16:0 fatty acid, iso/anteiso fatty alcohols (i/aC13-iC26), 10-Me-C16:0 fatty alcohol and unsaturated fatty alcohols, which can indicate a strong microbial activity in the Jianfengling soils. The branched and unsaturated fatty alcohols can be only detected when saponification is performed, implying that these lipids are present as the constituents of bacterial wax esters in the soils. The ratio of aC15/iC15 fatty acids is positively correlated with altitude, suggesting that the decrease in temperature can induce the increase in the relative abundance of anteiso C15 fatty acid. In contrast, the ratio of aC15/iC15 fatty alcohols and of aC15/nC15 fatty alcohols both decrease with increased altitude or decreased temperature. Similarly, the ratio of nC18:1/nC18:0 fatty alcohols also decreases with decreased temperature, which is opposite to the previous observation that unsaturation of fatty acids in microorganism increases in response to decreased temperature. Besides, the average chain length (ACL) of long chain fatty alcohols (C22–C30) from leaf waxes and carbon preference index (CPI) of all n-fatty alcohols are also significantly correlated with altitude or mean annual temperature, demonstrating their potential for paleoclimate reconstruction. The correlation of microbial fatty acids and alcohols as well as ACL and CPI of plant wax-derived fatty alcohols with altitude may provide novel ways to reconstruct paleotemperature and paleoaltimetry.

The effect of trimethyl phosphate on Cu/Zn catalyst prepared by co-precipitation method for hydrogenation of methyl laurate to dodecanol in a slurry phase was studied using a stirred autoclave reactor system. The catalysts were characterized by means of XRD, EDS, XPS, SEM and BET. The results indicated that catalytic activity decreased with the increased amount of trimethyl phosphate. Correlating with the results from the above characterization, it was found that the main cause for the catalyst deactivation was the trimethyl phosphate occlusion of active sites by the physical adsorption and BET surface area decrement.

Although successful production of fatty alcohols in metabolically engineered Escherichia coli with heterologous expression of fatty acyl-CoA reductase has been reported, low biosynthetic efficiency is still a hurdle to be overcome. In this study, we examined the characteristics of two fatty acyl-CoA reductases encoded by Maqu_2220 and Maqu_2507 genes from Marinobacter aquaeolei VT8 on fatty alcohol production in E. coli. Fatty alcohols with diversified carbon chain length were obtained by co-expressing Maqu_2220 with different carbon chain length-specific acyl-ACP thioesterases. Both fatty acyl-CoA reductases displayed broad substrate specificities for C12-C18 fatty acyl chains in vivo. The optimized mutant strain of E. coli carrying the modified tesA gene and fadD gene from E. coli and Maqu_2220 gene from Marinobacter aquaeolei VT8 produced fatty alcohols at a remarkable level of 1.725 g/L under the fermentation condition.

Current biological pathways to produce biofuel intermediates amenable to separations and catalytic upgrading to hydrocarbon fuels are not cost effective. Previously, oleaginous yeasts have been investigated primarily for lipid production. However, yeasts store neutral lipids intracellularly making recovery difficult and expensive. In addition, once recovered from the cells, lipids are difficult to blend directly with the existing fuels without upgrading. We have, therefore, begun to investigate secreted fatty acid-derived products which can be easily recovered and upgraded to fuels. In this study, we successfully demonstrate the production of fatty alcohols by the oleaginous yeasts, Yarrowia lipolytica and Lipomyces starkeyi, through expression of the fatty acyl-CoA reductase gene from Marinobactor aquaeolei VT8. This strategy resulted in the production of 167 and 770 mg/L of fatty alcohols in shake flask from Y. lipolytica and L starkeyi, respectively. When using a dodecane overlay during fermentation, 92 and 99% of total fatty alcohols produced by Y. lipolytica and L. starkeyi, respectively, were extracted into the dodecane phase, which compares favorably to the 3 and 50% recovered, respectively, without the dodecane layer. In both oleaginous yeasts, long chain length, saturated fatty alcohols, i.e., hexadecanol (C16:0) and octadecanol (C18:0), were predominant and accounted for more than 85% of the total fatty alcohols produced. To the best of our knowledge, this is the first report of fatty alcohol production in L. starkeyi. This work demonstrates that the oleaginous yeasts, Y. lipolytica and L. starkeyi, can serve as platform organisms for the production of fatty acid-derived biofuels and bioproducts.

Background Fatty alcohols are important oleochemicals widely used in detergents, surfactants and personal care products. Bio-synthesized fatty alcohol provides a promising alternative to traditional fatty alcohol industry. Harnessing oleaginous microorganisms for fatty alcohol production may offer a new strategy to achieve a commercially viable yield that currently still seems to be a remote target. Results In this study, we introduced functional fatty acyl-CoA reductase (FAR), TaFAR1 to direct the conversion from fatty acyl-CoA to fatty alcohol in Yarrowia lipolytica (Y. lipolytica), an oleaginous non-conventional yeast showing great lipid-producing capability. Tri-module optimizations including eliminating fatty alcohol degradation pathway, enhancing TaFAR1 expression, and increasing fatty acyl-CoA supply were furtherly conducted, resulting in 63-fold increase in intracellular fatty alcohol-producing capability compared to the starting strain. Thus, this work demonstrated successful construction of first generation of Y. lipolytica fatty alcohol-producing cell factory. Through the study of effect of environmental nutrition on fatty alcohol production, up to 636.89 mg/L intracellular hexadecanol (high fatty alcohol-retaining capability) and 53.32 mg/L extracellular hexadecanol were produced by this cell factory through batch fermentation, which was comparable to the highest production of Saccharomyces cerevisiae under the similar condition. Conclusion This work preliminarily explored fatty alcohol-producing capability through mobilization of FAR and fatty acid metabolism, maximizing the intracellular fatty alcohol-producing capability, suggesting that Y. lipolytica cell factory potentially offers a promising platform for fatty alcohol production. Electronic supplementary material The online version of this article (doi:10.1186/s13068-016-0512-3) contains supplementary material, which is available to authorized users.

This paper presents a simple and convenient analytical method for determination of 1,4-dioxane in surfactants and detergents by using a novel SPME fiber. For the preparation of the fiber, the surface of a fused silica capillary tubing was modified by means of aluminium tri-tert-butoxide in a straightforward grafting process. The surface of our proposed fiber provides a Lewis acid–base interaction with analyte functional groups. The main factors affecting the extraction were optimized by using a central composite design method, which leads to the following optimum conditions: extraction temperature of 34 °C, extraction time of 4 min, equilibrium time of 13 min, and salt content of 25% (w/v). The optimum conditions showed a linear range from 0.005 to 60 μg g−1. LOD and LOQ of the proposed method were estimated to be 0.0015 and 0.005 μg g−1, respectively. This method was also applied for the analysis of some real samples including ethoxylated fatty alcohol, sodium lauryl ether sulfate, dish-washing agents, and shampoos by using the standard addition method.

Ecological and physiological studies focused on dietary preferences, lipid biochemistry and energetics within the three Antarctic chaetognaths Eukrohnia hamata, E. bathypelagica and E. bathyantarctica from meso- and bathypelagic depths. Eukrohnia hamata and E. bathypelagica respired 0.15 μL O2 mg dry mass (DM)−1 h−1, which translates to an average metabolic loss of only

Lactate esters are widely used as food additives, perfume materials, medicine additives, and personal care products. The objective of this work was to investigate the effect of a series of lactate esters as penetration enhancers on the in vitro skin permeation of four drugs with different physicochemical properties, including ibuprofen, salicylic acid, dexamethasone and 5-fluorouracil. The saturated donor solutions of the evaluated drugs in propylene glycol were used in order to keep a constant driving force with maximum thermodynamic activity. The permeability coefficient (K(p)), skin concentration of drugs (SC), and lag time (T), as well as the enhancement ratios for K(p) and SC were recorded. All results indicated that lactate esters can exert a significant influence on the transdermal delivery of the model drugs and there is a structure-activity relationship between the tested lactate esters and their enhancement effects. The results also suggested that the lactate esters with the chain length of fatty alcohol moieties of 10-12 are more effective enhancers. Furthermore, the enhancement effect of lactate esters increases with a decrease of the drug lipophilicity, which suggests that they may be more efficient at enhancing the penetration of hydrophilic drugs than lipophilic drugs. The influence of the concentration of lactate esters was evaluated and the optimal concentration is in the range of 5-10 wt.%. In sum, lactate esters as a penetration enhancer for some drugs are of interest for transdermal administration when the safety of penetration enhancers is a prime consideration.

The composition of lipids and fatty acids was determined for the livers, muscle, pancreas, kidney and stomach fluids of deepwater chondrichthyan species (including 11 squaliformes, 3 chimaeriformes, 1 hexanchiforme and 3 carcharhiniformes) caught as bycatch from continental waters off south-eastern Australia. The lipid class, fatty acid and fatty alcohol composition differed markedly in each tissue and in each species. The lipid and fatty acid composition of large, lipid-rich (38–70% wet weight, ww) livers demonstrated the multifunctional role of this organ in: lipid distribution, storage and biosynthesis, and buoyancy regulation. In the liver, the importance of certain lipids (including squalene, diacylglyceryl ethers, triacylglycerols and to a lesser extent wax esters) as mediators of buoyancy varied according to lifestyle and habitat. Less variability was observed in the muscle profiles, characterized by low lipid content ( 70%). The lipid and fatty acid profiles of the kidney and pancreas showed the highest intraspecific variability, suggesting these organs also have complex roles in lipid storage and metabolism. Overall intra- and interspecific differences in the tissue fatty acid profiles could be related to differences in a number of factors including phylogeny, habitat (depth), buoyancy regulation and diet and presumably also reflect different ecological roles. The lipid and fatty acid profiles are the first published for Rhinochimaera pacifica, Chimaera lignaria and Figaro boardmani and the first to demonstrate interspecific variation in lipid profiles of various tissues of deepwater chondrichthyans. The application of multivariate analysis to lipid class and fatty acid tissue profiles in chondrichthyans inferred dietary differences and metabolic preferences between species and habitats. These results have important implications for the future use of fatty acids as dietary tracers in chondrichthyan research.

The class of fatty alcohol alkoxylates describes surfactants that are synthesised by reaction of fatty alcohols with alkoxides such as ethylene oxide or propylene oxide or a combination of both as copolymers. Such alkoxylates are used, for example, as nonionic surfactants in home and industrial cleaning and washing agents. Chemical characteristics of such alkoxylate copolymers, for example the degree of alkoxylation, the arrangement of building blocks (random or block polymerisation), the type of the starter, and endcapping, play an important role in application behaviour. The analysis of these characteristics is challenging because in many cases such copolymers have high polydispersity and a large number of constitutional isomers depending on the degree of alkoxylation. Furthermore, the alkoxylates often occur in a complex multicomponent matrix. Here we present a method for characterization of silylated fatty alcohol alkoxylates in the low-molecular-weight range by means of comprehensive two-dimensional gas chromatography-mass spectrometry with electron impact and chemical ionisation. This method also enables detailed analysis of the alkoxylates in a complex matrix such as modern detergents.

The mechanism of deactivation of Cu/Zn catalyst poisoned by organic chlorides in hydrogenation of methyl laurate to lauryl alcohol in a slurry phase was studied in a stirred autoclave. The catalyst was prepared by co-precipitation, and the un-poisoned and poisoned catalysts were characterized using XRD, BET, ICP-AES and SEM, respectively. The results indicated that both of catalytic activity and selectivity decreased with increasing amount of chlorides in methyl laurate. According to the characterization of the catalysts, the main causes for the chlorine deactivation of the Cu/Zn catalyst were that the chlorides could modify the valence state of active sites, decrease the BET surface area, and promote the growth of crystal and catalyst agglomeration. Further investigation indicated that chlorine atom decomposed from the chlorides combined with ZnO to produce ZnCl2, which could be dissolved in the liquid and promote ester-exchange reaction to lauryl laurate as Lewis acid.

The effect of water on Cu/Zn catalyst prepared by co-precipitation for hydrogenation of methyl laurate in a slurry phase was studied using a stirred autoclave reactor system. The catalysts were characterized by means of XRD, BET, H2-TPR, SEM and TEM. The results indicate that catalytic activity decreases with increased amount of water in methyl laurate. Correlating with the results from the above characterization, it is found that the main causes for the water deactivation of the Cu/Zn catalyst were the water occlusion of active catalyst sites by the low solubility of water in the substrate and the promotion of crystal growth, as well as the Cu/Zn catalyst agglomeration in the presence of water.

Sulfated zirconia (SO4 2−/ZrO2) was proved as an efficient catalyst for the esterification of fatty acids and alcohols, the alkyl esters of long chain fatty acids are wildly used in industry and daily life. In this paper, the esterification of long chain fatty acid (both saturated and unsaturated) with simple alcohol catalyzed by SZ catalyst was presented. It is found that the degree of esterification reaction of the fatty acids with 1-butanol has a close relationship with the length and unsaturation degree of the chain. The longer the carbon chain is, the more difficult it is to react; the higher the unsaturation level is, the more difficult it is to respond. The related regulation will be confirmed and serve as the dictator for other reactions within this system.

In previous studies, Mucor circinelloides YR-1 isolated from petroleum-contaminated soils grown in decane as sole carbon source, showed fatty alcohol oxidase (FAO) activities in either particulate or soluble fractions from a cell-free extract. One is associated to internal membranes (mFAO) and the other one is soluble (sFAO). Both activities appear to be located in the cells in specific compartments other than peroxisomes. Results suggested that mFAO could be located on the inner face of the membrane of these compartments, and sFAO could be in the lumen of the specific compartments. This study reports on the intracellular distribution of FAO activity and the purification of sFAOs and mFAO after several different procedures for release from the membranous fraction using the mixed membrane fraction (MMF) after cellular homogenization as enzymatic source. Results with the purified mFAO show, by molecular weight criteria, that the enzyme has only one type of subunit with molecular mass of 46 kDa, with two isoelectric point components: 6.0 and 6.3. We found that mFAO is strongly associated to the MMF, possibly in a transitory fashion. Using non-denaturating gels, we suggest that sFAO and mFAO have the same subunits in their native structures, and, due to their native molecular weight of approximately 350 kDa, each could be natively structured as an octameric complex.

Zirconium sulfate (Zr(SO4)2 · 4H2O) was an efficient catalyst for the esterification of fatty acids and alcohols under solvent-free condition. The esterification of fatty acid with branched alcohols using Zr(SO4)2 · 4H2O catalyst gave a good yield of the corresponding ester. The zirconium sulfate Bronsted acid site was suggested to be the catalytically active species in this reaction. In addition, Zr(SO4)2 · 4H2O compound is a potential green catalyst due to its high catalytic activity and low toxicity. This compound is also cost effective, easy to handle, is easily recovered by simple filtration and can be recycled for further reactions.

The chemical constituents of a lipophilic extract from quince (Cydonia oblonga Mill.), obtained by supercritical fluid CO(2) extraction of the dried fruit pomace were investigated. Solvent partition of quince wax with n-hexane or acetone yielded an insoluble (crystalline) and a soluble (oily) fraction. Both fractions were analyzed separately using gas chromatography/mass spectrometry (GC/MS). The insoluble fraction consisted of saturated n-aldehydes, n-alcohols and free n-alkanoic acids of carbon chain lengths between 22 and 32, with carbon chain lengths of 26 and 28 dominating. Also odd-numbered unbranched hydrocarbons, mainly C27, C29 and C31, were detected particularly in the acetone-insoluble fraction (total, 15.8%). By means of vacuum liquid chromatography, triterpenoic acids were separated from the hexane-insoluble matter and identified as a mixture of ursolic, oleanolic and betulinic acids. The major constituents of the hexane-soluble fraction were glycerides of linoleic [Δ(9,12), 18:2] and oleic [Δ(9), 18:1] acids, accompanied by free linoleic, oleic and palmitic acids (C16). Moreover β-sitosterol, Δ(5)-avenasterol as well as trace amounts of other sterols were assigned. Finally the carotenoids phytoene and phytofluene were identified and quantified by UV/vis and high-performance liquid chromatography/MS techniques, yielding 1.0 and 0.3% of the quince wax, respectively. It is anticipated that the complex of lipid constituents from quince wax may exert interesting biological activities, the elucidation of which awaits further studies.

Lipids of the Arctic ctenophore Mertensia ovum, collected from Kongsfjorden (Svalbard) in 2001, were analysed to investigate seasonal variability and fate of dietary lipids. Total lipids, lipid classes and fatty acid and alcohol compositions were determined in animals, which were selected according to age-group and season. Changes in lipids of age-group 0 animals were followed during growth from spring to autumn. Total lipids increased from May to September. Lipids as percentage of dry mass were lowest in August indicating their use for reproduction. Higher values occurred in September, which may be due to lipid storage for overwintering. Wax esters were the major lipid class accounting for about 50% of total lipids in age-group 0 animals from July and August. Phospholipids were the second largest lipid fraction with up to 46% in this age-group. The principal fatty acids of M. ovum from all age-groups were 22:6(n-3), 20:5(n-3) and 16:0. Wax ester fatty alcohols were dominated by 22:1(n-11) and 20:1(n-9) followed by moderate proportions of 16:0. The unique feature of M. ovum lipids was the high amount of free fatty alcohols originating probably from the dietary wax esters. In May, free alcohols exhibited the highest mean proportion with 14.6% in age-group 0 animals. We present the first data describing a detailed free fatty alcohol composition in zooplankton. This composition was very different from the alcohol composition of M. ovum wax esters because of the predominance of the long-chain monounsaturated 22:1(n-11) alcohol accounting for almost 100% of total free alcohols in some samples. The detailed lipid composition clearly reflected feeding of M. ovum on the herbivorous calanoid species, Calanus glacialis and C. finmarchicus, the abundant members of the zooplankton community in Kongsfjorden. Other copepod species or prey items seem to be less important for M. ovum.

Static and dynamic contact angles of stock oil and its solutions with additives(fatty acid, fatty alcohol, fatty methyl ester usually used in rolling aluminum) were measured on aluminum surface (Alloy 1145) by sessile drop technique on an OCA35 dynamic contact angle tester. The effect of additive on the drop spreading was investigated as well. It is shown that the drop spreads very quickly in the first 500 ms after the lubricant contacts with the aluminum surface, and then does slowly later. The dynamic contact angle decreases exponentially with time. In contrast to the stock oil, although addition of polarity additive of long chain alkyl into stock oil is able to decrease the surface tension of solutions, it weakens the wetting dynamic, which results from the adsorption at the expanding solid/liquid interface. Among the same long chain polarity organic compounds used, dynamic wetting decreases in the order of fatty acid, fatty alcohol and fatty ester. The blend of fatty alcohol and fatty methyl ester can improve the oil wetting dynamics and promote the lubricant spreading.

By reductive glyceride cleavage food fats of different origin, converted to free glycerol and to fatty alcohols of the corresponding fatty acids, were investigated. Multielement IRMS-analysis (δ13C, δ18O) of the decomposition products was performed in order to develop GC-IRMS methods to the authenticity assessment of food fats. For this reason glycerol from olive oils of definite origin, as well as glycerol of commercially available edible fats and oils, was analysed. Furthermore, the determination of 18O/16O and 13C/12C isotope ratios of commercial glycerols from different origins was achieved. In addition, δ13CV‐PDB values of fatty alcohols corresponding to genuine fatty acid moieties were measured and their usability in view of fat authenticity assessment is discussed.

A new infrared spectroscopic method suitable for determining total fatty alcohol and fatty acid ester concentrations in industrial oils has been developed. Oil samples were diluted with toluene (1:3 w/w), the toxicity and volatility of which are relatively low compared with more commonly used IR solvents, like carbon tetrachloride or carbon disulfide. Mixture standards were prepared from dodecanol, tetradecanol, octadecanol, methyl stearate and methyl palmitate. Some analytical and statistical tests were performed on the developed method. The recoveries and the repeatability of the method proved to be sufficient for the quantitative determination of fatty alcohol and fatty acid ester additives in industrial oils. Reproducibility testing in another laboratory also produced satisfactory results. The developed method also proved to be relatively quick and simple. This method was developed to satisfy industry's need to determine the concentrations of these oil additives, and it has already been applied successfully in machinery oil analysis.

To better understand the trophic role of ctenophores in Antarctica during austral fall and winter, a major species of cydippid ctenophore, Callianira ant- arctica, was collected during April/May (fall) and August/September (winter) 2002 in the vicinity of Marguerite Bay. Lipid content, lipid classes, fatty acids, fatty alcohols and sterols were analyzed in animals, to- gether with lipid biomarkers in krill and copepod species representing potential ctenophore prey. Lipid content in ctenophores collected in winter was slightly higher than from animals in fall (4.8 and 3.5% of dry weight, respectively). Polar lipids were the dominant lipid class in ctenophores, accounting for over half of the lipid content, with significant amounts of free fatty alcohols (more than 10% of total lipid content) detected. Lipid- class composition, however, differed significantly be- tween seasons, with significant amounts of neutral lipid (wax esters and triacylglycerols) only detected in animals from fall. Although the dominant lipid classes in cte- nophores varied between fall and winter, individual lipids (i.e., fatty acids, alcohols and sterols) showed only minor changes between seasons. Specifically, long-chain polyunsaturated fatty acids (20:5(n-3) and 22:6(n-3)) found in high abundance in larval krill were also ele- vated in ctenophores collected in winter. Very high amounts of monounsaturated fatty alcohols, particu- larly 20:1(n-9) and 22:1(n-11), known to be important components of wax esters in calanoid copepods, were also observed. Multivariate analysis using the suite of lipids found indicated that copepods are an important diet item for ctenophores in the study area. Results further suggest that C. antarctica feed actively year- round, with larval krill providing a food resource during austral winter.

Highly sensitive chiral labeling reagents, (1R,2R)- and (1S,2S)-2-(2,3-anthracenedicarboximido)cyclohexanecarboxylic acids [(1R,2R)- and (1S,2S)-A] and (1R,2R)- and (1S,2S)-2-(2,3-naphthalenedicarboximido)cyclohexanecarboxylic acids [(1R,2R)- and (1S,2S)-A'], were prepared. Reagent A has enabled us to discriminate the enantiomers of anteiso fatty alcohols up to C9 methyl branching by 1H NMR, and both reagents A and A' have allowed up to C16 methyl branching at the 10(-15) molar level by fluorescence detected reversed-phase HPLC.

This work presents a method for the qualitative and quantitative analysis of non-ionic surfactant of the fatty alcohol ethoxylate and nonylphenyl ethoxylate types in lanolin. The lanolin dissolved in a mixture of methanol and methyl tert-butyl ether was analyzed with no time-consuming sample preparation. Coupling high-performance liquid-chromatography with electrospray ion trap mass-spectrometry gives an extracted ion chromatogram of every individual substance in the surfactant used. Sensitivity factors were determined as a function of fatty alcohol chain length and the degree of ethoxylation. The relationships found allow calculation of calibration curves for each single substance in the surfactant. In this way the content and distribution of each substance can be determined regardless of the surfactant contained in the sample. In contrast to calibration using reference surfactants or principal substances, even surfactants and surfactant mixtures with an unknown single substance distribution can be quantified. With this method of analysis the surfactants used for wool washing could be identified and quantified on the basis of reference samples. In addition, changes in the surfactant composition during the production of lanolin and its processing to Eucerit® could be followed.

The linear relationship between natural logarithm of width factor (lnp′)and natural logarithm of retention factor (lnk) is demonstrated. This relationship is then used to establish the relationship between (lnp′), absolute temperature (T), and carbon number (z), as follows: Inp′=A+bz+c/T+dz/T where A, b, c and d are thermodynamically related constants. The above equation is used to predict the unadjusted widths (w R ) ofn-alkanes, fatty alcohols and fatty acid methyl esters (FAMEs) at various temperatures, predicted values are in good agreement with experimental values. The above equation can be used to predict the width of FAMEs from rice bran oil. The largest difference between the experimental and predicted values is 0.66 s or 6.32%.

The kinetics of redox reactions of hemin adsorbed over a monolayer of long-chain aliphatic alcohols, such as cetyl alcohol (C16) and stearyl alcohol (C18), and stearic (C18), behenic (C22), and melissic (C30) acids is studied. The reaction inhibition on an alcohol monolayer (0.34 orders of magnitude per methylene group) is close to that reported in the literature. The inhibition on an acid monolayer is substantially smaller (0.2 to 0.07 orders), which is attributed to irregularity of the structure of the monolayer of carboxylic acids caused by the dissociation of carboxyl groups, especially in alkaline solutions. Violation of a regular structure of an acid monolayer is confirmed by a considerable irreversible increase in the electrode capacitance in alkaline solutions and by a decrease in the ohmic resistance of a monolayer of the longest saturated acid, i.e. triacontanoic acid. For a regular monolayer structure, when the length of an extended hydrocarbon chain defines the barrier thickness (alcohols), experimental data accord with predictions of the “superexchange” theory, which holds that the probability of a long-distance electron transfer depends on the length of the chain of covalent bonds over which the superexchange occurs. If the film structure is irregular (film thickness decreases with increasing hydrocarbon chain length (acids)), the packing of these bonds becomes essential, which allows the electron not to pass over all the bonds but to hop onto a nonbonded chain link nearby. The obtained data indicate that the electron transfer probability is defined by the electron's path, rather than by the barrier's geometrical thickness.

An enzymatic assay has been developed for the quantitative detection of alkyl polyglycosides after enzymatic hydrolysis with different carbohydrolases. A three-step enzymatic method was used for the quantification of alkyl polyglycosides. In the first step the enzymatic hydrolysis of alkyl polyglycosides was performed with different carbohydrolases, or an acid hydrolysis was used. The second step was quantification of free glucose with an enzyme electrode, which was covered with an immobilized glucose oxidase membrane; glucose was used as standard. The last step was the enzymatic quantification of fatty alcohols, which are the second substrate after enzymatic hydrolysis of alkyl polyglycosides. Surprisingly, the enzyme alcohol dehydrogenase ADH (E.C. 1.1.1.1) from bakers' yeast could efficiently oxidize a wide variety of aliphatic alcohols and had the highest catalytic specificity with short and medium fatty alcohol substrates, including octanol and decanol.

Chinese tall oil samples, obtained from pulp and papermaking factories in Qinzhou and Jiamusi of China, were first divided into acidic and neutral fractions by saponification, extraction, and distillation. The obtained neutral fractions were then analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) after silylation with bis-(trimethylsilyl) trifluoroacetamide. The results obtained show that 10 types of compound (monoterpenes, sesquiterpenes, diterpenes, triterpenes, resin alcohols, resin aldehydes, steroids, fatty alcohols, phenols, stilbenes) exist in the neutral fractions of Chinese raw tall oil. In the neutral fractions from Qinzhou, 55 components were identified, 35 of which were found for the first time in Chinese raw tall oil; 12 components were discovered for the first time in raw tall oil. In the neutral fraction from Jiamusi, 45 components were identified, 9 of which were discovered for the first time in Chinese raw tall oil.

Rheological and optical properties of cetyltrimethylammonium chloride (CTAC)/fatty alcohol (FA), behenyltrimethylammonium chloride (BTAC)/FA and CTAC/FA/hydroxyethyl cellulose (HEC) emulsions have been studied with particular emphases on the effects of FA content, the difference in the chain length of the hydrophobic groups between CTAC and BTAC, and the addition of a water soluble polymer, HEC. The effects of the FA content are to accelerate the structure development during the aging period and to increase the storage modulus, the yield stress, and the zero-shear-rate viscosity in the three emulsion systems investigated. At a low FA content of 2% w/w, lamellar and vesicular aggregates and isolated multilamellar vesicles can be observed in the CTAC/FA and BTAC/FA emulsions, respectively. At a high FA content of 6% w/w or with an excess of FA present, networklike structures and sunflower-like structures form, respectively, instead, inducing a higher entanglement storage modulus and a higher yield stress relative to those emulsions with a low FA content. The effect of adding HEC to the CTAC/FA emulsion is to reduce the entanglement storage modulus and the yield stress, consistent with the optical observation that the presence of the polymer disrupts the formations of lamella and vesicular aggregates and network structures.

Immobilized Pseudomonas fluorescens lipase enzyme was used to enrich the important polyunsaturated fatty acid (PUFA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from tuna oil. Hydrolysis, esterification, and transesterification reactions were studied in detail to find out the fractionation pattern of DHA and EPA during these processes due to preferential selectivity for or against these PUFA. Hydrolysis with P. fluorescens biotype I lipase with stoichiometric amount of water content gave more than 80% of DHA and EPA in the free fatty acid (FFA) form after around 60% of hydrolysis. After some preferential specificity during the early stages of hydrolysis, P. fluorescens lipase exhibits nonselective characteristics on extended hydrolysis. Esterification of FFA extracted from the completely hydrolyzed mixture of tuna oil was found to be better with long chain fatty alcohol like octanol which lead to good enrichment (44.5% for DHA and 11.3% for EPA) and yields of the PUFA in the FFA form. Transesterification (ethanolysis) with immobilized P. fluorescens lipase enzyme resulted in good enrichment and recovery of DHA and EPA in the glyceride mixture. After around 60% of ester synthesis, 74% of (DHA + EPA) enrichment was achieved with yields of more than 90% in the glyceride mixture.