Search

Validation of a framework for unsaturated soil behaviour has frequently resulted in disagreement with basic propositions. A primary reason for this disparity is considered to be attributable to the anisotropic properties of the soil specimens tested as a result of preparation using one-dimensional compaction. As part of the work presented, comparison is made between tests on samples of unsaturated kaolin prepared at identical specific volumes and specific water volumes using isotropic compression and one-dimensional compression. The suctions in the samples were reduced to predefined values by wetting under low isotropic loading in a triaxial cell. The samples were then taken through various stress paths to failure, defined as the critical state strength, while the suctions were held constant. Stress path tests were also performed on samples without reducing the suction to predefined values. In the latter, constant water mass tests, the suctions were allowed to vary and were measured using a psychrometer. The results of the tests at critical state are compared with the propositions of Wheeler and Sivakumar. The shear strengths of samples with isotropic previous history are shown to be significantly greater than those of samples with one-dimensional stress history when plotted against the mean net stress. The normal compression lines, critical state lines and yield characteristics are also shown to be significantly influenced by the previous stress history and are shown to be different for isotropically and one-dimensionally prepared samples. [ABSTRACT FROM AUTHOR]

Biodiesel is an alternative fuel consisting of alkyl esters of fatty acids from vegetable oils or animal fats. The properties of biodiesel depend on the type of vegetable oil used for the transesterification process. Cetane number is one of the most significant properties to specify the ignition quality of any fuel. The cetane number of biodiesel fuels is considerably influenced by their fatty acid methyl ester composition. The objective of this work is to investigate the influence of fatty acid methyl ester composition on cetane number of biodiesel fuels. In the present work, 15 various biodiesel fuels were prepared and their cetane number was measured experimentally. A wide literature review was made and the measured cetane numbers were compared with the reported values. The dependence of cetane number of biodiesel fuels on their fatty acid ester composition investigated. It was found from the investigation that the unsaturation percentage can significantly affect the cetane number. [ABSTRACT FROM AUTHOR]

Abstract: An analytical model for describing the propagation and attenuation of Rayleigh waves along the free surface of an elastic porous medium containing two immiscible, viscous, compressible fluids is developed in the present study based on the poroelastic equations formulated by Lo et al. [Lo WC, Sposito G, Majer E. Wave propagation through elastic porous media containing two immiscible fluids. Water Resour Res 2005;41:W02025]. The dispersion equation obtained is complex-valued due to viscous dissipation resulting from the relative motion of the solid to the pore fluids. As an excitation frequency is stipulated, the dispersion equation that is a cubic polynomial is numerically solved to determine the phase speed and attenuation coefficient of Rayleigh waves in Columbia fine sandy loam permeated by an air–water mixture. Our numerical results show that, corresponding to three dilatational waves, there is also the existence of three different modes of Rayleigh wave in an unsaturated porous medium, which are designated as the R1, R2, and R3 waves in descending order of phase speed, respectively. The phase speed of the R1 wave is non-dispersive (frequency-independent) in the frequency range we examined (10Hz–10kHz) and decreases as water saturation increases, whose magnitude ranges from 20% to 49% of that of the first dilatational wave with respect to water content. However, it is revealed numerically that the R2 and R3 waves are functions of excitation frequency. Given the same water saturation and excitation frequency, the phase speeds of the R2 and R3 waves are found to be approximately 90% of those of the second and third dilatational waves, respectively. The R1 wave has the lowest attenuation coefficient whereas the R3 wave attenuates highest. [Copyright &y& Elsevier]

Abstract: Meeting sustainable energy demand with minimum environmental impact is a major area of concern in the energy sector. Alternative fuels such as biodiesel, ethanol etc. have been quite promising for fulfilling both these aspects. While biodiesel reduces emissions of CO, life cycle CO2, SO x , volatile organic compounds (VOC) and particulate matter (PM) significantly, the propensity for the production of NO x is an important problem that requires extensive research. NO x emission from a direct-injection diesel engine is mainly due to formation of thermal NO that is described by Zeldovich mechanism. Thus, studying temperature profile during biodiesel combustion can provide useful insights to the formation and destruction of NO x . The main objective of this work is to investigate the effect of component methyl esters of biodiesel on open air flame temperature distribution and the effect of blending biodiesel with diesel and oxygenates (ethanol and methyl acetate) on open air flames. This objective was achieved by obtaining thermocouple measurements and thermal infrared imaging of local flame temperatures of wick-generated open air flames. A relationship between blend proportions and relative flame temperatures were obtained. In general, it was found that blending oxygenates such as ethanol and methyl acetate into petroleum diesel tended to increase the flame temperature in comparison with straight diesel fuel. The analyses of relative flame temperatures of different components of biodiesel were performed to evaluate the effect of unsaturation level and the hydrocarbon chain length on the flame temperature. It was found that the saturated methyl esters resulted in greater flame temperatures in comparison to unsaturated methyl esters. It was also revealed that shorter chained fatty acid methyl esters lead to higher flame temperatures as compared to its longer chained counterparts. [Copyright &y& Elsevier]

Stress acclimating plants respond to abiotic and biotic stress by remodeling membrane fluidity and by releasing α-linolenic (18:3) from membrane lipids. The modification of membrane fluidity is mediated by changes in unsaturated fatty acid levels, a function provided in part by the regulated activity of fatty acid desaturases. Adjustment of membrane fluidity maintains an environment suitable for the function of critical integral proteins during stress. α-Linolenic acid, released from membrane lipid by regulated lipase activity, is the precursor molecule for phyto-oxylipin biosynthesis. The modulation of chloroplast oleic acid (18:1) levels is central to the normal expression of defense responses to pathogens in Arabidopsis. Oleic (18:1) and linolenic (18:2) acid levels, in part, regulate development, seed colonization, and mycotoxin production by Aspergillus spp. [ABSTRACT FROM AUTHOR]

The structural importance of the acyl group in lysophosphatidylcholine (LPC) as substrate of purified bovine lysophospholipase D (lysoPLD) was investigated. Among LPCs with saturated acyl chains, the K m value decreased according to the length of the acyl chain (C12–C16) up to the palmitoyl group, while the V m value showed no remarkable change. But, the extension of the acyl size to C18, as observed with 1-stearoyl LPC ( K m, 8.5 mM), rather resulted in a remarkable increase in the K m value. Meanwhile, the introduction of one double bond in the C18 saturated acyl chain led to a remarkable reduction in the K m value, as observed with 1-oleoyl LPC ( K m, 0.48 mM). Furthermore, 1-linoleoyl LPC ( K m, 56 μM) with two double bonds exhibited a smaller K m value than 1-oleoyl LPC, suggesting that the unsaturation degree might be important in augmenting the binding affinity of LPCs. A similar phenomenon was also observed with 1-arachidonoly LPC ( K m, 79 μM) or 1-docosahexaenoyl LPC ( K m, 36 μM). Overall, the order of catalytic efficiency ( V m/ K m value) of those LPCs seemed to be affected by the K m value rather than the V m value, which differed by at most threefold among LPC derivatives. Next, the introduction of a hydroperoxide group into 1-linoleoyl-LPC or 1-arachidonoyl LPC led to a further reduction in K m values (1-hydroperoxylinoleoyl LPC, 26 μM; 1-hydroperoxyarachidonoyl LPC, 33 μM), accompanied by a further increase in the V m/ K m values. Additionally, phosphatidylcholines (PCs) with an oxidized acyl chain at sn-2 position were found to be efficient as 1-palmitoyl LPC as substrates of lysoPLD. Taken together, the catalytic efficiency of LPCs or oxidized PCs as substrates of lysoPLD seems to be determined by the property of the acyl chain, length of the acyl chain, unsaturation degree and oxidation status. [ABSTRACT FROM AUTHOR]

Abstract: The electronically unsaturated cluster complex Os3Pt2(CO)10(PBu t 3)2 (10) was obtained from the reaction of Os3(CO)10(NCMe)2 with Pt(PBu t 3)2. Three side products: PtOs3(CO)10(PBu t 2)CMe2CH2(μ-H) (13), Os3(CO)10(PBu t 3)2 (14) and Pt2Os3(CO)10(PBu t 3)(PBu t 2)CMe2CH2(μ-H) (15) were also obtained from this reaction. The three osmium atoms in 10 lie in the equatorial plane of a trigonal bipyramid. The platinum atoms occupy the apical positions. When heated, compound 10 was converted to 15 by metallation of one of the methyl groups of one of the PBu t 3 ligands at the platinum atom to which it is coordinated. The platinum atom then shifted to an edge of the Os3 triangle by cleaving one of its Pt–Os bonds. Compound 13 also contains a metallated PBu t 3 ligand attached to the platinum atom of the tetrahedral PtOs3 cluster. Compound 10 reacts with hydrogen at 0°C to yield the di- and tetra-hydrido compounds Os3Pt2(CO)10(PBu t 3)2(μ-H)2 (11) and Os3Pt2(CO)10(PBu t 3)2(μ-H)4 (12) with the hydrido ligands bridging Os–Pt and Os–Os bonds. With each addition of hydrogen, one of the platinum atoms in the cluster was shifted to an edge of the Os3triangle. When solutions of 12 at 25°C were purged with nitrogen, hydrogen was eliminated and the compounds 10 and 11 were regenerated. The electronic structures of 10 and 11 were also investigated by Fenske–Hall molecular orbital theory. When compound 10 was exposed to hydrogen for 2.5h, compound 12 was formed together with the new tetranuclear metal cluster complexes PtOs3(CO)10(PBu t 3)(μ-H)2 (16), PtOs3(CO)9(PBu t 3)(μ-H)4 (17) and PtOs3(CO)8(PBu t 3)2(μ-H)4 (18). Compounds 16–18 contain tetrahedrally shaped clusters of four metal atoms with bridging hydrido ligands. All new compounds were characterized structurally by single-crystal X-ray diffraction methods. [Copyright &y& Elsevier]

Abstract: A diverse and complex array of lipids plays a vital role in structuring and organizing cell membranes. However, the details of lipid requirements for global membrane organization are poorly understood. One obstacle to this understanding is the difficulty of accurately manipulating the lipid composition of commonly studied mammalian cells. In contrast, the lipid composition of cells of ectotherms changes with changes in environmental temperatures. Thus, comparison of lipid probe diffusion in cells from animals living at different temperatures, together with biochemical analysis, can be used toward understanding membrane organization. We used two dialkyindocarbocyanine iodide (DiI) probes, of differing chain length, to probe lipid organization in terms of their lateral diffusion in eggs of the sea urchin Strongylocentrotus purpuratus. The lateral diffusion of our probes changed in urchins developing in the year of an “El Niño” weather event, which raised the ocean temperature by several degrees, suggesting alterations in membrane domain composition and structure. Indeed the changes in lateral diffusion were correlated with lower levels of unsaturated fatty acids and cholesterol in animals of the “El Niño” year than in animals of the preceding or following years. We found similar trends comparing DiI diffusion in membranes of eggs from 15°C waters with those from 10°C. Our findings establish a new approach for manipulating and studying membrane organization. [Copyright &y& Elsevier]

Summary: A central issue in the successful application of acoustic wave method to detect subsurface hydrological properties is a better understanding of the influence of soil texture on the propagation and attenuation of acoustic wave as moisture content is varied, which was numerically investigated in the present study. Our earlier studies have demonstrated the existence of three different modes of acoustic wave in an elastic porous medium containing two immiscible, viscous, compressible fluids. Based on the dispersion equation obtained in the Lo–Sposito–Majer (LSM) model, the phase velocity and attenuation coefficient of the P1 and P2 waves which respectively propagate the fastest and second fastest were determined as a function of water saturation for 11 soil texture classes. The slowest wave (P3) was not characterized in this study since it does not travel far, due to very high attenuation. To provide a more general result, the calculated phase velocity and attenuation coefficient for different soil textures were normalized by those computed for sand. The normalization leads the resulting dimensionless parameters to be frequency independent throughout the whole range (up to 500Hz) with Darcy’s law remaining valid for the description of each fluid flow under wave excitation. The normalized phase velocity of the P1 wave was shown to have a substantially constant value at higher water saturations, but in the lower saturation range it first increases to reach a certain maximum value for different soil types and then decreases. The physical parameter controlling this phenomenon is the ratio of two effective non-wetting fluid storativity factors. Numerical results reveal that the normalized attenuation coefficient of the P1 wave is sensitive to soil texture and water saturation. Sand and loamy sand have the highest and second highest attenuation coefficients for the P1 wave, respectively. The magnitude of the normalized phase velocity of the P2 wave is found to be, with very few exceptions at nearly full saturations, linearly associated with the intrinsic permeability, while relating to the normalized attenuation coefficient of the P2 wave in an opposite manner. These results provide a quantitative clue for acoustic wave method to explore the physical properties in the shallow subsurface. [Copyright &y& Elsevier]

Abstract: Influence of unsaturation present at the surfactant head on the activity of interfacially located enzyme, lipase, and horseradish peroxidase (HRP) is investigated in cationic reverse micelles of a series of surfactants having unsaturated (allyl and pyridinium moieties) as well as analogous saturated (n-propyl and piperidinium moieties) polar head. Lipase activity increases with n-propyl (saturated) substitution as the increase in the headgroup area (A min) presumably provides greater space for the enzyme to attain flexible conformation and increases the local concentrations of enzyme and substrate at the interface. In contrast, activity of lipase decreases with increasing number of allyl (unsaturated) substitution though A min gradually increased. Similar trend in deactivation was observed when unsaturation is present in cyclic ring (pyridine) at the surfactant head in comparison to the saturated analogue, piperidine. Circular dichroism (CD) spectra of lipase in reverse micelles indicate that ellipticity in the far-UV region increases with increasing unsaturation. Thus, lipase probably loses its α-helix content and thereby its activity. Inhibition of biocatalyst with increasing unsaturation at the polar head of surfactant is also observed in case of HRP, an oxidoreductase enzyme. [Copyright &y& Elsevier]

Abstract: The use of vegetable oil macromonomers (VOMMs) as co-monomers in emulsion polymerization enables good film formation without the use of traditional coalescing solvents which constitute volatile organic compounds (VOCs). However, the allylic protons associated with the fatty acid double bonds can result in extensive chain transfer, reduced rates of polymerization, and potential gel content. Different vegetable oils were derivatized to yield their respective VOMMs which were subsequently polymerized into latexes with conventional (meth)acrylate monomers. The degree of ambient crosslinking was related to the extent of chain transfer for the various vegetable oils. The retention of VOMM unsaturation depended on reaction temperature, and the greatest variability between high and low temperatures was exhibited by the linseed oil macromonomer (the highest level of unsaturation). Lower reaction temperatures minimized the negative impact of the chain transfer reactions, yielding latexes with higher molecular weights and greater retention of allylic unsaturation. Core–shell polymers were characterized by bimodal particle size distribution indicating that the presence of VOMM-rich droplets contributed little to homogeneous VOMM distribution. Optimized single-stage polymerizations resulted in significant preservation of unsaturation, good film-forming qualities, rapid drying, and improved solvent resistance. The resulting latexes exhibited potential for use in higher performance application than conventional latexes. This study has demonstrated that drying oils can be incorporated into emulsions in limited quantities as effective reactive monomers for internal plasticization and auto-oxidative crosslinking after application. Broader ranges of incorporation require further study of VOMM reaction kinetics as a function of structure and improved process methods for macromonomer incorporation into emulsion polymers. [Copyright &y& Elsevier]

Abstract: The design motif in ferrocene-based architectures plays an important role to secure the targeted chemical, electronic, opto-electronic, redox properties. One of such architectures includes motifs bearing an unsaturated backbone attached to one or both the cyclopentadienyl ring. This review focuses on the synthesis and properties of these special classes of ferrocenes having olefinic, and acetylenic and cumulenic backbones. [Copyright &y& Elsevier]

Abstract: The myocardial phospholipid fatty acid (FA) composition (mol %) of 7 avian species was determined, in a body mass range from 150 g (Japanese quail, Coturnix coturnix japonica) to 19 kg (turkey, Meleagris gallopavo). Significant allometric increases were found for C16:1 n7 (allometric exponent: B =0.15), C18:1 n7 (B =0.08), C18:1 n9 (B =0.24), C20:1 n9 (B =0.22) and C20:3 n3 (B =0.12); moreover, total monounsaturates (B =0.20) and the sum of n9 FAs (B =0.24) was also positively related to body mass. The total n3 FAs (B =−0.36), and within them C22:5 n3 (B =−0.41) and C22:6 n3 (B =−0.60) showed allometric declines, such as total polyunsaturated fatty acids (PUFA; B =−0.01), unsaturation index (B =−0.03) and mean FA chain length (B =−0.003). Comparing our results with earlier published data on avian skeletal muscle and divergent mammalian tissues, the allometric scaling of the above membrane forming fatty acids seems to be part of a general relationship postulated as the theory “membranes as metabolic pacemakers”. In addition, the cardiac muscle malondialdehyde concentration was negatively related to body mass (B =−0.16), referring to a lower level of lipid peroxidation in larger birds, and vice versa, indicating a progressive myocardial lipid peroxidation in smaller-bodied species. [Copyright &y& Elsevier]

Abstract: To examine the effect of phospholipids on PON1 activities, purified PON1 was exposed to phospholipids prior to the determination of arylesterase and paraoxonase activities. Phosphatidylcholines with saturated acyl chains (C10–C16) showed a stimulation of both activities, chain length-dependent, with a greater stimulation of arylesterase activity, suggesting the implication of lipid bilayer in the stimulatory action. Such a preferable stimulation of arylesterase activity was more remarkable with phosphatidylcholines with polyunsaturated acyl chains or oxidized chains at sn-2 position, implying that the packing degree of acyl chain may be also important for the preferable stimulation of arylesterase activity. Separately, 1-palmitoyl-lysoPC also stimulated arylesterase activity preferably, indicating that the micellar formation of lipids around PON1 also contributes to the stimulatory action. Additionally, phosphatidylglycerols slightly enhanced arylesterase activity, but not paraoxonase activity. In contrast, phosphatidylserine and phosphatidic acid (≥0.1 mM) inhibited both activities Further, such a preferable stimulation of arylesterase activity by phosphatidylcholines was also reproduced with VLDL-bound PON1, although to a less extent. These data indicate that phosphatidylcholines with polyunsaturated acyl chains or oxidized chain, or lysophosphatidylcholine cause a preferable stimulation of arylesterase activity, thereby contributing to the decrease in the ratio of paraoxonase activity to arylesterase activity. [Copyright &y& Elsevier]

Abstract: Cultured gilthead sea bream (Sparus aurata L.) are exposed to a multifactorial disease termed “winter syndrome”, and low temperatures are the recurrent inducing factor. The effects of low temperatures on tissue composition and fatty acid profiles of polar and non-polar lipid fractions of sea bream were studied in two conditions: a gradual temperature drop (GD: from 18 °C to 8 °C at a rate of 1 °C·day−1) or two sharp drops (SD: from 18 °C to 12 °C and then from 12 °C to 8 °C completed within a day, with a 1 week interval). No significant differences were detected between GD and SD in any of the variables studied. Animals stopped feeding when the temperature fell below 13 °C, and the resulting fast provoked body weight losses of 12% (GD) and 10% (SD) at the end of the experiment (15th day), and decreased non-polar lipids content in muscle. Unsaturation of polar fatty acids in muscle (SD) and in gills (SD and GD) rose, demonstrating a homeoviscous acclimation of membranes to cold. In contrast, unsaturation of liver polar fatty acids did not rise, but liver showed a great increase in total lipid content on day 15 (+35% SD, and +43% GD), caused by the increase in non-polar lipids, especially n-3 fatty acids. The high deposition of these essential fatty acids, mainly 22:6n-3, in fasting sea bream implied mobilization from extra-hepatic stores and caused dramatic modifications in the physical properties of the liver (larger, more friable and yellowish), often associated with winter disease. Moreover, plasma aspartate aminotransferase (ASAT) levels rose three-fold in the two conditions. No fish succumbed to winter disease, but the incipient appearance of symptoms was evident. The relationships between the changes in muscle, gill, and, especially liver, at low temperature and the clinical signs of ‘winter disease’ are discussed. [Copyright &y& Elsevier]

Abstract: The effects of growth temperature and salinity on the cellular fatty acids were investigated on Aeromonas caviae, Aeromonas hydrophila and Aeromonas sobria. Under optimal growth conditions, fatty acids patterns were dominated by even-numbered chains C16:0, C16:1cis9, C18:1cis11, C12:0 and C14:0. Growth temperature modifications induced, in the three Aeromonas species, important changes in fatty acid (i) unsaturation, (ii) branching and (iii) chain length. An important decrease in the C18:1cis11 fatty acid content was observed for the three species below 15 °C and above 25 °C. The evolution of C18:1cis11 and C16:0 showed a mirror image for the three Aeromonas species. Low NaCl concentrations did not elicit significant changes in the fatty acids content of the three Aeromonas species. However, for high NaCl concentration in the medium, the growth ability was related to an important decrease of the unsaturated to saturated fatty acids ratio indicating a membrane rigidification. Thermal and salinity adaptations were branched fatty acid-dependent for A. caviae, whereas this phenomenon was less significant for A. hydrophila and A. sobria. [Copyright &y& Elsevier]

Abstract: Two random reduction procedures (NH2NH2/H2O2 and NH2NH2/O2) were compared and conditions optimized for the reduction of two synthetic pheromone compounds (9Z,11E)-9,11-tetradecadienyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate on a 300μg scale at 60°C. The relative amounts of the four products (completely reduced acetate, unreacted diene acetate and two monoene acetates), characterized by gas chromatography (GC) from the reaction mixture, depended on the reaction conditions. The reduction was straightforward without any detectable undesired side products. The reaction yields were reproducible with both the reducing reagents. The optimized reduction conditions thus established were utilized to reduce seven synthetic compounds (four diene and three triene acetates) on a micro scale (5μg). In all cases, expected compounds were identified by GC–MS. After reduction, two methods were used to locate the position of double bonds in the partially reduced compounds. In the first method, the products from the above seven compounds were isolated by extraction with hexane and reacted with dimethyl disulfide to give the DMDS adducts. In the second method (“one-pot”), the reduced compounds were not isolated but instead, the solvents were evaporated and the DMDS derivatives formed. In both cases, determination of the position of the double bonds was possible by GC–MS analyses. The complete procedure (reduction and DMDS derivative formation) could be carried out on a 100ng scale. Although neither of the partial reduction methods offered significant advantages over the other, partial reduction with NH2NH2/H2O2 was more convenient and hence should be the method of choice, together with DMDS derivative formation to locate double bonds in pheromones. In addition, a new procedure is described using ND2ND2/H2O2 and DMDS derivative formation capable of distinguishing between the double bond positions in (Z)-9-tetradecenyl acetate and (9Z,12E)-9,12-tetradecadienyl acetate (1:1 mixture). [Copyright &y& Elsevier]

Abstract: Sugar beet seedlings (Beta vulgaris L. cv. Monohill) were cultivated for 3 weeks at different root and shoot temperatures and the plasma membranes (PM) from roots were purified by aqueous two-phase partitioning and analyzed for lipid composition and ATPase activities. Lipid analyses, undertaken immediately after PM purification from the roots, showed that a low root zone temperature (10 °C) decreased the ratio between the major lipids phosphatidylcholine (PC) and phosphatidylethanolamine (PE). A low temperature in the root environment increased the mol% of PE and decreased the mol% of phosphatidic acid (PA), independent on the shoot growth temperature. A low temperature also decreased the mol% of linoleic acid (18:2) and increased mol% of linolenic acid (18:3) in the analyzed lipid classes, especially in PC and PE. The ratio between acyl chain lipids and protein generally increased in PM from roots grown at 10 °C, compared with higher temperature. The changes in lipid composition correlated with changes in ATPase activities, detected as hydrolyses of MgATP. The kinetic parameters, K m and V of the PM H+ATPase in roots increased at a low cultivation temperature, independent on shoot temperature. Moreover, Arrhenius analyses showed that the transition temperature was independent of both root or shoot growth temperature at 10–24 °C, whereas the activation energy of the ATPase was dependent on the growth temperature of the root, and independent on shoot temperature. Thus, acclimation processes can take place in roots, irrespective of the shoot temperature. [Copyright &y& Elsevier]

Abstract: Desaturation of fatty acids is a key reaction in the biosynthesis of moth sex pheromones. The main component of Spodoptera littoralis sex pheromone blend is produced by the action of Δ11 and Δ9 desaturases. In this article, we report on the cloning of four desaturase-like genes in this species: one from the fat body (Sls-FL1) and three (Sls-FL2, Sls-FL3 and Sls-FL4) from the pheromone gland. By means of a computational/phylogenetic method, as well as functional assays, the desaturase gene products have been characterized. The fat body gene expressed a Δ9 desaturase that produced (Z)-9-hexadecenoic and (Z)-9-octadecenoic acids in a (1:4.5) ratio, whereas the pheromone gland Sls-FL2 expressed a Δ9 desaturase that produced (Z)-9-hexadecenoic and (Z)-9-octadecenoic acids in a (1.5:1) ratio. Although both Δ9 desaturases produced (Z)-9-tetradecenoic acid from myristic acid, transformed yeast grown in the presence of a mixture of myristic and (E)-11-tetradecenoic acids produced (Z,E)-9,11-tetradecadienoic acid, but not (Z)-9-tetradecenoic acid. The Sls-FL3 gene expressed a protein that produced a mixture of (E)-11-tetradecenoic, (Z)-11-tetradecenoic, (Z)-11-hexadecenoic and (Z)-11-octadecenoic acids in a 5:4:60:31 ratio. Despite having all the characteristics of a desaturase gene, no function could be found for Sls-FL4. [Copyright &y& Elsevier]

A new kind of double metal cyanide (DMC) complex catalyst based on Zn3[Fe(CN)6]2 was synthesized and developed by reaction between aqueous solutions of zinc chloride and potassium hexacyanoferrate with complexing agents to form a precipitate of the DMC compound. For obtaining favorable catalyst activity, the organic complexing agents such as t-butanol and polyols are employed. The complexing agents are incorporated into the catalyst structure, and are required for active catalysts. Several kinds of polyether polyols are prepared by the Fe–Zn DMC catalyst. The structure and properties of polyether polyols are characterized by GPC, FT-IR, and 13C NMR. The results show that the polyether polyols catalyzed by these Fe–Zn DMC catalysts are of low unsaturation, high molecular weight, narrow molecular distribution compared with the polyether polyols catalyzed by traditional KOH catalysts. High resolution 13C NMR analytical results show that head–tail addition and random stereoirregular structure is dominant in polyether polyols microstructures which are catalyzed by these DMC catalysts. [Copyright &y& Elsevier]

Concrete technologists generally assume that under-water concrete structures are fully saturated with water. Powers was the first to show that cement paste, which has been stored under water for 220 days, is still unsaturated. Since then, a number of workers have confirmed Powers’ observation for cement and concrete using various techniques. However, no explanation of these observations is available. In this paper, the above observations have been explained on the basis of hydrodynamics of water flow through a porous medium. Propagation of the saturation front, within the structure, is proportional to the square roots of pore radius and elapsed time after contact with water. The relevant pore radius is related to the relative humidity within the structure by Kelvin’s law. This explanation predicts that a concrete structure with a water/cement ratio of about 0.6 or below will remain unsaturated for a very long time. The implications of this continued unsaturation on freeze-thaw durability; creep under compressive load and the depth of chloride ion penetration in concrete have been discussed. [Copyright &y& Elsevier]

Density functional calculations, using B3LPY/6-31G(d) methods, have been used to investigate the conformations and vibrational (Raman) spectra of a series of long-chain, saturated fatty acid methyl esters (FAMEs) with the formula CnH2nO2 (n=5–21) and two series of unsaturated FAMEs. The calculations showed that the lowest energy conformer within the saturated FAMEs is the simple (all-trans) structure and, in general, it was possible to reproduce experimental data using calculations on only the all-trans conformer. The only exception was C6H12O2, where a second low-lying conformer had to be included in order to correctly simulate the experimental Raman spectrum.The objective of the work was to provide theoretical justification for the methods that are commonly used to determine the properties of the fats and oils, such as chain length and degree of unsaturation, from experimental Raman data. Here it is shown that the calculations reproduce the trends and calibration curves that are found experimentally and also allow the reasons for the failure of what would appear to be rational measurements to be understood. This work shows that although the assumption that each FAME can simply be treated as a collection of functional groups can be justified in some cases, many of the vibrational modes are complex motions of large sections of the molecules and thus would not be expected to show simple linear trends with changes in structure, such as increasing chain length and/or unsaturation. Simple linear trends obtained from experimental data may thus arise from cancellation of opposing effects, rather than reflecting an underlying simplicity. [Copyright &y& Elsevier]

Abstract The present study investigated whether the cold-sensitive character of soybean is reflected at the level of mitochondrial membranes. When exposed to an increase of temperature (from 25 to 35 °C), mitochondrial membranes were characterized by a higher phosphatidylcholine : phosphatidylethanolamine ratio and a lower content in 18 : 3 fatty acid. After a reduction of temperature (from 25 to 18 °C) the opposite changes were found. Lipid lateral diffusion and local microviscosity appeared to be comparable in mitochondria from plantlets grown at 25 or 35 °C when assayed at the respective growth temperatures. Some functional aspects (cytochrome c oxidase activity or membrane conductance) tended to this behaviour whereas others (respiration rate or maximum membrane potential) did not. On the other hand, membranes from plants grown at 18 °C were more rigid. Moreover, as illustrated by cytochrome c oxidase activity or respiration rate, functional measurements suggested that these membranes were less active at this temperature. Thus the dynamic characteristics and functional properties measured in mitochondrial membranes were in favour of an adaptive trend at 35 °C, but not at 18 °C despite changes in lipid composition, in accordance with the cold-sensitive character of the plant. [ABSTRACT FROM AUTHOR]

This paper examines the constitutive behaviour of unsaturated mixtures of compacted sand-bentonite material. Two different techniques have been used to modify soil suction in laboratory specimens to examine the influence of suction on the behaviour of compacted materials. The two methods generated inherent differences in material fabric and therefore in stress-strain behaviour. The difference in microstructure generated by these two preparation techniques created different properties for the two series of specimens. This paper compares the behaviour of the two series of specimens and relates the observed mechanical behaviour to the initial soil fabric created by the two different preparation techniques. Specimens of similar compacted material were taken from two full-scale in-ground experiments conducted at Atomic Energy of Canada Limited's Underground Research Laboratory at Lac du Bonnet, Manitoba and sheared using the same triaxial equipment. The results are compared to the results of shearing laboratory compacted specimens. The research program demonstrates the need to understand the initial volume and suction states of plastic clays in order to predict the change in mechanical behaviour following a change in water content.Key words: constitutive relationships, unsaturation, laboratory tests, expansive soils, clays, shear strength.Cet article examine la loi de comportement de mélanges non saturés d'un matériau formé de sable-bentonite. Deux techniques différentes ont été utilisées pour modifier la succion du sol dans des spécimens en laboratoire afin d'examiner l'influence de la succion sur le comportement des matériaux compactés. Les deux méthodes ont généré des différences inhérentes dans la fabrique du matériau, et en conséquence, dans le comportement contrainte- déformation. La différence dans la microstructure générée par ces deux techniques de préparation ont créé de façon inhérente des propriétés différentes pour les deux séries de spécimens. Cet article compare le comportement des deux séries de spécimens et met en relation le comportement mécanique observé avec la fabrique initiale du sol créée par les deux différentes techniques de préparation. Des spécimens de matériaux compactés similaires ont été prélevés de deux expériences à grande échelle réalisées sur le terrain au laboratoire de recherche souterraine de l'AECL, et ont été cisaillés au moyen du même équipement triaxial. Les résultats sont comparés à ceux obtenus sur des spécimens compactés et cisaillés en laboratoire. Les résultats du programme de recherche démontrent le besoin de comprendre les états initiaux de volume et de contraintes dans les argiles plastiques pour prédire le changement dans le comportement mécanique à la suite d'un changement dans la teneur en eau.Mots clés : lois de comportement, non saturation, essais en laboratoire, sols gonflants, argiles, résistance au cisaillement.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Purpose. To compare the influence of the degree of fatty acid unsaturation (oleic [C18:1], linoleic [C18:2], or linolenic acid [C18:3]), with the intestinal lymphatic transport of halofantrine free base from disperse systems in anesthetized rats. Methods. The mesenteric lymph duct was cannulated in anesthetized rats. Lipid vehicle containing halofantrine was administered by intraduodenal infusion. The concentration of halofantrine in blood and lymph samples was analyzed. Results. The rank order of the lymphatic transport of halofantrine was C18:2 > C18:1 > C18:3. Comparison of the area under the curve (AUC) from the three fatty acids showed no statistically significant differences between the AUCs from the lymph cannulated rats. In terms of rank order effects, the plasma concentrations of halofantrine were highest for the rats dosed C18:2 followed by C18:3 and C18:1. Conclusions. Using C18:2 as a vehicle increased the lymphatic transport of halofantrine 16.6-fold over that observed for the system containing C18:3. The extent of lymphatic transport for the C18:1 system did not differ from the other two formulations, but the combined lymph and plasma data indicated that the C18:2 was the most suitable lipid vehicle for the oral delivery of halofantrine. [ABSTRACT FROM AUTHOR]

• A micromechanical framework is proposed for hydraulic transport properties of unsaturated CC. • The framework is a powerful tool for accurately predicting the hydraulic transport properties. • Spherical aggregates generate the maximal hydraulic transport properties compared to spheroidal ones. • Increasing ITZ thickness strengthens ITZ fraction and improves the hydraulic transport properties. Understanding of the coupled effects of aggregates and interfacial transition zones (ITZs) on hydraulic transport properties of unsaturated cementitious composites (CC) is of great importance for the design of CC durability. In this work, a comprehensive micromechanical theoretical framework is devised for the accurate predictions of the effective hydraulic conductivity, diffusivity and sorptivity of saturated and unsaturated CC, in which CC are regarded as a three-phase structure consisting of spheroidal aggregates with a certain gradation, their surrounding permeable ITZs with a specific thickness, and homogeneous cement paste at a mesoscopic level. Comparisons against experimental, numerical and analytical data suggest that the proposed framework is a reliable means to predict these effective hydraulic transport properties. The micromechanical framework can be regarded as a generic model that suits for predicting other hydraulic-like transport properties of multiphase composites not limited to cementitious composites involving spheroidal inhomogeneities and their surrounding interphase. This framework sheds light on the coupled effects of properties of aggregates (shape, gradation, mean size, and volume fraction) and ITZ (volume fraction, thickness, and hydraulic properties) on the effective hydraulic transport properties of CC. The results elucidate the complex relationship of components-structures-transport properties, which in turn can provide insights for understanding degradation of concrete in practical applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The styryl (Ph-CH=CH-R) group is widely represented in medicinally important compounds, including drugs, clinical candidates, and molecular probes as it positively impacts the lipophilicity, oral absorption, and biological activity. The analysis of matched molecular pairs (styryl vs. phenethyl, phenyl, methyl, H) for the biological activity indicates the superiority aspect of styryl compounds. However, the Michael acceptor site in the styryl group makes it amenable to the nucleophilic attack by biological nucleophiles and transformation to the toxic metabolites. One of the downsides of styryl compounds is isomerization that impacts the molecular conformation and directly affects biological activity. The impact of cis-trans isomerism and isosteric replacements on biological activity is exemplified. We also discuss the styryl group-bearing drugs, clinical candidates, and fluorescent probes. Overall, the present review reveals the utility of the styryl group in medicinal chemistry and drug discovery., (© 2022 Wiley-VCH GmbH.)

Gel-to-liquid crystalline transition temperatures (Tm) of phospholipids of five desiccation tolerant pollen species in vivo were compared at various levels of dehydration. In an attempt to explain chemically the differences in Tm between these species, phospholipids and soluble carbohydrate contents were examined. We observed a negative correlation between the number of double bonds per phosphohpid and Tm values for the intact pollen. This negative correlation also applied to Tm and the relative amount of linolenic acid. For the purpose of comparing Tm values of pollen and of unsaturated PCs (from the literature), the relative amounts and degree of unsaturation of pollen PCs were determined. A discrepancy between Tm values of individual PCs and intact pollen is discussed. Sucrose is the major soluble carbohydrate in 15 pollen species tested, generally making up a considerable pad of the dry weight. A positive correlation between sucrose content (either as a percentage of the dry weight or as grams sucrose per grams phospholipid) and Tm was established. This unexpected result was explained in terms of alternative adaptive strategies. We suggest that, for desiccation tolerance, pollen either has to contain sucrose for the protection of its phospholipids, or have a high degree of fatty acid unsaturation in its phospholipids. The advantages and disadvantages of the two options are discussed. [ABSTRACT FROM AUTHOR]

Free radicals, such as the superoxide anion, can damage the photosynthetic apparatus. At the same time they are increasingly formed as by-products of electron transport during stress conditions. For this reason, we studied the kinetics of formation and decay of superoxide anions in relation to changes, induced by increasing water deficit, in the composition of thylakoids. Seedlings of sunflower (Helianthus annuus L. cv. Licia Stella) were subjected to either a mild, a moderate, or a sever water deficit. Upon illumination of thylakoid membranes containing Tiron, we found first order kinetics of formation and decay of the Tiron semiquinone radical. At each stress intensity a higher rate of superoxide formation than in the control was observed. The different decay rates suggested a changed chemical environment around the radical. In comparison with the control, the levels of carotenoids and hydrophobic proteins in the thylakoids decreased, and the lipid/protein ratio increased after a mild water deficit. After moderate drought, the increased levels of hydrophilic proteins and carotenoids seem unsufficient to limit the improved capacity to leak electrons from the thylakoids. After a severe water stress, a decrease in unsaturation and in linoleic acid as well as a loss of lipolytic antioxidants took place, which may have rendered the thylakoids more sensitive to attack by activated forms of oxygen. The results suggest that during water deficit, the interactions among membrane components change in relation to a changed chemical composition. Such changes are probably among the causes for changes in the conformation of proteins and in the position of various molecular species in the lipid bilayer, so that they become more exposed to molecular oxygen. [ABSTRACT FROM AUTHOR]

Plants of garden pea (Pisum sativum L.) were exposed to charcoal‐filtered air with or without addition of 65 ± 5 l−1 ozone. Plants were harvested daily for 9 days and lipids were extracted from the second‐oldest leaf. Visible injury of this leaf was evident from day 5 on, while the differences in lipids between ozone and control treatments were observed earlier. Ozone caused large decreases in the contents of monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG) and sulfoquinovosyldiacylglycerol (SQDG), a slower decrease in the content of phosphatidylcholine (PC), but an increase in the content of phosphatidylethanolamine (PE) per leaf area, compared with exposure to charcoal‐filtered air. The content of phosphatidylglycerol (PG) was unaffected by ozone. Compared with charcoal‐filtered air, fumigation with ozone resulted in a decrease in the proportion of linolenic acid (18:3) of the total lipid extract, with a concomitant increase in the proportion of linoleic acid (18:2). For individual lipids, ozone caused a similar pattern of decreased 18:3 and increased 18:2 in MGDG, SQDG, PC and PE, while the fatty acid composition of DGDG was unaffected. In PG, ozone decreased the proportions of 18:3 and trans‐Δ3‐decenoic acid (16:1trans), balanced by increased proportions of palmitic and oleic acids. The contents of chlorophylls and carotenoids were unaffected by ozone. Our results show that moderately elevated levels of ozone cause significant changes in the polar lipid composition of garden pea leaves and in the level of unsaturation of the lipid acyl groups and, furthermore, that ozone has different effects, which could be direct or indirect, on chloroplast lipids (MGDG, DGDG, SQDG, PG acylated with 16:1trans) and cytosolic membrane lipids [ABSTRACT FROM AUTHOR]

The composition and positional distribution of fatty acids in the polar lipids from 4 strains of Chlorella differing in chilling susceptibility and frost hardiness were analyzed by enzymatic hydrolysis and gas‐liquid chromatography. Analysis of the polar lipids from chilling‐sensitive, chilling‐resistant and chilling‐sensitive revertant strains of Chlorella ellipsoidea IAM C‐102 showed that the sum of palmitic and trans‐3‐hexadecenoic acid in phosphatidylglycerol (PG) is about 60% for the sensitive strains and 53% for the resistant strain. The sum of dipalmitoyl and 1‐palmitoyl‐2‐(trans‐3‐hexadecenoyl) PG as estimated from the positional distribution of their fatty acids, is about 10% in the case of each of the three strains. The contents of unsaturated fatty acids in phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were higher in the resistant than in the sensitive strain. This suggests that unsaturation of fatty acids in not only PG but also PC and PE is involved in chilling sensitivity of Chlorella. On the other hand, lipid changes during the development of frost hardiness of C. ellipsoidea IAM C‐27, a frost hardy strain, were examined. The results showed that fatty acids in most lipid classes are unsaturated in the hardening process but their degree of unsaturation is not greatly different from that of the chilling‐resistant strain, suggesting that not only unsaturation of fatty acids in lipids but also other factors are necessary for the development of frost hardiness. [ABSTRACT FROM AUTHOR]

Sunflower seedlings (Helianthus annuus cv. Isabel) subjected to a moderate level of water stress showed a reduced growth and a 0.1 MPa osmotic adjustment came into play. Thylakoid membranes isolated from stressed leaves showed decreased chlorophyll (Chl) and protein contents but the Chl a/Chl b and protein/Chl ratios were unchanged. Water stress caused a preferential hydrolysis in thylakoid proteins: the hydrophilic to hydrophobic protein ratio increased from 0.8 in the control to 4.5 in the stressed plants. However, the degree of unsaturation was unchanged and the electron spin resonance (ESR) measurements did not show an increased level of O2·- radical production by photosynthetic membranes. [ABSTRACT FROM AUTHOR]

This paper proposes a model for determining the parameters given by the closed-form equations of van Genuchten. An objective function is made by the observed data from vertical drainage, and the solutions of optimization show that less computation and more accurate estimates are made as head profiles are taken into account rather than cumulative drainage. Sensitivity analysis of the error vector to parameters interprets this reason. The convergence and stability of solutions are evaluated with different magnitudes of measured errors in the head, and the results show good estimates will be obtained if a sufficient pressure head at the soil bottom is applied. A variable θ is introduced to avoid the estimations of α and n being affected by the uncertainties of Ks and θ. [ABSTRACT FROM AUTHOR]

Rhodotorula gracilis CFR-1 has been evaluated for its potential to produce lipids. The yeast lipids closely resembled palmolein, a liquid fraction of palm oil. It contained 2.3-3% free fatty acids, 64.4% tri-, 23.1% di-, and 6.1% mono-acylglycerols, 94.2% neutral and 5.8% polar lipids. Most abundant fatty acids were C18∶1, C16∶0, C18∶2 and C18∶0 (43.8, 28.5, 13.5 and 4.5%). All fatty acids, irrespective of the levels, followed definite patterns of increase or decrease during the advancement of fermentation. A pincers-shaped curve was obtained when the total saturation and unsaturation were plotted. Use of different glucose and molasses-based media did not show any significant overall effect on saturation (34.4-39.5%) and unsaturation (60.4-65.3%). Desaturation of fatty acids was found to be a metabolic function occurring in the process of cell maturation. [ABSTRACT FROM AUTHOR]

An improved Raman spectroscopic procedure for the determination of the total unsaturation in oils and fats using Fourier Transform Raman (FT-Raman) spectroscopy is described. An important advantage of FT-Raman for these samples is that the spectra are fluorescence-free unlike dispersive Raman which often uses visible excitation. Samples can be analyzed without any pre-treatment thus eliminating the need for dissolution in toxic solvents. The short acquisition time of FT-Raman and the ease of application allowed for a rapid sample turnover. [ABSTRACT FROM AUTHOR]

Argentation thin-layer chromatography was investigated as a method of obtaining detailed compositional information about milk fat. A modified argentation thin-layer chromatography procedure, developed to optimize the separation of the complex mixture of total milk fat triacylglycerols, provided nine different groups of triacylglycerols, based on both the degree of unsaturation and the total length of fatty acid groups. Fatty acid methyl ester (FAME) analysis was performed to determine the composition of each band. Separation on the basis of chainlength was most pronounced among the fully saturated triacylglycerol groups, as evidenced by the high level of C4:0 and C6:0 in bands 7 and 8, respectively. For the cis-monoenoic triacylglycerols, the separation of C4:0 and C6:0 was less distinct. The cis,cis dienes and other dienoic, trienoic, or tetraenoic species were principally observed in two bands of retention factor <0.08 on the chromatography plate. Minimal cross-contamination of bands was observed, with the exception of the lowest of the trisaturate bands, band 7, in which trans-monoenes were found to be present. Three samples from different points of the New Zealand dairy season were separated by argentation thin-layer chromatography, and their FAME distributions were measured. In addition to differences in the masses of band extracts from these samples, levels of C10:0 and C12:0 in all bands, and levels of monounsaturates in the dienoic and trienoic bands, were found to differ. These changes were generally consistent with a pattern of decreasing fat hardness over the November to March period of a typical dairy season. [ABSTRACT FROM AUTHOR]

The combination of attenuated total reflectance (ATR) and mid-infrared spectroscopy (MIRS) with statistical multidimensional techniques made it possible to extract relevant information from MIR spectra of lipid-rich food products. Wavenumber assignments for typical functional groups in fatty acids were made for standard fatty acids: Absorption bands around 1745 cm, 2853 cm, 2954 cm, 3005 cm, 966 cm, 3450 cm and 1640 cm are due to absorption of the carbonyl group, C−H stretch, =CH double bonds of lipids and O−H of lipids, respectively. In lipid-rich food products, some bands are modified. Water strongly absorbs in the region of 3600-3000 cm and at 1650 cm in butters and margarines, allowing one to rapidly differentiate the foods as function of their water content. Principal component analysis was used to emphasize the differences between spectra and to rapidly classify 27 commercial samples of oils, butters and margarines. As the MIR spectra contain information about carbonyl groups and double bonds, the foods were classified with ATR-MIR, in agreement with their degree of esterification and their degree of unsaturation as determined from gas-liquid chromatography analysis. However, it was difficult to differentiate the studied food products in terms of their average chainlength. [ABSTRACT FROM AUTHOR]

The retention of individual fatty soils, in both the presence and absence of clay soil, on repeatedly soiled, aged, and washed unfinished Dacron/cotton blend was studied by means of a double-label radioactive tracer analysis. Fatty soil retention was influenced by unsaturation, polarity and chain length, but the presence of clay soil was not a significant factor under the experimental conditions employed.Fabric yellowing was measured on samples soiled with clay and pairs of fatty soils and on appropriate controls. None of the organic soils caused observable yellowing in the absence of clay. While clay soil alone contributed significantly to residual yellowness, additional yellowing occurred on samples soiled with clay, oleic acid, and triolein. It was hy pothesized that the yellowing behavior observed when clay, oleic acid and triolein were present was due primarily to the embedding of pigmented particulate soil in a polymerized fatty film during the second clay soiling process. [ABSTRACT FROM PUBLISHER]

A double-label radioactive tracer analysis was developed to determine the comparative retention of representative sebum components on cotton fabric after repeated soiling and laundering and to determine whether the presence or absence of clay significantly affected the retention of the fats. Retention was related to chain length, polarity, unsatura tion, and presence of clay.The yellowness of cotton soiled with pairs of fats was measured in the presence and absence of clay. Clay contributed significantly to the yellow color. When fat alone was present, there was no significant increase in yellowing until after the fifth wash for oleic acid and triolein. An interaction between the fats and clay caused additional yellowing which was possibly due to greater uptake of clay by entrapment in a fatty matrix and/or to catalysis of oxidation reactions of unsaturated fats by metal ions present in kaolinite clay. ' [ABSTRACT FROM PUBLISHER]

• Reactivity of a Pt-O 2 complex with CO 2. • Pt-Carbene-Phosphine Unsaturated Complex. • Crystal structure of a peroxycarbonate complex of platinum. The reaction of Pt(COD) 2 with one equivalents of IBut and PBut 3 at room temperature yields the unsaturated platinum mixed N-heterocyclic carbene and phosphine complex Pt(IBut)(PBut 3), 1. Complex 1 reacts rapidly with O 2 and CO to form the dioxygen adduct Pt(IBut)(PBut 3)(η2-O 2), 2 and Pt 3 trimer cluster complex [Pt(IBut)(CO)] 3 , 3 , respectively. Complex 2 further reacts with CO 2 at room temperature to give the peroxycarbonate complex Pt(IBut)(PBut 3)[η2-OOC(O)O], 4 , and the first example characterized by single crystal X-ray diffraction. The reaction of complex 2 with acetone also resulted in the formation of the peroxoacetonate complex Pt(IBut)(PBut 3)[η2-OOC(CH 3) 2 O], 5. All the structures for the complexes 1 – 5 were characterized by X-ray crystallographic studies. [ABSTRACT FROM AUTHOR]