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A series of symmetrical (ABA) and non-symmetrical (AAB) triacylglycerol (TAG) isomers containing “A,” palmitic (P; 16:0) acid,
and “B,” either oleic (O; 9c-18:1), elaidic (E; 9t-18:1), linoleic (L; 9c,12c-18:2) or linolenic (Ln; 9c,12c,15c-18:3) fatty
acids were synthesized by esterification of the thermodynamically more-stable 1,3-di- or 1(3)-monoacylglycerols [1,3-DAG or
1(3)-MAG], respectively. 1,3-dipalmitoylglycerol (1,3P-DAG) was esterified with O, L or Ln acid to prepare the symmetrical
TAG isomers POP, PLP and PLnP, while the O- E-, L- and Ln-1(3)MAG precursors, synthesized or obtained commercially, were esterified
with P acid to prepare the non-symmetrical TAG isomers OPP, EPP, LPP and LnPP, respectively. The drop point(s), solid fat
content and melting point values of the synthesized TAG were determined. The 1,3-dipalmitoylglycerol (1,3P-DAG) and 1(3)P-MAG
precursors were prepared, in multi-gram quantities, by partial glycerolysis (glycerol/p-toluenesulfonic acid) of tripalmitin. After fractionation by silica gel chromatography, the 1(3)P-MAG and 1,3P-DAG isomers
(ca. 80% of total MAG or DAG) were purified (>98%) by crystallization from acetone [silver ion-HPLC was utilized to determine
the structural purities of the DAG (or MAG) precursors, and the synthesized TAG]. Esterification of the appropriate, thermodynamically
more-stable MAG or DAG precursors was found to be a very versatile method for synthesis (in 80–90% yields) of multi-gram (3–5 g)
quantities of symmetrical and non-symmetrical TAG isomers, in chemical and structural purities of >96 and 97–99%, respectively.
The 1- and 3- positions on the glycerol backbone of the MAG, DAG and TAG molecules are assumed to be equivalent. Mention of
trade names or commercial products in this (publication) is solely for the purpose of providing specific information and does
not imply recommendation or endorsement by the US Department of Agriculture. 相似文献
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Identification of Acylglycerols Containing Dihydroxy Fatty Acids in Castor Oil by Mass Spectrometry 总被引:1,自引:0,他引:1
Ricinoleate, a monohydroxy fatty acid, in castor oil has many industrial uses. Dihydroxy fatty acids can also be used in industry.
The C18 HPLC fractions of castor oil were analyzed by electrospray ionization mass spectrometry of lithium adducts to identify the
acylglycerols containing dihydroxy fatty acids and the dihydroxy fatty acids. Four diacylglycerols identified were diOH18:1-diOH18:1,
diOH18:2-OH18:1, diOH18:1-OH18:1 and diOH18:0-OH18:1. Eight triacylglycerols identified were diOH18:1-diOH18:1-diOH18:1, diOH18:1-diOH18:1-diOH18:0,
diOH18:2-diOH18:1-OH18:1, diOH18:1-diOH18:1-OH18:1, diOH18:1-diOH18:0-OH18:1, diOH18:2-OH18:1-OH18:1, diOH18:1-OH18:1-OH18:1
and diOH18:0-OH18:1-OH18:1. The locations of fatty acids on the glycerol backbone were not determined. The structures of these
three newly identified dihydroxy fatty acids were proposed as 11,12-dihydroxy-9-octadecenoic acid, 11,12-dihydroxy-9,13-octadecadienoic
acid and 11,12-dihydroxyoctadecanoic acid. These individual acylglycerols were at the levels of about 0.5% or less in castor
oil and can be isolated from castor oil or overproduced in a transgenic oil seed plant for future industrial uses. 相似文献
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Symmetrical and non-symmetrical triacylglycerols (TAG) containing oleic (O; 9c-18:1) and elaidic (E; 9t-18:1) acids were required
as part of a study relating the physical characteristics and functionality of trans-containing TAG with the mouth feel, taste characteristics and related characteristics desired by consumers in frying oils
and pastries. To replace the trans isomers in frying oils—a significant part of frying oils prepared by partial hydrogenation of vegetable oils—without loss
of the sensory properties desired by consumers, required the initiation of a study relating the structure of trans-containing TAG with such characteristics as melting range, drop points, and other crystalline properties. Elaidic acid was
esterified to trielaidin (EEE), and the EEE partially converted (glycerol/p-toluenesulfonic acid) to a mixture containing ca. 40% DAG (the 1,3- and 1,2-isomers). The DAG fraction was separated by silica
gel chromatography, the 1,3-dielaidylglycerol (1,3EE-DAG) isomer isolated (structural purity >99%) by crystallization from
acetone and esterified with oleic acid (O) to yield EOE. The 1(3)O-MAG was purchased commercially and esterified with E acid
to prepare OEE. Both syntheses yielded multi-gram quantities of EOE and EEO, in 80–85% yields, and with structural purities
>99%. Thus, by careful selection of the thermodynamically more-stable MAG or DAG precursors, the symmetrical EOE and non-symmetrical
EEO isomers could be readily synthesized, and their drop point and melting point values determined.
The 1- and 3- positions on the glycerol backbone of the MAG, DAG and TAG molecules are assumed to be equivalent. 相似文献
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Magdalena Zibka Katarzyna Matysiak Katarzyna Walczak Marcin Gajek Katarzyna Cholewa-Kowalska 《International journal of molecular sciences》2022,23(4)
The aim of the work was to obtain hybrid coatings containing silver, copper, and zinc nanoparticles on the TiAlV medical alloy via a sol–gel process. The developed layers were designed to bring about a bactericidal and fungicidal effect, as well as for protection against surgical scratches during the implantation of implants used in veterinary medicine. In this work, the authors focused on evaluating the microstructure (SEM + EDS); the structure (XRD, FTIR); and the surface properties, such as wettability, free surface energy, and roughness of layers with various concentrations of metallic nanoparticles (2 and 5 mol %). Our results confirmed that the sol–gel method enables the easy manufacturing of hybrid layers endowed with different porosity values as well as various shapes and sizes of metallic nanoparticles. A higher concentration of nanoparticles was observed on the surface containing 5 mol % of metallic salts. The highest degree of homogeneity was obtained for the layers containing silver nanoparticles. In addition, the silver nanoparticles were round and had the smallest dimensions, even below 20 nm. The FTIR and XRD structural studies confirmed the presence of an organosilicon matrix containing all three types of the metallic particles. We conclude that the higher concentration of nanoparticles influenced the alloy surface parameters. 相似文献
8.
Quaternary ammonium salts (otherwise known as “quats”) commonly form the foundation of formulations in the antimicrobial industry.
Many studies have been conducted on the biological activity of surfactants derived from fatty acids viz. lauric acid, myristic
acid, stearic acid and palmitic acid and palm fatty acid with polyamine, i.e. 1(2-hydroxyethylpiperazine). The present paper
investigates the synthesis and surface-active properties of esteramide quats derived from the esterification of the above-mentioned
fatty acids and 1(2-hydroxyethylpiperazine) followed by quaternization using dimethyl sulphate (DMS). These derivatives were
fully characterized by using Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance (NMR) spectroscopy, and
13C-NMR spectroscopy. In addition to the cationic content, surface tension, CMC (critical micelle concentration), fabric softening,
rewettability, emulsification and dispersing power were determined as their surface-active properties.
相似文献
Shilpi MishraEmail: |
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A method is proposed for producing fatty acid esters of thermomechanical pulp (TMP) using fatty acids of intermediate chain length (C6-C12). The end objective is to use a stream of fatty acids produced via refining tall oil from Alberta's pulping mills. Depending on the degree of modification, these treated materials can serve either as reinforcement or as copolymers in composite applications. The effect of reaction conditions—reaction time, reaction temperature, fatty acyl concentration, and fatty acid chain length—on the degree of substitution of the pulp samples was studied. The reaction conditions were applied for each fatty acyl chloride and the pulp samples were characterized using X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, force tensiometry, time-of-flight secondary ion mass spectroscopy, atomic force microscopy, and thermal gravimetric analysis. The degree of substitution (DS) plateaued after two hours at a concentration of 0.25 M of hexanoyl chloride. These conditions were used for the other systems studied. The esterification of the pulp samples was heterogeneous as evident from both the AFM and SIMS images, because of the presence of lignin on the surface. Nevertheless, based on adhesion forces measured using AFM, the surface of the modified pulp samples was less polar. This was also confirmed via contact angle measurements. Also, the changes in chemical functionality were studied using FTIR and XPS with the appearance of peaks characteristic of C?O (esters) and an increase in intensity of the alkyl shifts, respectively. Finally, it was found that esterification significantly improved the thermal properties of the pulp samples. 相似文献
10.
The formation of oxide semiconductor films of the (Mn,Co,Cu)3O4 type by radio frequency magnetron sputtering is presented. The conditions of deposition and subsequent heat treatment make it possible to obtain films with electrophysical characteristics close to those of the bulk ceramic materials used as a target for magnetron sputtering. Two variants of thermistor geometry were implemented. In the first case, the working layer of oxide semiconductor was deposited directly on the dielectric substrate (planar geometry), and in the second case on the layer with high electrical conductivity (Ni or Al) forming the inner electrode (layered geometry). The lower limit of the nominal resistance of the planar thermistor while maintaining high temperature nonlinearity is ~ 10 kΩ. The layered structure with the inner electrode makes it possible to reduce the lower limit of resistance up to ~ 50 Ω without losing the temperature nonlinearity of the thermistor. In addition, heat treatment above 450 °C or current self-heating with sufficient power output leads to the appearance of a pronounced voltage nonlinearity, which increases the thermal constant B of thermistors from 2400–3400 to 5000–5500 K. The fields of application of oxide-film structures for the correction of linear resistors and the implementation of integration approaches in the construction of linearized sensors are discussed. 相似文献
11.
Reaction Sintering and Properties of Silicon Oxynitride Densified by Hot Isostatic Pressing 总被引:4,自引:0,他引:4
Richard Larker 《Journal of the American Ceramic Society》1992,75(1):62-66
Silicon oxynitride ceramics were reaction sintered and fully densified by hot isostatic pressing in the temperature range 1700°C to 1950°C from an equimolar mixture of silicon nitride and silica powders without additives. Conversion to Si2 N2 O increases steeply from a level around 5% of the crystalline phases at 1700°C to 80% at 1800°C, and increases a few percent further at higher temperatures. α -Si3 N4 is the major residual crystalline phase below 1900°C. The hardness level for materials containing 85% Si2 N2 O is approximately 19 GPa, comparable with the hardness of Si3 N4 hot isostatically pressed with 2.5 wt% Y2 O3 , while the fracture toughness level is around 3.1 MPa. m1/2 , being approximately 0.8 MPa.m1/2 lower. The three-point bending strength increased with HIP temperature from approximately 300 to 500 MPa. 相似文献
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研究了反式-1,4-聚异戊二烯(TPI)结晶性对不同用量过氧化二异丙苯(DCP)硫化的TPI性能的影响。结果表明,拉伸前后TPI试样的XRD曲线上结晶峰有明显不同。TPI预拉伸冷冻试样的拉伸性能与冷冻前后原始试样的差异明显。随着DCP用量的增加,500mm/min和50mm/min拉伸速率下测得的拉伸强度之间的差异变得越来越小;同一压缩率时,试样的压缩强度不断降低。在tanδ-温度曲线上,随着交联密度的提高,TPI低温损耗峰的tanδ值不断增大,而其高温损耗峰的tanδ值呈下降趋势。 相似文献
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Low density polyethylene (LDPE)/maleic anhydride grafted polyolefin elastomer (POE-g-MA) with multiwall carbon nanotubes (MWCNTs) wrapped by fumed silicon dioxide (SiO2) were prepared by melt mixing. The results revealed that SiO2 improved the dispersion of MWCNTs on matrix. SiO2 and MWCNTs both had a heterogeneous nucleation effect on matrix and the crystallinity of composites increased with adding SiO2, MWCNTs and MWCNTs/SiO2. The addition of MWCNTs modified by SiO2 increased tensile strength and elongation at break of composites compared with composite with raw MWCNTs. MWCNTs had a strong absorption effect, leading to an obvious decrease in reflectance at 1060 nm of composites. 相似文献
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Svetlana R. Derkach Yuliya A. Kuchina Daria S. Kolotova Ludmila A. Petrova Vasily I. Volchenko Andrei Yu. Glukharev Vladimir A. Grokhovsky 《International journal of molecular sciences》2022,23(22)
Protein isolates were obtained from marine hydrobionts by the method of isoelectric precipitation with a preliminary stage of protein alkaline solubilisation. Northern blue whiting was chosen as the raw material. Various technological modes of the solubilisation stage were used: the temperature of the reaction mixture was 4 or 20 °C, and the duration was 4 or 16 h. The yield of the product was 44–45% with a high content of the main component (protein) equal to about 95%. It has been shown that a decrease in the temperature and duration of the alkaline solubilisation stage provides the production of protein isolates with good technological properties, a low solubility, high swelling and high emulsifying ability, necessary for its use in the production of functional food products, including therapeutic and prophylactic effects. These technological properties are explained by a change in the composition and structure of the protein, the change being an increase in the content of essential amino acids and the proportion of α-helices in the polypeptide chain. The main patterns obtained will be used to obtain protein isolates from marine molluscs. 相似文献
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Analysis was done of the statistical results obtained by following recommended AOCS Collaborative Study Procedure M-86 to
evaluate the performance of Official Method AOCS Ce 1i-07, which provides a gas–liquid chromatography (GLC) procedure for
the determination of the fatty acid composition of oils containing long chain polyunsaturated fatty acids (PUFAs). The method
obtains relative between-lab reproducibility (%RSDR) values on the order of 5% or less for most fatty acids that are present
above ~0.5% w/w; however, the reproducibility worsens dramatically for analytes below this threshold. Apparently, several
participating labs had problems identifying small peaks in the sample chromatograms. They also had problems correctly identifying
certain larger peaks that occurred in a congested area of the sample chromatograms, including the 9c-16:1, 9c-11c-22:1, and
6c,9c,12c,15c-16:4 fatty acids. Finally, several analytes with chain lengths between 16 and 18 and between 21 and 22 carbons
that were present at moderate concentrations had worse than expected reproducibilities due to severe overlap of these analytes’
peaks. A detailed inspection of the contributed data shows that the relatively poor between-lab reproducibility for analytes
in this region is due to differences in the labs’ chromatographic efficiencies and perhaps in their methods of quantifying
highly overlapped peaks. 相似文献
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采用化学氧化法制备了不同膨胀体积的膨胀石墨(EG),通过聚丙烯酸酯对不同膨胀体积的EG进行包覆改性,利用改性后的EG制备改性EG/聚酰胺66(PA66)复合材料,研究了不同膨胀体积的改性EG对复合材料力学性能和导热性能的影响。结果表明,EG经丙烯酸酯改性后,EG的表面粗糙度和活性基团明显增加;复合材料弹性模量和弯曲强度均随改性EG膨胀体积的增加而增加,与未膨胀石墨相比,分别提升了36.1%、25.8%;拉伸强度、断裂伸长率和热导率随膨胀体积的增加呈先增加后减小的趋势。拉伸强度在EG膨胀体积为40 mL/g时达到最大值,为75.6 MPa;热导率在膨胀体积为20 mL/g时最佳,为2.56 W/(m·k),与未膨胀石墨相比,拉伸强度和热导率分别提升了33.3%和30.1%。 相似文献
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Comparative Evaluation of Physical Properties of Edible Chitosan Films Prepared by Different Drying Methods 总被引:1,自引:0,他引:1
Edible films are alternative packaging, which have recently received much attention due mainly to environmental reasons. Edible films may be formed from edible biomaterials such as polysaccharides, proteins, or lipids. Among these biopolymers, chitosan is of interest because it has a good film-forming property and is biodegradable, biocompatible, and nontoxic. Several techniques have been used to prepare edible chitosan films with various degrees of success. However, it is always interesting to find an alternative technique to produce films of superior quality at shorter processing (drying) time. In this study, the influences of different drying methods and conditions on the drying kinetics and various properties of chitosan films were investigated. Drying at control conditions (ambient air drying and hot air drying at 40°C) as well as vacuum drying and low-pressure superheated steam drying (LPSSD) at an absolute pressure of 10 kPa were carried out at different drying temperatures (70, 80, and 90°C). The properties of chitosan films, in terms of color, tensile strength, percent elongation, water vapor permeability (WVP), glass transition temperature (Tg), and crystallinity, were also determined. Based on the results of both the drying behavior and film properties, LPSSD at 70°C was proposed as the most favorable conditions for drying chitosan films. 相似文献
19.
Pornpimon Mayachiew 《Drying Technology》2013,31(2):176-185
Edible films are alternative packaging, which have recently received much attention due mainly to environmental reasons. Edible films may be formed from edible biomaterials such as polysaccharides, proteins, or lipids. Among these biopolymers, chitosan is of interest because it has a good film-forming property and is biodegradable, biocompatible, and nontoxic. Several techniques have been used to prepare edible chitosan films with various degrees of success. However, it is always interesting to find an alternative technique to produce films of superior quality at shorter processing (drying) time. In this study, the influences of different drying methods and conditions on the drying kinetics and various properties of chitosan films were investigated. Drying at control conditions (ambient air drying and hot air drying at 40°C) as well as vacuum drying and low-pressure superheated steam drying (LPSSD) at an absolute pressure of 10 kPa were carried out at different drying temperatures (70, 80, and 90°C). The properties of chitosan films, in terms of color, tensile strength, percent elongation, water vapor permeability (WVP), glass transition temperature (T g ), and crystallinity, were also determined. Based on the results of both the drying behavior and film properties, LPSSD at 70°C was proposed as the most favorable conditions for drying chitosan films. 相似文献
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Juliana Bodoprost Helmut Rosemeyer 《International journal of molecular sciences》2007,8(11):1111-1124
A set of 13 fatty acids was transformed into their phenacyl esters by reaction with phenacyl bromide in acetonitrile using 18-crown-6 as phase-transfer catalyst. Conditions for the RP-18 HPL chromatographic separation of most of the esters has been worked out. Using this standard the fatty acid spectra from skin surface sebum lipids of 17 test persons was taken after microwave-assisted hydrolysis, neutralization and extraction with n-hexane. Quantitative evaluation of the chromatograms exhibits that oleic acid predominates in the sebum of all test persons. In the second part of the work the chromatographic mobility (RE values) of fatty acid phenacyl esters is correlated with calculated physico-chemical parameters of the corresponding acids. The best linear correlation was found between the RE and the logP values. This is helpful for the structural elucidation of un-identified fatty acids in a chromatogram. 相似文献