Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl- and 1,2-diacyl glycerophospholipids in Japanese oysterCrassostrea gigas (Thunberg)

Molecular species of 1-O-alk-1′-enyl-2-acyl-, 1-O-alkyl-2-acyl-, and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (EPL) andsn-glycero-3-phosphocholine (CPL) of Japanese oysterCrassostrea gigas were analyzed by selectedion monitoring gas chromatography/mass spectrometry using electron impact ionization. The characteristic fragment ions, [RCH=CH+56]⁺ due to the alkenyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkenylacylglycerols, [R+130]⁺ due to the alkyl residue in thesn-1 position and [RCO+74]⁺ due to the acyl residue in thesn-2 position of alkylacylglycerols, [RCO+74]⁺ due to the acyl residues in thesn-1 and/orsn-2 positions of diacylglycerols, and [M−57]⁺ being indicative of the corresponding molecular weight, were used for structural assignments. For alkenylacyl EPL and CPL, 19 and 16 molecular species were determined, respectively. Two molecular species, 18∶0alkenyl-22∶6n−3 and 18∶0-alkenyl-22∶2-non-methylene interrupted diene (NMID), amounted to 53.2% and 47.9%, respectively. The alkylacyl EPL and CPL consisted of 16 and 20 molecular species, respectively, and the prominent components were 18∶0alkyl-22∶2NMID, 20∶1alkyl-20∶1n−11 (27.4%) and 20∶1alkyl-20∶2NMID (16.3%) in the former, and 16∶0alkyl-20∶5n−3 (23.0%) and 16∶0alkyl-22∶6n−3 (21.6%) in the latter. For the diacyl EPL and CPL, 14 and 51 molecular species were determined, respectively. The major molecular species were 18∶0–20∶5n−3 (37.4%), 16∶0–20∶5n−3 (14.2%) and 18∶1n−7–22∶2NMID (13.2%) in the former, and 16∶0–20∶5n−3 (33.4%) and 16∶0–22∶6n−3 (22.3%) in the latter. It was found that there were significant differences in the molecular species between the alkylacyl and diacyl EPL and the alkylacyl and diacyl CPL; the number of molecular species was larger in CPL than in EPL, while the number of total carbons and double bonds of the major molecular species were larger in the EPL than in the CPL. Alkenylacyl EPL were similar to alkenylacyl CPL in molecular species composition.     

Synthesis and characterization of poly(ester ether siloxane)s

A series of novel thermoplastic elastomers based on ABA‐type triblock prepolymers, poly[(propylene oxide)–(dimethylsiloxane)–(propylene oxide)] (PPO‐PDMS‐PPO), as the soft segments, and poly(butylene terephthalate) (PBT), as the hard segments, was synthesized by catalyzed two‐step melt transesterification of dimethyl terephthalate (DMT) with 1,4‐butanediol (BD) and α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) (M?_n = 2930 g mol^?1). Several copolymers with a content of hard PBT segments between 40 and 60 mass% and a constant length of the soft PPO‐PDMS‐PPO segments were prepared. The siloxane‐containing triblock prepolymer with hydrophilic terminal PPO blocks was used to improve the compatibility between the polar comonomers, i.e. DMT and BD, and the non‐polar PDMS segments. The structure and composition of the copolymers were examined using ¹H NMR spectroscopy, while the effectiveness of the incorporation of α,ω‐dihydroxy‐(PPO‐PDMS‐PPO) prepolymer into the copolyester chains was controlled by chloroform extraction. The effect of the structure and composition of the copolymers on the transition temperatures (T_m and T_g) and the thermal and thermo‐oxidative degradation stability, as well as on the degree of crystallinity, and some rheological properties, were studied. Copyright © 2006 Society of Chemical Industry     

Intestinal absorption of ester and ether glycerophospholipids in guinea pig. Role of a phospholipase A2 from brush border membrane

In vivo intestinal perfusion was used to follow the absorption of three different choline glycerophospholipids (CGP) in guinea pig. These included 1-[³H]palmitoyl-2-acyl-sn-glycero-3-phosphocholine (diacyl-GPC), 1-[³H]-O-hexadecyl-2-acyl-sn-glycero-3-phosphocholine (alkylacyl-GPC) and 1,2-di-O-hexadecyl-sn-glycero-3-phospho-[³H]-choline (dialkyl-GPC). About 80% of diacyl-GPC was absorbed within 4 hr, compared to 60% of alkylacyl-GPC and 30% of dialkyl-GPC. The radioactivity disappearing from the perfusion fluid was recovered in intestinal lipids, mostly triacylglycerol, free fatty acid and CGP from diacyl-GPC, CGP from alkylacyl-GPC and dialkyl-GPC. These results indicated that the nonhydrolyzable substrate dialkyl-GPC was much less absorbed, whereas diacyl-GPC, which released over 80% of [³H]palmitic acid in the perfusion fluid, displayed the highest absorption rate. The intermediate picture observed for alkylacyl-GPC suggested the possible involvement of a phospholipase A₂, which was detected in the entire intestinal tract. This enzyme was further found to concentrate in villus cells, where it is localized in the brush border membrane, as shown using two different subcellular fractionation procedures. These data suggest a possible role of this new enzyme in the digestion of alimentary phospholipids.     

Heat stabilization of segmented copoly(ether ester)s

Oxidative degradation of segmented copoly(ether ester)s can be suppressed by interference of the following basic processes: a. degradative radical chain reactions. Effective inhibition is possible by means of primary antioxidants. b. initiation of the radical chain reactions by means of hydroperoxides formed. Such initiation reactions can be suppressed by inactivation of the hydroperoxides with the aid of secondary antioxidants. c. polyester segmental chain scission by formic acid formed during oxidative degradation of the polyether segments. By scavenging the formic acid, or its precursor formaldehyde, this serious process can be restricted. Combined addition of stabilizers, simultaneously influencing the basic processes a., b. and c. can lead to synergism. Examples of the activity of the different stabilizers are given.     

Fatty acid composition of brain glycerophospholipids in peroxisomal disorders

This paper shows for the first time the differential fatty acid composition of ethanolamine plasmalogens (EP) and phosphatidylethanolamine (PE) in the brains of 12 patients with disorders of peroxisomal biogenesis and compares the results to normal values for the age. Other important glycerophospholipids (GPL), such as phosphatidylserine (PS) and phosphatidylcholine (PC), are also included in this study. GPL were separated by two-dimensional thin-layer chromatography, and their fatty acid composition was determined by capillary column gas-liquid chromatography. Total brain GPL were slightly decreased in peroxisomal disorders (27.98±2.95 μmol/g in the patients against 34.5±6.21 μmol/g in age-matched controls, P=0.005), and the distribution of the different GPL classes was much altered. In confirmation of known data, EP were very much decreased (2.18±1.3 μmol/g in the patients against 6.9±2.3 μmol/g in controls) at the expense of PE, which was increased (8.58±2.17 μmol/g in the patients against 5.97±0.58 μmol/g in controls, P<0.005). PS and PC were both significantly decreased (P=0.0001 and P=0.037, respectively). The polyunsaturated fatty acid (PUFA) composition of all the GPL fractions was markedly abnormal. In absolute terms, docosahexaenoic acid (22∶6n−3) was drastically decreased in all GPL classes (always at the P<0.0001 level) while arachidonic acid (20∶4n−6) was increased in PE and PS (P<0.001 in both cases). In the alkenyl acyl form, EP, 22∶6n−3, and 20∶4n−6 were both very significantly decreased (P<0.0001), although the former was always the most affected. The myelin PUFA adrenic acid (22∶4n−6) was decreased in EP (P<0.0001) and slightly increased in PS (P<0.05). The changes found confirm that 22∶6n−3 deficiency is a predominant defect in the brain in peroxisomal disorders.     

含锌聚醚酯酰胺的热性能研究

以氧化锌、脂肪族二羧酸、聚乙二醇为原料合成含锌聚醚酯(PEEM),再将PEEM与聚己内酰胺低聚合物反应,制备含锌聚醚酯酰胺(PEEAM),借助差示扫描量热法(DSC)、热重(TG)分析,研究了PEEAM的热性能。结果表明:PEEAM呈双熔融和双结晶峰,随PEEM含量增加,PEEAM中PEEM链段的熔融温度降低,熔融热焓增大,聚酰胺链段的熔融温度略有下降,结晶放热和结晶温度随PEEM含量变化有最小值;PEEAM中含脂肪族二羧酸种类不同,其相应的熔融温度、熔融热焓、结晶温度及结晶放热不同,没有明显规律可循。脂肪族二羧酸种类对PEEAM的初始降解温度和最大质量损失温度没有明显影响。PEEM含量增大,PEEAM的热失重速率增大。     

Influencing the crystallization behavior of PET-based segmented copoly(ether ester)

Segmented copoly(ether ester) based on poly(ethylene terephthalate) and poly(oxytetramethylene) suffers from having a rather low rate of crystallization. The crystallization behavior of this elastomer can be influenced by cocondensation of selected diols and addition of nucleating agents and plasticizers. Changes of the crystallinity and morphology are studied by differential scanning calorimetry and dynamic-mechanical analysis, respectively. Mechanical properties in relation to the different crystallinites obtained are reported.     

聚醚酯弹性纤维的改性研究

和丙三醇(GL),制备了改性聚醚酯弹性体,经熔融纺丝得到聚醚酯弹性纤维,讨论了TiO_2和GL对弹性纤维性能的影响。结果表明:0.4%～0.8%mol GL的加入和0.5%(w)TiO_2的加入都能提高聚醚酯弹性纤维的弹性回复率。GL的加入还使拉伸断裂强度和模量增加。与未改性聚醚酯弹性纤维相比,两种改性弹性纤维的声速和声速模量随拉伸倍数的增加而幅度下降。     

Copolymers of poly(2,6-dimethyl-1,4-phenylene ether) and ester units

Copolymers of telechelic poly(2,6-dimethyl-1,4-phenylene ether) segments with terephthalic methyl ester endgroups (PPE-2T, 3700 g/mol) and different diols were made via a polycondensation reaction. The terephthalic endgroups of PPE-2T are stable during this reaction. The T_g of these polyether-ester copolymers decreases with increasing diol length and diol flexibility. The T_g can be set between 100 and 200 °C by changing the type of diol. However at increasing diol length the T_g becomes broader and the test bars are less transparent because the extent of phase separation increases with increasing diol length. Only polymers with a diol length up to C12 are homogeneous. Phase separation is probably enhanced by the bimodal molecular weight distribution of PPE-2T. Phase separation can be suppressed by using shorter PPE-2T segments with a short diol. It is even better to use fractionated, monomodal PPE-2T. Copolymerisation is much more effective in decreasing the T_g of PPE and therefore its processability than blending with polystyrene. It is expected that the processability of these copolymers is much better than that of PPE.     

新型聚三唑酯和聚三唑醚树脂的合成及性能

合成了三种含酯基和三种含醚键的炔单体,通过核磁共振氢谱(¹H NMR)、红外光谱(FT-IR)、质谱(MS)、液相色谱(LC)对其结构进行了表征。用这六种炔单体与叠氮单体反应制备了一系列新型聚三唑酯树脂(PTAE)和聚三唑醚树脂(PTAO)。利用差示扫描量热分析(DSC)、FT-IR、动态力学热分析(DMA)、力学试验机和热失重分析(TGA)表征了树脂的固化行为、固化树脂的力学性能、耐热性和热稳定性。结果表明PTAE和PTAO树脂易溶于有机溶剂,可低温(60℃)固化,固化树脂的弯曲强度超过了100 MPa,可达158 MPa,玻璃化转变温度(T _g)超过180℃,高者达251℃,热分解温度可达360℃。     

Synthesis and characterization of poly(arylene ether) containing cyanate ester networks

A series of bisphenols containing ether linkage were prepared from halo phenol/dihalo compound and dihydroxy compounds in the presence of K₂CO₃. The bisphenols were transformed to cyanate esters by treatment with cyanogen bromide using triethyl amine catalyst. The structure of all the five bisphenols and the cyanate esters were structurally confirmed by FT-IR, ¹H-NMR and ¹³C-NMR spectral methods and elemental analysis. The cyanate esters were cured at 100 °C (30 min) → 150 °C (30 min) → 200 °C (60 min) → 250 °C (3 hr). The thermal properties of the cured resins were studied by DSC and TGA. DSC analysis shows that these cyanate esters exhibit T _g in the range of 203–234 °C. The CE(c) has the highest glass transition temperature. The cyanate ester CE(e) shows the lowest T _g which is due to its asymmetric structure. The initial degradation temperature of the cured resins was found to be in the range of 324–336 °C. The Limiting Oxygen Index (LOI) value, determined by Van Krevelen’s equation, is in the range of 35.5–38.7.     

聚丙烯/聚醚酯酰胺共混纤维的研制

用聚乙二醇与己二酸反应合成聚醚酯,再用聚醚酯与己内酰胺反应得到聚醚酯酰胺。将聚醚酯酰胺与聚丙烯共混并纺丝得到聚丙烯/聚醚酯酰胺共混纤维;研究了聚醚酯与聚醚酯酰胺的结构和热性质;考察了共混纤维性能。结果表明:聚醚酯含量增加,聚醚酯酰胺的熔点下降,结晶温度升高;共混纤维的抗静电性和回潮率随聚醚酯酰胺含量和聚醚酯含量的增加而增强;共混纤维有很好的可染性,但强度略低。     

Macromolecular assemblies of segmented poly(ester urethane)s and poly(ether urethane)s

Polyurethanes containing different soft and hard segments were investigated by fluorescence and scanning electron microscopy. The polarity dependence of the vibrational structure of the pyrene emission spectrum indicated the formation of aggregates at concentrations, which are significantly below the critical concentrations, which define the separation of dilute‐semidilute domains. Unlike the samples with 4,4′‐methylene diphenylene diisocyanate, the samples with 2,4‐tolylene diisocyanate in hard segments give the fluorescence spectra in which the pyrene excimer appears. The supermolecular structures associated with the form of spherulites or of spherical micelles were detected by scanning electron microscopy. The results were compared with previous reports concerning viscometric data. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Hydrolytic resistance of model poly(ether urethane ureas) and poly(ester urethane ureas)

Poly(ester urethane ureas) (PesURUs) and poly(ether urethane ureas) (PetURUs) synthesized from diphenylmethane-4,4′-diisocyanate and poly(butylene adipate) diol, and poly(tetramethylene oxide) diol or poly(propylene oxide) diol, respectively, were hydrolyzed at 70°C for various periods up to 16 weeks. Differences in thermal and mechanical properties of as-received dry samples are correlated with the number and strength of hydrogen bonds formed between urea/urethane groups of hard segments and polyester or polyether groups of soft segments. Gel permeation chromatography measurements show that the molar mass of linear PesURUs markedly decreases with the hydrolysis time, whereas that of linear PetURUs remains almost unaffected. PesURU crosslinked by polymeric isocyanate has lower crystallinity, but shows somewhat better resistance to hydrolysis than its linear counterpart because of its more stable three-dimensional molecular structure. Water uptake at 37°C, dynamic mechanical thermal analysis, and differential scanning calorimetry thermograms determined for redried hydrolyzed specimens concurrently show that advancing hydrolysis accounts for decrease in the crystallinity (if any) of soft polyester segments, in the efficacy of hydrogen bonding and in crosslinking density. Experimental data indicate that hydrolytic resistance of PetURUs is primarily determined by (1) the hydrolytic stability of individual types of present groups, (2) steric hindrances affecting the access of water molecules to these groups, and (3) the hydrophilicity of backbones. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 577–586, 1998     

Melting and crystallization behaviour of elastoplastic semicrystalline copolymers: poly(ether ester)

The melting and crystallization behaviour of an elastoplastic semi-crystalline poly(etherester) has been studied by differential scanning calorimetry. The shape of the melting endotherm is strongly dependent on heating rate and annealing time and results from the sum of simultaneous melting and crystallization phenomena. Samples prepared by different techniques, i.e. by solvent evaporation or by melt extrusion, behave very differently owing to specific crystal morphologies. By applying the Hoffman-Weeks plot, the equilibrium melting temperature has been extrapolated. The Avrami treatment allows the calculation of the index n and of the rate constant K from the isothermal kinetic data.     

Highly oriented block copoly(ether ester) by solid state extrusion

Summary A segmented block copoly(ether ester) based on poly(butylene terephthalate) as “hard” segments and on poly(oxytetramethylene) as “soft” segments was highly oriented by cold flow extrusion. Upon further stretching of the high modulus material, the crystallites are tilted by 34∘ with respect to the stretching direction and a four point small angle X-ray pattern is obtained.     

嵌段聚醚酯弹性纤维的老化及热分解

通过测定以PBT为硬段 ,聚乙二醇 (PEG)和聚丁二醇 (PTMG)为软段的嵌段聚醚酯弹性纤维在老化前后的特性粘数、断裂强度、断裂伸长率和弹性回复率的变化 ,发现添加抗氧剂能明显改善该弹性纤维的抗老化性能并提高纤维的力学性能和回弹性能 ;采用热失重测定了PBT -PTMG2嵌段聚醚酯弹性纤维的热分解性能 ,热分解动力学计算表明其热分解活化能较低 ,为 69.6kJ ,容易热分解 ,热分解为 1级反应     

The effect of lyophilization on the solvent extraction of lipid classes,fatty acids and sterols from the oysterCrassostrea gigas

The lipid class compositions of adult Pacific oysters [Crassostrea gigas (Thunberg)] were examined using latroscan thin-layer chromatography/flame-ionization detection (TLC/FID), and fatty acid compositions determined by capillary gas chromatography and gas chromatography/mass spectrometry (GC/MS). The fatty acid methyl esters were separated using argentation TLC and also analyzed as their 4,4-dimethyloxazoline derivatives using GC/MS. Major esterified fatty acids inC. gigas were 16∶0, 20∶5n−3, and 22∶6n−3. C₂₀ and C₂₂ nonmethylene interrupted (NMI) fatty acids comprised 4.5 to 5.9% of the total fatty acids. The NMI trienoic fatty acid 22∶3(7,13,16) was also identified. Very little difference was found in the proportions of the various lipid classes, fatty acids or sterols between samples of adult oysters of two different sizes. However, significant differences in some of the lipid components were evident according to the method of sample preparation used prior to lipid extraction with solvents. Lyophilization (freeze drying) of samples led to a significant reduction in the amounts of triacylglycerols (TG) extracted by solvents in two separate experiments (7.0 and 52.5% extracted). Extracts from lyophilized samples had less 16∶0, C₁₈ unsaturated fatty acids, and 24-ethylcholest-5-en-3β-ol, while C₂₀ and C₂₂ unsaturated fatty acids comprised a higher proportion of the total fatty acids. There was no significant change in the amounts of polar lipids, total sterols, free fatty acids or hydrocarbons observed in extracts from lyophilized samples relative to extracts from nonlyophilized samples. Addition of water to the freezedried samples prior to lipid extraction greatly improved lipid yields and resulted in most of the TG being extracted.     

Influence of soft segment content and chain length on the physical properties of poly(ether ester) elastomers and fabrication of honeycomb pattern and electrospun fiber

Different series of poly(ether ester) (PEE) thermoplastic elastomers were synthesized using dimethyl-2,6-naphthalene dicarboxylate as hard segment, 1,4-butanediol as the chain extender, and three different soft segments of different molecular weights (MW), namely polycaprolactone diol (MW: 530 and 2000), poly(tetramethylene ether glycol) (MW: 1000 and 1800), and polycaprolactone-block-polytetrahydrofuran-block-polycaprolactone (MW: 2000). The composition of soft segment was changed from 30% to 50% with respect to the hard segment. The characteristic studies were focused to analyze the influence of the concentration and length of the soft segment content. In each series, 50:50 compositions of the hard and soft segments were found to show the best mechanical properties. In addition the physical properties of the elastomer were very sensitive to the type of soft segment. The elastomers prepared in this study were systematically characterized using various spectroscopic studies and thermal and mechanical analyses. As a means of discovering the feasibility of PEE elastomers as new functional materials honeycomb patterns and nanofibers have been fabricated by applying breath figures method and electrospinning, respectively, yielding uniform honeycomb structures and nanofibers of their diameter ranging from about 100 to 800 nm depending on the type of elastomer and the electrical potential employed .