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491.
Specific susceptibility of docosahexaenoic acid and eicosapentaenoic acid to peroxidation in aqueous solution 总被引:3,自引:0,他引:3
The peroxidation of different polyunsaturated fatty acids (PUFA) after photoirradiation in aqueous solution was evaluated
by measuring fatty acid loss and malonaldehyde production in medium. The oxidation rates of eicosapentaenoic acid (EPA) and
docosahexaenoic acid (DHA), two highly unsaturated fatty acids of the n−3 series, were surprisingly lower (14 and 22%, respectively)
than the oxidation rates of linoleic, α-linolenic, γ-linolenic, dihomo γ-linolenic, and arachidonic acids (62–90%). The quantities
of malonaldehyde (MA) produced were assayed simultaneously by gas chromatography (GC) and high performance liquid chromatography
(HPLC). MA production was found to be related to both the degree of unsaturation and the metabolic series of the fatty acid.
The maximum value was observed with arachidonic acid (MA production from 2 mM arachidonic acid in aqueous solution was estimated
at 44.9±6.0 μM by GC and 46.8 ±4.0 μM by HPLC). Eicosapentaenoic acid and docosahexaenoic acid produced lower MA quantities
compared to arachidonic acid (MA production from 2 mM EPA and 2 mM DHA was estimated at 17.9±1.5 μM and 37.9±0.7 μM, respectively,
by GC, and 26.3±4.9 μM and 37.3±4.2 μM, respectively, by HPLC). The MA yield, defined as the amount of MA (nmols) produced
per 100 nanomoles of oxidized fatty acid, was used to express the susceptibility of individual PUFA to peroxidation. The MA
yield correlated well with the degree of unsaturation, but was independent of carbon chain length and metabolic series. The
study suggests that adequate assessment of lipid peroxidation cannot be achieved by measuring MA formation alone, but it also
requires knowledge of the fatty acid composition of the system studied. 相似文献
492.
Anh Minh Huynh Andreas Müller Sonja M. Kessler Sarah Henrikus Caroline Hoffmann Alexandra K. Kiemer Arno Bücker Gregor Jung 《ChemMedChem》2016,11(14):1568-1575
The combination of the two complementary imaging modalities 19F magnetic resonance imaging (MRI) and fluorescence imaging (FLI) possesses high potential for biological and medical applications. Herein we report the first design, synthesis, dual detection validation, and cytotoxic testing of four promising BODIPY dyes for dual 19F MRI–fluorescence detection. Using straightforward Steglich reactions, small fluorinated alcohols were easily covalently tethered to a BODIPY dye in high yields, leaving its fluorescence properties unaffected. The synthesized compounds were analyzed with various techniques to demonstrate their potential utility in dual imaging. As expected, the chemically and magnetically equivalent trifluoromethyl groups of the agents exhibited a single NMR signal. The determined longitudinal relaxation times T1 and the transverse relaxation times T2, both in the lower second range, enabled the imaging of four compounds in vitro. The most auspicious dual 19F MRI–fluorescence agent was also successfully imaged in a mouse post‐mortem within a 9.4 T small‐animal tomograph. Toxicological assays with human cells (primary HUVEC and HepG2 cell line) also indicated the possibility for animal testing. 相似文献
493.
Huynh Cang Mai Ngoc Duy Dao Tri Duc Lam Bao Viet Nguyen Duy Chinh Nguyen Long Giang Bach 《Journal of the American Oil Chemists' Society》2019,96(11):1303-1311
This study presented a refining process and reported on fatty acid composition and the physicochemical properties of the oil from black soldier fly larvae (BSFL). Crude larvae oil was purified through four steps consisting of degumming, neutralization, bleaching, and deodorization. Optimum degumming conditions that give the highest phospholipid weight and oil consisted of water concentration of 7% (v/v), followed by addition of H2SO4 at a concentration of 0.5% (v/v). Optimum conditions for saponification that maximize saponification value and free fatty acid (FFA) value were 0.4 mg NaOH/100 g oil, 1 hour, and 80 °C of NaOH quantity, reaction time, and temperature, respectively. The oil was then dehydrated using 10 mg Na2SO4/g oil. The bleaching process that gives maximum oil yield consisted of activated carbon at concentration of 5% (w/w), followed by centrifugation at a speed of 5000 rpm (radius = 86 mm) for 30 min. The contents of lauric acid, linoleic acid, and linolenic acid in purified oil were 28.8%, 11.1%, and 0.4%, respectively. Physicochemical properties of the refined oil included viscosity of 96 ± 0.14 cP (measured at 20 °C), FFA value of 0.45 ± 0.017%, acid value of 0.9 ± 0.043 mg KOH g−1, saponification value of 215.78 mg KOH g−1, iodine value of 53.7 gI2/100 g, and peroxide index of 133 mEq kg−1. 相似文献
494.
Combined puncture/cutting of elastomer membranes by pointed blades: Characterization of mechanisms 下载免费PDF全文
The simultaneous puncture and cutting behavior of elastomers was investigated by pointed blades. Puncture/cutting tests by three‐pointed blades were performed with different elastomer membranes, including butyl, neoprene, and nitrile rubbers. The fracture mechanisms associated to puncture/cutting were investigated. The quantitative material properties which control the puncture/cutting resistance are obtained. The results have showed that the crack growth propagation is controlled by the material viscoelastic and the fracture behaviors of material, as well as the friction between the pointed blade and material. As evidenced from the fracture mechanism analysis, the friction contributes to the resistance of material against the simultaneous puncture and cutting by a factor of more than 60%. It has also been that the penetration force and the global fracture energy depend on the blade tip angle, the cutting edge angle, and the blade lubrication. Finally, an analysis of mixed‐mode fracture based on puncture/cutting by pointed blades has been described. The crack propagation is a synergistic interaction between the fracture modes I and III. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42150. 相似文献
495.
496.
Aleksandra Rudnitskaya Dmitry A. Borkin Ken Huynh Béla Török Prof. Kimberly Stieglitz Prof. 《ChemMedChem》2010,5(3):384-389
By using computer modeling and lead structures from our earlier SAR results, a broad variety of pyrrole‐, indole‐, and pyrazole‐based compounds were evaluated as potential fructose 1,6‐bisphosphatase (FBPase) inhibitors. The docking studies yielded promising structures, and several were selected for synthesis and FBPase inhibition assays: 1‐[4‐(trifluoromethyl)benzoyl]‐1H‐indole‐5‐carboxamide, 1‐(α‐naphthalen‐1‐ylsulfonyl)‐7‐nitro‐1H‐indole, 5‐(4‐carboxyphenyl)‐3‐phenyl‐1‐[3‐(trifluoromethyl)phenyl]‐1H‐pyrazole, 1‐(4‐carboxyphenylsulfonyl)‐1H‐pyrrole, and 1‐(4‐carbomethoxyphenylsulfonyl)‐1H‐pyrrole were synthesized and tested for inhibition of FBPase. The IC50 values were determined to be 0.991 and 1.34 μM , and 575, 135, and 32 nM , respectively. The tested compounds were significantly more potent than the natural inhibitor AMP (4.0 μM ) by an order of magnitude; indeed, the best inhibitor showed an IC50 value toward FBPase more than two orders of magnitude better than that of AMP. This level of activity is virtually the same as that of the best currently known FBPase inhibitors. This work shows that such indole derivatives are promising candidates for drug development in the treatment of type II diabetes. 相似文献
497.
Ngo Tran Min Young Lee Hong Hanh Nguyen Woo Hyun Jeong Ngoc Toan Dang Le Anh Thi The-Long Phan Bo Wha Lee 《Journal of the American Ceramic Society》2021,104(7):3376-3386
We prepared Ba3−xYxCo2Fe24O41 (Y-Co2Z, x = 0, 0.2, and 0.4) by the solid-state reaction method. Y-Co2Z and polyaniline (PANI) composites (named as Y-P0, Y-P2, and Y-P4) were prepared by using the in-situ polymerization method. The Y-doping played an important role in the variation of lattice parameters, a and c. The combination of Y-doping and PANI modified the magnetic properties of the composites, which could be observed by the changing of the saturation magnetization and coercivity. This combination had also affected the electromagnetic properties of composites through the measurements of complex permittivity and permeability. Using the transmission line theory, we calculated refection loss (RL) of composites with the variation thickness of 1.00–2.50 mm. Our composites tuned the minimum RL from the X band (RL = −29.6 dB at 11.4 GHz for Y-P2) to Ku band (RL = −16.3 dB at 15.7 GHz for Y-P4 and RL = −26.4 dB at 16.6 GHz for Y-P4). For maximum effective bandwidth, our composites covered a huge range from the S and C bands (Y-P0 with 3.9 GHz in the range of 3.4–7.3 GHz) through the X band (Y-P2 with 3.9 GHz in the range of 9.0–12.9 GHz) to the Ku band (Y-P4 with 4.0 GHz in the range of 13.8–17.8 GHz). Those properties proved that the composites could act as promising absorbers in the S, C, X, and Ku bands. 相似文献