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排序方式: 共有2319条查询结果,搜索用时 453 毫秒
131.
J. Vacik V. Hnatowicz J. Cervena H. Naramoto S. Yamamoto D. Fink 《Fullerenes, Nanotubes and Carbon Nanostructures》2001,9(2):197-209
To determinate the stopping cross section in fullerite a feasible approach, taking into account the high radiation sensitivity and mechanical fragility of fullerite films, should be employed. In this work, the stopping cross sections of 1H, 3H, 4He and 7Li ions for several selected energies were measured by Rutherford backscattering, neutron depth profiling and alpha spectroscopy using sandwich structures of samples composed of fullerite deposited on a firm substrate (Si, steel) with an intermediate marker (Au, N, Li, B, Pu). In addition, ion transmission through a thin C film supporting a fullerite layer was also utilized. The measured stopping cross sections follow the theoretical predictions calculated for carbon, but are systematically (10-35%) higher than the theoretical ones (with the exception of 5 — 5.5 MeV 4He). The observed deviation of the experimental data can partly be explained by the chemical state effects in fullerite, which accounts for about 20-50% of the difference. The measured energy straggling exceeds Bohr's value by a factor of about 2 for alpha spectroscopy and ion transmission, and 2.5 or 9.5 for Rutherford backscattering and neutron depth profiling, respectively. The discrepancy can be explained by a thickness variation, such as surface roughness of the fullerite films. 相似文献
132.
K.H. Sabeena Farvin S. Hari Senthil KumarR. Anandan Suseela MathewT.V. Sankar P.G. Viswanathan Nair 《Food chemistry》2007,105(4):1390-1395
We have investigated the preventive effects of squalene against isoprenaline-induced myocardial infarction in male albino rats. Supplementation with squalene significantly prevented the isoprenaline-induced adverse changes in the levels of protein and glycoprotein components in plasma and heart tissue of experimental groups of rats. It exerted an antioxidant effect by inhibiting the isoprenaline-induced lipid peroxidation and by maintaining the level of non-enzymatic free radical-scavenger, reduced glutathione at near normalcy. Histopathological observations also confirmed the possible cardioprotective action of squalene by maintaining the normal architecture of the heart tissue. The results of the present investigation demonstrate that supplementation with squalene offers cardioprotection in experimental rats by its antioxidant and membrane- stabilizing properties. 相似文献
133.
Amonrat Thanonkaew Soottawat Benjakul Wonnop Visessanguan Eric A. Decker 《Food chemistry》2007,102(1):219-224
Lipid oxidation, discoloration, loss of amine groups and pyrrolization of the liposome systems of cuttlefish (Sepia pharaonis) in the presence of FeCl3 and ascorbic acid were studied. Thiobarbituric acid-reactive substances (TBARS) and the b∗-value of cuttlefish liposomes increased with a coincidental decrease in amine groups when the incubation temperatures (0, 4, 25, and 37 °C) and incubation times (0–24 h) were increased (p < 0.05). As lipid oxidation and yellow pigment formation in the cuttlefish liposome proceeded, a loss of amine groups and pyrrolization were also detected. The effects of FeCl3 and ascorbic acid, at different concentrations, on TBARS production, b∗-value, loss of amine groups and pyrrolization of cuttlefish liposome were also investigated. Both FeCl3 and ascorbic acid showed prooxidative effects in cuttlefish liposome in a concentration-dependent manner. Sodium chloride (0–2%) reduced TBARS, b∗-values and pyrrole compounds. These results suggest a positive correlation between lipid oxidation and the development of yellow pigments in cuttlefish phospholipids. 相似文献
134.
Ahmed E.M. Abdalla Saeid M. DarwishEman H.E. Ayad Reham M. El-Hamahmy 《Food chemistry》2007,103(4):1134-1140
Egyptian mango seeds were collected as wastes from local fruit processing units and the kernels were separated and dried. This study was carried out on mango seed kernels to clarify their proximate composition, amino acids, phenolic compounds and the characteristics of the extracted oil including unsaponifiable matter constituents, lipid classes and fatty acid composition. Mango seed kernels contained a considerable amount of total phenolic compounds, total lipid, unsaponifiable matter, and a low amount of crude protein, but the quality of protein was good because it was rich in all essential amino acids. Eight phenolic compounds were identified; tannin and vanillin were in highest amounts. Unsaponifiable matter showed the occurrence of high amounts of squaline followed by sterols and tocopherols. Stearic acid was the main saturated fatty acid, while oleic acid was the major unsaturated fatty acid in all lipid classes. The fatty acid composition of total lipid and neutral lipid was similar, while phospholipid had a high amount of palmitic, linoleic and linolenic acids. 相似文献
135.
Radiation induced molecular changes in macromolecular components of hazelnut tissues were investigated by mid-Fourier transform infrared (FTIR) spectroscopy. Irradiation dose of 1.5 kGy (low) and 10 kGy (high) were applied. The changes in frequency, signal intensity and intensity ratio of IR bands revealed that the unsaturated lipid concentration increased for low dose treated samples whereas it decreased and peroxidation appeared at high dose treatment. The low dose irradiation treatment, slightly increased the total lipid content whereas it dramatically decreased for high dose treatment. A slight increase in the lipid to protein ratio was observed for low dose treatment, whilst this ratio significantly decreased for high dose treatment. In addition, the high dose γ-irradiation caused alterations in the structure of hazelnut proteins, as cross-linking and aggregation occured in protein molecules. These results indicate that FTIR spectroscopy can be successfully used to monitor food irradiation. 相似文献
136.
Arantxa Rodriguez-Casado Pedro Carmona Pilar Moreno Ignacio Sánchez-González Antonella Macagnano Corado Di Natale Mercedes Careche 《Food chemistry》2007,103(3):1024-1030
Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy has been used for the first time to evaluate the postmortem changes in structure of components from sardine muscle in relation to quality loss. Sardines (Sardina pilchardus) were stored in ice for up to thirteen days. The spectroscopic study was focussed on the structural changes produced on the lipids and proteins. 相似文献
137.
Mohamed Fawzy Ramadan Mohamed Mostafa Afify Amer Ahmed El-Said Awad 《European Food Research and Technology》2008,227(4):1173-1182
Coriander (Coriandrum sativum L.) seed oil (COR) is a promising oil with high levels of bioactive compounds. Very little information, however, is available
on the effect of administration of COR on different aspects of plasma lipid profile in experimental animals. In view of the
important implications, the effect of administration of COR and oil blend [a mixture of soybean oil, coriander oil and sunflower
oil (4:2:4, w/w/w; Blend)] on the profile of plasma lipids was investigated in 24 male albino rats placed on a cholesterol-rich
(1%) basal diet as compared to rats on a cholesterol-free basal diet. Coriander seed oil and Blend were analyzed for composition
of fatty acid, sterol and tocopherol. The levels of bioactive compounds (sterols and tocopherols) were higher in COR than
in the Blend. In addition, the antiradical potential of COR and Blend was measured and the results showed that COR had stronger
radical scavenging activity than Blend. In the biological experiment, rats were divided into four diet groups. The negative
control group (control) consumed the basal diet (BD) only, which contained wheat starch, casein and cellulose, as well as
mineral and vitamin mixtures. To the BD were added 1 g/100 g cholesterol (Chol/group), or both (Chol/COR group) and (Chol/Blend
group). The groups did not differ before the experiment, which lasted 60 days. Plasma total lipids (TL), triacylglycerols
(TAG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol (HDL-C) were measured at day 15, 30, 45 and 60 during the experiment period. Generally, COR and Blend-supplemented diets decreased
the levels of TL, TC, TAG and LDL-C in plasma. In addition, significant increase in the levels of HDL-C was observed for Chol/COR
and Chol/Blend groups. The results demonstrated that COR, and to a relatively lesser degree Blend, have hypocholesterolemic
properties in rats fed a cholesterol-rich diet. 相似文献
138.
Effect of the long-term intake of an egg white hydrolysate on the oxidative status and blood lipid profile of spontaneously hypertensive rats 总被引:1,自引:0,他引:1
María A. Manso Marta Miguel Jeanne Even Rosario Hernández Amaya Aleixandre Rosina López-Fandiño 《Food chemistry》2008
This paper examines the effects of the long-term consumption of egg white hydrolysed with pepsin (hEW) on the antioxidant status and lipid profile of spontaneously hypertensive rats (SHR). The antioxidant capacity was measured by the oxygen radical absorbance capacity (ORAC) and the oxidative status by the malon-dialdehyde (MDA) assay. The lipid profile was analysed spectrophotometrically. The radical-scavenging capacity of the plasma was increased and the MDA concentration in the aorta was decreased in the SHR treated with 0.5 g/kg/day of hEW. Our findings indicate that hEW played an important role in antioxidative defence of SHR and exerted a beneficial effect on the lipid profile, lowering triglycerides and total cholesterol without changing HDL levels. Therefore, hEW may be useful to prevent or reverse abnormalities associated with the metabolic syndrome and its complications, such as hypertension, oxidative stress and hyperlipidemia. 相似文献
139.
Whole grain condensed tannin sorghum, its bran and a crude phenolic extract (CPE) prepared from the bran were evaluated for total phenols (TP), condensed tannins (CT) and antioxidant activity (AA). Antioxidant effect of the CPE from the sorghum bran was evaluated in sunflower oil in the presence of ferric ions by measuring peroxide values (PVs) and anisidine values (AVs) during storage at 65 °C, in comparison with tertiary butyl hydroquinone (TBHQ). Sorghum bran contained three times more TP and AA, and seven times more CT than the whole grain. The CPE had highest levels of TP, CT and AA. Sunflower oil with CPE had lower PVs and AVs compared to control samples. Oil samples with TBHQ had PVs lower than, but AVs similar to samples containing CPE. In the presence of ferric ions, the CPE was less effective in reducing PVs, but was more effective than TBHQ in reducing AVs. 相似文献
140.
This study was carried out to evaluate the chemical changes and sensory attributes of Pacific saury (Cololabis saira), brined (12% NaCl brine solution) or marinated (12% NaCl + 2% acetic acid; or 12% NaCl + 3% acetic acid solutions) followed by vacuum-packaging and storage at 4 °C for 90 days. The chemical analysis revealed a significant reduction in the pH value, total volatile bases nitrogen (TVBN), and trimethylamine (TMA) contents in marinated versus brined fillets. Lipid oxidation, as indicated by the 2-thiobarbituric acid (TBA) values, was significantly delayed in marinated fillets in comparison with the brined fillets. The growth rate of psychrotrophic bacteria was significantly (P < 0.05) reduced in marinated versus brined fillets. No significant differences were detected for the sensory attributes between the two marinating conditions although the overall acceptability was significantly higher in marinated versus brined fish. Both conditions of the marinating process resulted in an extension of the shelf life of the product to more than 90 days versus only 60 days for the control brined fillets. The study concluded that marination of Pacific saury can delay the undesirable chemical changes, retard lipid oxidation, improve the sensory attributes and extend the shelf life of the product during refrigerated storage. 相似文献