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91.
Angelo Cichelli Ylenia Riciputi Lorenzo Cerretani Maria F. Caboni Nicola d'Alessandro 《Journal of the American Oil Chemists' Society》2020,97(1):15-23
A series of authentic virgin, refined, and mixtures of olive oils was analyzed for their content of 2-and 3-chloropropanediol (MCPD) esters expressed as 2−/3-MCPD, glycidol (and related glycidyl esters) (GE), and diglycerides (DAG). High concentrations of MCPD and GE were found, above all, in pomace oils, which come from the poorer starting raw materials, while virgin olive oils, as expected, do not contain any process contaminant. On the other hand, DAGs are present in all samples, demonstrating that their involvement in the formation of such contaminants only occurs when temperatures are higher than that used during the refining steps. The lack of correlation between the amounts of MCPD and GE can be ascribed to their completely different chemical stability as the epoxy ring of the GE opens easily, leading to both short-chain derivatives and/or MCPD itself. This finding can also explain the data about the absence of 2-MCPD in all the analyzed oil samples: other than the statistical probability and the steric effect of the SN2 formation mechanism, both in favor of the 3- derivative, we have also to consider the MCPD formation pathway involving glycidol that, under opportune conditions of refining, can increase the whole amount of 3-MCPD (under thermodynamic control, 3-MCPD is more stable). 相似文献
92.
Nicola A. Irvine Bente Ruyter Tone-Kari Østbye Anna K. Sonesson Karen A. Lillycrop Gerd Berge Graham C. Burdge 《Lipids》2019,54(11-12):725-739
Adequate dietary supply of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) is required to maintain health and growth of Atlantic salmon (Salmo salar). However, salmon can also convert α-linolenic acid (18:3n-3) into eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) by sequential desaturation and elongation reactions, which can be modified by 20:5n-3 and 22:6n-3 intake. In mammals, dietary 20:5n-3 + 22:6n-3 intake can modify Fads2 expression (Δ6 desaturase) via altered DNA methylation of its promoter. Decreasing dietary fish oil (FO) has been shown to increase Δ5fad expression in salmon liver. However, it is not known whether this is associated with changes in the DNA methylation of genes involved in polyunsaturated fatty acid synthesis. To address this, we investigated whether changing the proportions of dietary FO and vegetable oil altered the DNA methylation of Δ6fad_b, Δ5fad, Elovl2, and Elovl5_b promoters in liver and muscle from Atlantic salmon and whether any changes were associated with mRNA expression. Higher dietary FO content increased the proportions of 20:5n-3 and 22:6n-3 and decreased Δ6fad_b mRNA expression in liver, but there was no effect on Δ5fad, Elovl2, and Elovl5_b expression. There were significant differences between liver and skeletal muscle in the methylation of individual CpG loci in all four genes studied. Methylation of individual Δ6fad_b CpG loci was negatively related to its expression and to proportions of 20:5n-3 and 22:6n-3 in the liver. These findings suggest variations in dietary FO can induce gene-, CpG locus-, and tissue-related changes in DNA methylation in salmon. 相似文献
93.
94.
Nicola A. Suttle 《Materials & Design》1988,9(6):318-324
Piezoelectricity and pyroelectricity, traditionally encountered in single crystals and ceramics, have now been documented in a number of polymers. The most successful and widely used polymer is polyvinylidene fluoride (PVF2) which has been shown to be ferroelectric. The copolymers of PVF2 with related fluorinated vinyl monomers also exhibit piezoelectric activity and those with trifluoroethylene (VF3) show enhanced activity over the homopolymer. These particular copolymers crystallize into an intrinsically piezoelectric crystal phase from the melt and thus offer advantages in processing and potential application.
This paper compares piezoelectric constants obtained for commercially available PVF2 with those for a series of PVF2/VF3 copolymers. One copolymer shows a 50 per cent increase in activity over PVF2 when evaluated as a hydrophone material. The chemistry of alternative piezoelectric polymers is described. Areas of application of these exciting new materials are presented. 相似文献
95.
96.
ABSTRACT: Adequate cooking of meat is necessary to inactivate microbial pathogens. This is particularly important for ground meat products and some variety meats where pathogens can be present internally. Consumers are being advised on appropriate temperatures to which meat products should be cooked, and to use a meat thermometer to ensure these temperatures are reached. However, consumers are more likely to assess cooking status by the color of the meat or juice. This article reviews the factors that can influence the final color of cooked meat. In most instances, these factors influence color by modifying the meat pigment myoglobin prior to and during cooking. Many factors can prolong the pink "uncooked" color in meat, including high pH, modified atmosphere packaging, rapid thawing, low fat content, nitrite, and irradiation. Such factors may lead to overcooking and loss of food quality, and consumer rejection. Alternatively, factors that cause "premature browning" of meat, where the interior of the product looks cooked but a microbiologically safe temperature has not been reached, are food safety issues. Pale, soft exudative meats can prematurely brown, as can meats packaged under oxygenated conditions, frozen in bulk or thawed over long periods, or those that have had salts or lean finely textured beef added. Meats cooked from a frozen state or irradiated in aerobic conditions might also be at risk, but this might depend on meat species. In summary, the color of cooked meat is not a good indicator of adequate cooking, and the use of a food thermometer is recommended. 相似文献
97.
A Nicola Wootton Martin Luker-Brown Roger J Westcott Peter S J Cheetham 《Journal of the science of food and agriculture》1993,61(4):429-433
Abstract : A process for the micropropagation of Amorphophallus rivierii (elephant yam or konjac) and for the extraction and purification of the glucomannan polysaccharide from fresh konjac plant corms has been developed. This process involves extraction with 2-propanol, which has the additional benefit of extracting carotenoids as a potentially valuable side-product. Starch granules with an unusually high and homogeneous gelatinisation temperature range are normally present in the corms, particularly immature ones, and this greatly reduces the strength of gels formed using the glucomannan. Therefore, the extraction process also involves the selective hydrolysis of the starch, by α- and β-amylases that have been specially selected for an absence of contaminating β-mannanase or β-glucanase activity that would depolymerise the glucomannan and render it nonfunctional. Bacillus lichenformis α-amylase was preferred. Using this process pure glucomannan could be extracted which, when mixed with K -carrageenan, forms a gel almost twice as strong as locust bean gum-K -carrageenan gels of the same concentration. 相似文献
98.
Vallati Carlo Mingozzi Enzo Tanganelli Giacomo Buonaccorsi Novella Valdambrini Nicola Zonidis Nikolaos Martínez Belén Mamelli Alessandro Sommacampagna Davide Anggorojati Bayu Kyriazakos Sofoklis Prasad Neeli Nieto Francisco Javier Rodriguez Oliver Barreto 《Wireless Personal Communications》2016,87(3):1071-1091
Wireless Personal Communications - The integration of everyday objects into the Internet represents the foundation of the forthcoming Internet of Things (IoT). Smart objects will be the building... 相似文献
99.
Muhammad Hamid Raza Kaveh Movlaee Salvatore Gianluca Leonardi Nicolae Barsan Giovanni Neri Nicola Pinna 《Advanced functional materials》2020,30(6)
Hierarchical core–shell (C–S) heterostructures composed of a NiO shell deposited onto stacked‐cup carbon nanotubes (SCCNTs) are synthesized by atomic layer deposition (ALD). A film of NiO particles (0.80–21.8 nm in thickness) is uniformly deposited onto the inner and outer walls of the SCCNTs. The electrical resistance of the samples is found to increase of many orders of magnitude with the increasing of the NiO thickness. The response of NiO–SCCNT sensors toward low concentrations of acetone and ethanol at 200 °C is studied. The sensing mechanism is based on the modulation of the hole‐accumulation region in the NiO shell layer upon chemisorption of the reducing gas molecules. The electrical conduction mechanism is further studied by the incorporation of an Al2O3 dielectric layer at NiO and SCCNT interfaces. The investigations on NiO–Al2O3–SCCNT, Al2O3–SCCNT, and NiO–SCCNT coaxial heterostructures reveal that the sensing mechanism is strictly related to the NiO shell layer. The remarkable performance of the NiO–SCCNT sensors toward acetone and ethanol benefits from the conformal coating by ALD, large surface area of the SCCNTs, and the optimized p‐NiO shell layer thickness followed by the radial modulation of the space‐charge region. 相似文献
100.
Alessandra Bosutti Barbara Dapas Gabriele Grassi Rossana Bussani Fabrizio Zanconati Fabiola Giudici Cristina Bottin Nicola Pavan Carlo Trombetta Bruna Scaggiante 《International journal of molecular sciences》2022,23(8)
Although the eukaryotic elongation factor eEF1A1 plays a role in various tumours, there is little information on its prognosis/therapeutic value in prostate carcinoma. In high-grade and castration-resistant prostate carcinoma (CRPC), the identification of novel therapeutic markers/targets remains a priority. The expression of eEF1A1 protein was determined in formalin-fixed, paraffin-embedded prostate cancer and hyperplasia tissue by IHC. The role of eEF1A1 was investigated in a cellular model using a DNA aptamer (GT75) we previously developed. We used the aggressive CRPC cancer PC-3 and non-tumourigenic PZHPV-7 lines. Cytotoxicity was measured by the MTS assay and eEF1A1 protein levels by in-cell Western assays. The mRNA levels of eEF1A1 were measured by qPCR and ddPCR. Higher expression of eEF1A1 was found in Gleason 7–8 compared with 4–6 tissues (Gleason ≥ 7, 87% versus Gleason ≤ 6, 54%; p = 0.033). Patients with a high expression of eEF1A1 had a worse clinical outcome. In PC-3, but not in PZHPV-7, GT75 decreased cell viability and increased autophagy and cell detachment. In PC-3 cells, but not in PZHPV-7, GT75 mainly co-localised with the fraction of eEF1A1 bound to actin. Overexpression of the eEF1A1 protein can identify aggressive forms of prostate cancer. The targeting of eEF1A1 by GT75 impaired cell viability in PC-3 cancer cells but not in PZHPV-7 non-tumourigenic cells, indicating a specific role for the protein in cancer survival. The eEF1A1–actin complexes appear to be critical for the viability of PC-3 cancer cells, suggesting that eEF1A1 may be an attractive target for therapeutic strategies in advanced forms of prostate cancer. 相似文献