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排序方式: 共有178条查询结果,搜索用时 625 毫秒
91.
Charged lepton flavor violation (CLFV) is a clear signal of new physics; it directly addresses the physics of flavor and of generations. The search for CLFV has continued from the early 1940s, when the muon was identified as a separate particle, until today. Certainly in the LHC era the motivations for continued searches are clear and have been covered in many reviews. This review is focused on the experimental history with a view toward how these searches might progress. We examine the status of searches for charged lepton flavor violation in the muon, tau, and other channels, and then examine the prospects for new efforts over the next decade. Finally, we examine what paths might be taken after the conclusion of upcoming experiments and what facilities might be required. 相似文献
92.
Abstract High pressures ranging 50 to 400 MPa were applied to Gouda cheese cylinders and evolution of the volatile fraction was followed during three weeks. No new volatiles were recovered after simultaneous distillation-extraction, but some effects of high pressure on the fermentation processes were observed. Thus butyric acid and acetoin were found in lower concentrations after ripening of pressurized samples. Nevertheless differences in the volatile profile were not large enough to suggest an effect of high pressure on the acceleration of Gouda cheese ripening. 相似文献
93.
For exploring the influence of ultrasound on the flavor characteristic of unsmoked bacon, sensory evaluation combined with E-nose and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) were performed to analyze the overall flavor profile and specific volatile flavor compounds (VFCs), respectively. Furthermore, the metabolic pathway of VFCs affected by ultrasound was also investigated. Results demonstrated that ultrasound improved the flavor characteristic of unsmoked bacon by raising the levels of nonanal, heptanal, octanal, 3-methylbutanal n-hexyl acetate and n-propyl acetate. Enzymatic oxidation was found to be an important metabolic pathway responsible for the development of flavor characteristic after ultrasound treatment, which could be attributed to the increased activities of lipases and lipoxygenase and the higher concentration of polyunsaturated free fatty acids. The increased level of lipid oxidation after ultrasound treatment was also confirmed by thiobarbituric acid reactive substances. Consequently, ultrasound is an effective approach to enhance the flavor characteristic of unsmoked bacon. 相似文献
94.
Valentina Canuti Michael Conversano Marco Li Calzi Hildegarde Heymann Mark A. Matthews Susan E. Ebeler 《Journal of chromatography. A》2009,1216(15):3012-3022
The complex aroma of wine is derived from many sources, with grape-derived components being responsible for the varietal character. The ability to monitor grape aroma compounds would allow for better understanding of how vineyard practices and winemaking processes influence the final volatile composition of the wine. Here, we describe a procedure using GC–MS combined with headspace solid-phase microextraction (HS-SPME) for profiling the free volatile compounds in Cabernet Sauvignon grapes. Different sample preparation (SPME fiber type, extraction time, extraction temperature and dilution solvent) and GC–MS conditions were evaluated to optimize the method. For the final method, grape skins were homogenized with water and 8 ml of sample were placed in a 20 ml headspace vial with addition of NaCl; a polydimethylsiloxane SPME fiber was used for extraction at 40 °C for 30 min with continuous stirring. Using this method, 27 flavor compounds were monitored and used to profile the free volatile components in Cabernet Sauvignon grapes at different maturity levels. Ten compounds from the grapes, including 2-phenylethanol and β-damascenone, were also identified in the corresponding wines. Using this procedure it is possible to follow selected volatiles through the winemaking process. 相似文献
95.
M. Pierini 《Progress in Particle and Nuclear Physics》2009,62(1):1-47
The vast amount of flavor physics data available to date allows probing the presence of physics beyond the standard model through precision measurements of CP violating and CP conserving processes involving B, D, and K mesons. The information extracted from these measurements allows the characterization of physics beyond the standard model in a complementary way with respect to the direct searches at the Tevatron and the LHC. We review the status of the search for new physics with flavor-related observables. We discuss the status of the unitarity triangle analysis beyond the standard model: the inclusion of the recent measurements of Bs decays from the Tevatron experiments point to a discrepancy from the standard model expectation. In addition, we discuss the impact of O(ΛQCD/mb) corrections to the perturbative calculation of charmless hadronic B decays. These corrections can explain the puzzling values of direct CP asymmetries in B→Kπ decays within the standard model. These corrections cannot explain values of sin2β lower than the standard model value, as observed in b→s penguin decays. We conclude with the perspectives of the next generation of flavor-physics experiments, the precision they can reach and their phenomenological impact. 相似文献
96.
The research concerns the use of proton transfer reaction mass spectrometer to track real-time emissions of volatile secondary oxidation products released from rapeseed oil as a result of deep-frying of potato cubes. Therefore, it was possible to observe a sudden increase of volatile organic compound (VOC) emissions caused by immersion of the food, accompanied by a sudden release of steam from a potato cube and a decrease of the oil temperature by more than 20 °C. It was possible to identify and monitor the emission of major secondary oxidation products such as saturated and unsaturated aldehydes, namely acrolein, pentanal, 2-hexenal, hexanal, 2-nonenal and 2-decenal. Each of them has an individual release characteristic. Moreover, the impact of different initial frying temperatures on release kinetics was investigated. Subsequently, it was possible to approximate the cumulative emission by a second-degree polynomial (R2 ≥ 0.994). Using the proposed solution made it possible for the first time to observe the impact of the immersion of food in vegetable oil on the early emission of thermal degradation products oil. 相似文献
97.
98.
Martina Machov Tom Bajer David ilha Karel Ventura Petra Bajerov 《Molecules (Basel, Switzerland)》2021,26(24)
The volatile components of areca nuts were isolated by headspace solid-phase microextraction (HS-SPME, DVB/CAR/PDMS fiber extraction) and simultaneous hydrodistillation–extraction (SHDE) and analyzed by gas chromatography/mass spectrometry. Furthermore, all SHDE fractions were tested for antimicrobial activity using the disk diffusion method on nine Gram-negative and Gram-positive bacteria (Bacillus subtilis, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus canis, Streptococcus pyogenes, and Candida albicans). In total, 98 compounds (mainly alcohols, carbonyl compounds, fatty acids, esters, terpenes, terpenoids, and aliphatic hydrocarbons) were identified in SHDE fractions and by using SPME extraction Fatty acids were the main group of volatile constituents detected in all types of extracts. The microorganism most sensitive to the extract of the areca nut was Streptococcus canis. The results can provide essential information for the application of different treatments of areca nuts in the canning industry or as natural antibiotics. 相似文献
99.
Dong-Sik Yang Zhentian Lei Mohamed Bedair Lloyd W. Sumner 《Molecules (Basel, Switzerland)》2021,26(21)
Solid-phase microextraction (SPME) was coupled to gas chromatography mass spectrometry (GC-MS) and a method optimized to quantitatively and qualitatively measure a large array of volatile metabolites in alfalfa glandular trichomes isolated from stems, trichome-free stems, and leaves as part of a non-targeted metabolomics approach. Major SPME extraction parameters optimized included SPME fiber composition, extraction temperature, and extraction time. The optimized SPME method provided the most chemically diverse coverage of alfalfa volatile and semi-volatile metabolites using a DVB/CAR/PDMS fiber, extraction temperature of 60 °C, and an extraction time of 20 min. Alfalfa SPME-GC-MS profiles were processed using automated peak deconvolution and identification (AMDIS) and quantitative data extraction software (MET-IDEA). A total of 87 trichome, 59 stem, and 99 leaf volatile metabolites were detected after background subtraction which removed contaminants present in ambient air and associated with the fibers and NaOH/EDTA buffer solution containing CaCl2. Thirty-seven volatile metabolites were detected in all samples, while 15 volatile metabolites were uniquely detected only in glandular trichomes, 9 only in stems, and 33 specifically in leaves as tissue specific volatile metabolites. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) of glandular trichomes, stems, and leaves showed that the volatile metabolic profiles obtained from the optimized SPME-GC-MS method clearly differentiated the three tissues (glandular trichomes, stems, and leaves), and the biochemical basis for this differentiation is discussed. Although optimized using plant tissues, the method can be applied to other types of samples including fruits and other foods. 相似文献
100.