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141.
Fortunati Alessandro Bacigalupo Andrea Lepidi Marco Arena Andrea Lacarbonara Walter 《Nonlinear dynamics》2022,108(2):765-787
Nonlinear Dynamics - The cellular microstructure of periodic architected materials can be enriched by local intracellular mechanisms providing innovative distributed functionalities. Specifically,... 相似文献
142.
Hammad Ullah Yaseen Hussain Cristina Santarcangelo Alessandra Baldi Alessandro Di Minno Haroon Khan Jianbo Xiao Maria Daglia 《Molecules (Basel, Switzerland)》2022,27(6)
Food spoilage makes foods undesirable and unacceptable for human use. The preservation of food is essential for human survival, and different techniques were initially used to limit the growth of spoiling microbes, e.g., drying, heating, salting, or fermentation. Water activity, temperature, redox potential, preservatives, and competitive microorganisms are the most important approaches used in the preservation of food products. Preservative agents are generally classified into antimicrobial, antioxidant, and anti-browning agents. On the other hand, artificial preservatives (sorbate, sulfite, or nitrite) may cause serious health hazards such as hypersensitivity, asthma, neurological damage, hyperactivity, and cancer. Thus, consumers prefer natural food preservatives to synthetic ones, as they are considered safer. Polyphenols have potential uses as biopreservatives in the food industry, because their antimicrobial and antioxidant activities can increase the storage life of food products. The antioxidant capacity of polyphenols is mainly due to the inhibition of free radical formation. Moreover, the antimicrobial activity of plants and herbs is mainly attributed to the presence of phenolic compounds. Thus, incorporation of botanical extracts rich in polyphenols in perishable foods can be considered since no pure polyphenolic compounds are authorized as food preservatives. However, individual polyphenols can be screened in this regard. In conclusion, this review highlights the use of phenolic compounds or botanical extracts rich in polyphenols as preservative agents with special reference to meat and dairy products. 相似文献
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145.
Despite the existence of an extensive literature, no definitive conclusion seems to emerge on the extent to which minorities are guaranteed by democratic rules in political systems. This paper contributes to this debate by proposing a modified Heigselmann and Krauss two-dimensional model of preferences in order to capture the role of abstention on minority representativeness. Regardless of the typology of abstention, simulation results show that voter abstention always benefits minorities. 相似文献
146.
147.
Gian Tommaso Viola Michele Bortolotti Alessandro Zazzetta 《Journal of polymer science. Part A, Polymer chemistry》1996,34(1):13-24
UV absorption spectra of thermolyzed polybutadienyl- and polyisoprenyl-lithium reveal a chromophore group previously not recognized for such systems; its absorption band at 271 nm has been assigned to a structure with three conjugated double bonds. A two-step mechanism for the formation of this trienic structure is proposed: an intermolecular metallation of associated living ends is followed by lithium hydride (LiH) elimination. Along thermolysis the presence of a dienic structure was also recognized, the latter arising from intramolecular elimination of LiH. The trienyllithium structure is also considered to be an effective species for the observed molecular weight distribution (MWD) variations. The observed different extent of high molecular weight (HMW) for polyisoprenyl- and polybutadienyl-lithium is explained on the basis of a different stability of the intermediates present along the proposed reaction mechanism. The thermolytic behavior of polystyryllithium does not provide any significant change in MWD: the disappearance of the living chain ends, UV detected, is due to an intramolecular LiH elimination which obeys first-order kinetics. The influence of temperature and of the tetrahydrofuran (THF) level on kinetic rate constants was investigated. © 1996 John Wiley & Sons, Inc. 相似文献
148.
Thaís Silva da Rocha Alessandro de Lima Jurandy do Nascimento Silva Geni Rodrigues Sampaio Rosana Aparecida Manlio Soares Freitas Renan Danielski Adriano Costa de Camargo Fereidoon Shahidi Elizabeth Aparecida Ferraz da Silva Torres 《Molecules (Basel, Switzerland)》2022,27(3)
Jua (juá in Portuguese) is an underexplored fruit from Brazil’s northeast. This fruit is rich in antioxidant substances. However, there is a dearth of information about jua’s bioactive potential. The present study evaluated two extraction methods (continuous agitation and ultrasound-assisted extraction—UAE) and employed three different solvents (water, ethanol, and acetone) to efficiently recover soluble phenolic compounds. Aqueous extracts obtained by UAE showed the highest total phenolic content (TPC) and antiradical activity. Besides being an eco-friendly procedure, extraction and/or solubility in an aqueous medium is also important for food application. Ellagic acids were the predominant phenolics (80%) found in aqueous jua pulp extract obtained by UAE, as determined by HPLC, while its TPC was 405.8 gallic acid equivalent per gram of fruit. This extract also exhibited a higher scavenging activity towards peroxyl radicals when compared to that of several other fruits from the literature, including grape, strawberry, cranberry, and walnuts, which are known references in terms of antioxidants. This is the first report that demonstrates jua pulp’s potential as an alternative source of ellagic acid and other phenolic acids and flavonoids. Therefore, the outcome of this study provides new information that can be useful for functional food and nutraceutical industries. 相似文献
149.
Bramanti E D'Ulivo L Lomonte C Onor M Zamboni R Raspi G D'Ulivo A 《Analytica chimica acta》2006,579(1):38-46
A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO− (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (−20 °C).The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 μg L−1 for H2S, 13.7 μg L−1 for CH3SH, 17.7 μg L−1 for C2H5SH and 21.7 μg L−1 for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 μg L−1. Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071 ± 0.154 μg min−1 of H2S, giving a recovery of 99.8 ± 7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil). 相似文献
150.
Saracino MA Mercolini L Musenga A Bugamelli F Raggi MA 《Journal of separation science》2008,31(10):1851-1859
Three analytical methods have been developed and compared for the quality control of a new formulation (Soymen GN(R) capsules) containing soy extract and melatonin for the treatment of menopausal symptoms. The first method is based on MEKC with diode-array detection, using a mixture of basic carbonate buffer (95%) and methanol (5%), containing 55 mM SDS, as the BGE. The second method is an HPLC method with UV detection at 260 nm. The third method is an HPLC method coupled to amperometric detection which is carried out at an oxidation potential of +0.8 V. In both HPLC systems, the chromatographic separation is obtained on an RP C18 column using a mixture of ACN and an acidic phosphate buffer (25:75 v/v) as the mobile phase. A feasible pretreatment procedure with a methanol/water mixture has been implemented to achieve the quantitative extraction of the main soy isoflavones and of melatonin from the capsules. The results obtained with the three methods are in good agreement with each other and satisfactory in terms of linearity (r(2) >0.9996), precision (RSD <5.4%) and accuracy (recovery >97%). Thus, each of the three analytical methods seems to be suitable for the simultaneous analysis of the main soy isoflavones and melatonin in the new commercial formulation. 相似文献