Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be...Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be an interesting alternative to post infection allopathic treatment with antibiotics. Lactococcus lactis is one of the most important bacteria used in dairy technology. In this work, a total of 21 Lactococcus lactis subsp. Lactis strains, 20 from goat milk whey and one strain from cow milk were used to evaluate their antibacterial activity against four pathogenic germs responsible for mastitis: Escherichia coli, Staphylococcus aureus, Streptococcus uberis and Streptococcus agalactiae. The nisin-producing cow milk strain was active against St. uberis and Str. Agalactiae using the well diffusion method. For the strains isolated from goat milk whey, no antimicrobial effect was observed against these pathogens. However, a different approach based on the growth of pathogenic bacteria interacting with the Lactococcus lactis strains in a minimum medium was used to study the barrier effect of LAB. The Lactococcus lactis strains S1 and S2 from goat milk whey depleted the growth of Sa. aureus, St. uberis and E. coli during 8 h and stopped the development of St. agalactiae.展开更多
Entropy generation minimization for heat and mass transfer process in a solid-gas reactor is carried out based on constructal theory by using triangular elemental area. The aspect ratio of the triangular elemental are...Entropy generation minimization for heat and mass transfer process in a solid-gas reactor is carried out based on constructal theory by using triangular elemental area. The aspect ratio of the triangular elemental area is optimized under constraint conditions. A number of optimal triangular elements are assembled to a new large rectangular area, which is optimised again. The procedure is repeated until the control-volume is covered, and the complete analytical results are obtained. The effects of some parameters on minimum entropy generation are analysed by nu-merical examples. The results show that smaller entropy generation can be ob-tained when the optimization for a given volume is carried out on the basis of tri-angular elements than those obtained on the basis of rectangular elements.展开更多
By exploiting the combined use of a heterogeneous recyclable palladium(II)-bis(N-heterocyclic carbene)catalyst and cyclopentyl methyl ether(CPME)as a convenient recoverable safer reaction medium,an effective wastemini...By exploiting the combined use of a heterogeneous recyclable palladium(II)-bis(N-heterocyclic carbene)catalyst and cyclopentyl methyl ether(CPME)as a convenient recoverable safer reaction medium,an effective wasteminimized approach has been developed for the intramolecular Pd-catalyzed C(sp3)-H activation of methyl pyrrole derivatives.This synthetic tools has allowed to access condensed N-heterocycles generally endowed with biological activities and representatively are the core motif of complex molecules such as Mitomycines and Tylophorines.The heterogeneous catalytic system could be recovered and reused up to representative five runs without any loss in efficiency.The target products(19 examples)have been obtained selectively and with excellent isolated yields up to 93%.The approach leads to the definition of a protocol with a very good E-factor(21)which is much lower(up to 98%)than those of comparable literature examples.Other green metrics have been calculated and the data collected demonstrate that our newly developed protocol is very promising in terms of its environmental impact profile.展开更多
文摘Bovine mastitis affects the udder health and thus causing significant economic losses. Probiotic products based on the use of lactic acid bacteria (LAB) to limit pathogens multiplication and pre-infection risks can be an interesting alternative to post infection allopathic treatment with antibiotics. Lactococcus lactis is one of the most important bacteria used in dairy technology. In this work, a total of 21 Lactococcus lactis subsp. Lactis strains, 20 from goat milk whey and one strain from cow milk were used to evaluate their antibacterial activity against four pathogenic germs responsible for mastitis: Escherichia coli, Staphylococcus aureus, Streptococcus uberis and Streptococcus agalactiae. The nisin-producing cow milk strain was active against St. uberis and Str. Agalactiae using the well diffusion method. For the strains isolated from goat milk whey, no antimicrobial effect was observed against these pathogens. However, a different approach based on the growth of pathogenic bacteria interacting with the Lactococcus lactis strains in a minimum medium was used to study the barrier effect of LAB. The Lactococcus lactis strains S1 and S2 from goat milk whey depleted the growth of Sa. aureus, St. uberis and E. coli during 8 h and stopped the development of St. agalactiae.
基金the Program for New Century Excellent Talents in Universities of China (Grant No. NCET-04-1006)Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 200136)
文摘Entropy generation minimization for heat and mass transfer process in a solid-gas reactor is carried out based on constructal theory by using triangular elemental area. The aspect ratio of the triangular elemental area is optimized under constraint conditions. A number of optimal triangular elements are assembled to a new large rectangular area, which is optimised again. The procedure is repeated until the control-volume is covered, and the complete analytical results are obtained. The effects of some parameters on minimum entropy generation are analysed by nu-merical examples. The results show that smaller entropy generation can be ob-tained when the optimization for a given volume is carried out on the basis of tri-angular elements than those obtained on the basis of rectangular elements.
基金funded by the European Union-NextGenerationEU under the Italian Ministry of University and Research(MUR)National Innovation Ecosystem grant ECS00000041-VITALITY.
文摘By exploiting the combined use of a heterogeneous recyclable palladium(II)-bis(N-heterocyclic carbene)catalyst and cyclopentyl methyl ether(CPME)as a convenient recoverable safer reaction medium,an effective wasteminimized approach has been developed for the intramolecular Pd-catalyzed C(sp3)-H activation of methyl pyrrole derivatives.This synthetic tools has allowed to access condensed N-heterocycles generally endowed with biological activities and representatively are the core motif of complex molecules such as Mitomycines and Tylophorines.The heterogeneous catalytic system could be recovered and reused up to representative five runs without any loss in efficiency.The target products(19 examples)have been obtained selectively and with excellent isolated yields up to 93%.The approach leads to the definition of a protocol with a very good E-factor(21)which is much lower(up to 98%)than those of comparable literature examples.Other green metrics have been calculated and the data collected demonstrate that our newly developed protocol is very promising in terms of its environmental impact profile.
