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排序方式: 共有248条查询结果,搜索用时 250 毫秒
81.
82.
Valquíria Campos Alencar Juliana de Ftima dos Santos Silva Renata Ozelami Vilas Boas Vinícius Manganaro Farnzio Yara N. L. F. de Maria David Aciole Barbosa Alex Tramontin Almeida Emanuel Maltempi de Souza Marcelo Müller-Santos Daniela L. Jabes Fabiano B. Menegidio Regina Costa de Oliveira Tiago Rodrigues Ivarne Luis dos Santos Tersariol Adrian R. Walmsley Luiz R. Nunes 《International journal of molecular sciences》2021,22(11)
Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N2 fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N2 fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants. 相似文献
83.
Leonardo D. Apolinário Emerson Colonetti Rodrigo Cercená Fabiano da Silveira Santos Maykon Cargnin Alexandre G. Dal-Bó 《应用聚合物科学杂志》2020,137(41):49237
The properties of flexographic inks obtained by the partial replacement of nitrocellulose (NC) resin with different amounts of polyurethane (PU) resins were evaluated for the statistical planning of mixtures to develop an optimum ink formulation. The formulations were developed using a statistical tool and they were found to present properties predicted by the tool. The results indicate that the substitution of the NC resin with PU resins leads to increased resistance of the ink film to delamination. The system obtained with the partial substitution of NC with PU has higher lamination bond strength than the pure NC-based system. The ink films of the formulations NC-based and NC/PU-based were evaluated by spectroscopy UV–vis, both inks have similar transparency of greater than 95% above 575 nm. When exposed to water, milk, and UV light, ink surfaces showed similar behavior in the atomic force microscope, Fourier-transform infrared spectroscopy, and UV–vis analysis. However, ink formulations with higher PU contents underwent higher photodegradation. Other properties such as the viscosity ink, gloss, coating strength, color, adhesion, and blocking of the NC/PU-based ink film did not vary significantly when compared to those of the standard ink produced exclusively with NC resin. 相似文献
84.
Márcio José dos Reis Vanessa Prévot Fabrice Leroux Fabiano Silvério João Barros Valim 《Journal of Porous Materials》2010,17(4):443-451
New organic/inorganic (O/I) hybrid assemblies based on Layered Double Hydroxide (LDH) with polyamide amine dendrimer (PAMAM,
generation −0.5 and generation +0.5) were prepared by two different routes using either the direct coprecipitation at constant
pH or the anion exchange procedure in double surfactant S+S− phases. The obtained materials were characterized by means of powder X-ray diffraction, thermal gravimetric analysis associated
with mass spectrometry, and Fourier-transform infrared spectroscopy. X-ray powder diffraction pattern of the O/I LDH assembly
exhibit characteristic profiles of LDH-based materials with basal spacing depending on the nature of the dendrimer. Indeed,
for both synthetic procedures, interleaved PAMAM −0.5 gives rise to an interlayer space in agreement with a perpendicular
molecular arrangement against the layer of the host structure. For PAMAM+0.5, considering its spherical dimension, a much
smaller basal spacing was observed. This observation was interpreted as shrinkage of the molecule to accommodate the interlayer
LDH gap, which was rendered possible by the bond angle twisting within PAMAM−0.5. FTIR spectra confirm the presence of both
moieties inside both Zn2Al/PAMAM G−0.5 and Zn2Al/PAMAM G+0.5 assemblies. Finally, thermal analysis associated with mass spectrometry confirm this composition, and in situ
temperature XRD data reveal that the highly constrained arrangement for the generation +0.5 is not accompanied by a gain in
thermal structural stability; in fact, the assembly prepared from PAMAM −0.5 is more stable. Both O/I PAMAM LDH assemblies
constitute well-defined materials which are candidate for catalytic applications. 相似文献
85.
Sueli Rodrigues Maria CF Gomes Maria I Gallo Fabiano AN Fernandes 《Journal of the science of food and agriculture》2009,89(4):665-670
BACKGROUND: Drying is a traditional way of fruit preservation. Because of the high energy costs associated with air‐drying, osmotic dehydration is often applied as a pretreatment to reduce air‐drying time. Ultrasound is an emerging technology with several applications in food processing. The effect of ultrasound on fruit tissue depends on the tissue structure and composition, and ultrasound might be beneficial to improve air‐drying efficiency, with consequent reduction in process costs. In this study the effect of ultrasound and ultrasound‐assisted osmotic dehydration on sapota tissue structure was evaluated. RESULTS: Ultrasound induced cell disruption and breakdown of cells with high phenolic content (dense cells) and also induced elongation of parenchyma cells. Ultrasound application combined with high osmotic gradient enhanced water loss and solid gain because of the formation of microscopic channels. Ultrasound‐assisted osmotic dehydration induced gradual distortion of the shape of cells, cell breakdown and formation of microscopic channels. Micrographs of the fruit tissue showed that ultrasound preferentially affected dense cells. CONCLUSION: Ultrasonic pretreatment was able to preserve the tissue structure of the fruit when distilled water was used as liquid medium. The application of ultrasound‐assisted osmotic dehydration resulted in severe changes in the tissue structure of the fruit, with consequent increase in the effective water diffusivity, because of the formation of microscopic channels and cell rupture. Copyright © 2009 Society of Chemical Industry 相似文献
86.
Matteo Bordiga Gianluca Piana Jean Daniel Coïsson Fabiano Travaglia Marco Arlorio 《International Journal of Food Science & Technology》2014,49(3):787-796
This study presents the application of a headspace solid‐phase microextraction (HS‐SPME) method on the analysis of Nebbiolo‐based wine volatiles by comprehensive two‐dimensional gas chromatography (GC×GC) and time‐of‐flight mass spectrometry (TOF‐MS). The aroma patterns were established for different samples of Nebbiolo‐based wines, aged in oak wood barrels for 18 months at constant temperature. The methodology allowed for the simultaneous analysis of over 130 different volatile compounds detected in the headspace. The odour activity values (OAVs) were assessed to identify potentially important odorants of Nebbiolo‐based wine during ageing. The highest OAVs were obtained for several compounds such as ethyl octanoate, ethyl hexanoate, isoamyl acetate, β‐damascenone, ethyl cinnamate, ethyl 3‐methylbutanate and acetaldehyde. Ethyl butanoate, octanoic acid, ethyl dihydrocinnamate and γ‐nonalactone were also at concentrations higher than their corresponding threshold. Also vanillin, (E)‐whisky lactone, (Z)‐whisky lactone, guaiacol and 4‐ethyl guaiacol seem to be important odorants after oak wood ageing period. 相似文献
87.
Evaluation of plasma,high‐pressure and ultrasound processing on the stability of fructooligosaccharides
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Elenilson G. Alves Filho Patrick J. Cullen Jesus M. Frias Paula Bourke Brijesh K. Tiwari Edy S. Brito Sueli Rodrigues Fabiano A.N. Fernandes 《International Journal of Food Science & Technology》2016,51(9):2034-2040
Fructooligosaccharides (FOS) are among the main carbohydrates with prebiotic activity, and they are the most applied functional carbohydrate ingredient in the food industry. FOS are known to hydrolyse when subjected to thermal processing, thus partially losing its functional properties. In this study, we evaluate whether three nonthermal technologies are suitable for processing FOS regarding its stability after processing. FOS were subjected to ultrasound, high‐pressure processing (HPP) and atmospheric cold plasma (ACP). The FOS solution, 70 g L?1, was set at a concentration recommended for human intake. The treatments were carried out at operating conditions usually used for microbial inactivation in foods (HPP at 450 MPa for 5 min; US at 600–1200 W L?1 for 5 min; ACP at 70 kV for 15–60 s). NMR and HPLC analysis of the FOS components showed that ACP, ultrasound and HPP have not induced any significant change on FOS concentration (<2.0%) nor on the degree of polymerisation of the FOS (<3.3%). Contrarily to what is reported for thermal treatments, these nonthermal technologies were considered suitable for FOS processing. 相似文献
88.
1H‐NMR and isotopic fingerprinting of olive oil and its unsaponifiable fraction: Geographical origin of virgin olive oils by pattern recognition
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89.
Ulisses M. Teles Fabiano A. N. Fernandes Sueli Rodrigues réa S. Lima Geraldo A. Maia & Raimundo W. Figueiredo 《International Journal of Food Science & Technology》2006,41(6):674-680
Osmotic dehydration represents a technological alternative to reduce post‐harvest losses of fruits. In this work, the influence of the osmotic solution concentration and osmotic solution to fruit weight ratio was examined on the osmotic dehydration of melons under vacuum. The process of osmotic dehydration followed by air‐drying was studied and modelled so that it could be optimised. The developed model has been validated with experimental data and simulations have shown that how the operating conditions affect the process. An optimisation was done using the model in order to search for the best operating condition that would reduce the total processing time. 相似文献
90.
Polymorphism in Crystalline Microfibers of Achiral Octithiophene: The Effect on Charge Transport,Supramolecular Chirality and Optical Properties
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Francesca Di Maria Eduardo Fabiano Denis Gentili Mariano Biasiucci Tommaso Salzillo Giacomo Bergamini Massimo Gazzano Alberto Zanelli Aldo Brillante Massimiliano Cavallini Fabio Della Sala Giuseppe Gigli Giovanna Barbarella 《Advanced functional materials》2014,24(31):4943-4951
Polymorphic crystalline microfibers from an achiral octithiophene with one S‐hexyl substituent per ring are separately and reproducibly grown with the same characteristics on various solid surfaces, including the interdigitated electrodes/SiO2 surface of a bottomcontact field‐effect transistor. The arrangement of the same molecule in two diverse supramolecular structures leads to markedly different electronic, optical, and charge mobility properties. The microfibers—straight and yellow emitting or helical and red emitting—exhibit p‐type charge transport characteristics, with the yellow ones showing a charge mobility and on/off current ratio of one and three orders of magnitude, respectively, greater than the red ones. Both forms show circular dichroism signals with significant differences from one form to the other. DFT calculations show that the octithiophene exists in two different quasi‐equienergetic conformations aggregating with diverse orientations of the substituents. This result suggests that the observed polymorphism is conformational in nature. The self‐assembly, driven by sulfur–sulfur non‐bonding interactions, amplifies the small property differences between conformers, leading to quite different bulk properties. 相似文献