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Roberto Pestana-Nobles Jorge A. Leyva-Rojas Juvenal Yosa 《Molecules (Basel, Switzerland)》2020,25(22)
Biofilms are communities of microorganisms that can colonize biotic and abiotic surfaces and thus play a significant role in the persistence of bacterial infection and resistance to antimicrobial. About 65% and 80% of microbial and chronic infections are associated with biofilm formation, respectively. The increase in infections by multi-resistant bacteria instigates the need for the discovery of novel natural-based drugs that act as inhibitory molecules. The inhibition of diguanylate cyclases (DGCs), the enzyme implicated in the synthesis of the second messenger, cyclic diguanylate (c-di-GMP), involved in the biofilm formation, represents a potential approach for preventing the biofilm development. It has been extensively studied using PleD protein as a model of DGC for in silico studies as virtual screening and as a model for in vitro studies in biofilms formation. This study aimed to search for natural products capable of inhibiting the Caulobacter crescentus enzyme PleD. For this purpose, 224,205 molecules from the natural products ZINC15 database, have been evaluated through molecular docking and molecular dynamic simulation. Our results suggest trans-Aconitic acid (TAA) as a possible starting point for hit-to-lead methodologies to obtain new inhibitors of the PleD protein and hence blocking the biofilm formation. 相似文献
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One of the important reactive steps in Earth's atmosphere is the decomposition of H(2)SO(4) to H(2)O and SO(3). However, because the UV spectrum of H(2)SO(4) was not found up to 140 nm, alternative mechanisms, including vibrationally induced dissociation, were proposed. Using adiabatic reactive molecular dynamics (ARMD) simulations with validated force fields for the product and educt channels, it is shown through explicit atomistic simulation that by exciting the ν(9) (OH-stretching-) mode, photodissociation can occur on the picosecond time scale. With the potential energy surfaces used in the present work, ν(9) = 4 is sufficient for this process. From a statistically significant number of trajectories (several thousands), vibrationally induced dissociation times are found to follow Gamma-distributions with most likely reaction times between 40 and 200 ps by depositing energies ranging from 40 to 60 kcal/mol, corresponding to 4 and 6 vibrational quanta in the OH stretching vibration. Because ARMD simulations allow multiple and long-time simulations, both nonstatistical, impulsive H-transfer and statistical, IVR-regimes of the decomposition reaction can be discussed in detail at an atomistic level. 相似文献
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de Oliveira Edilene Gadelha de Caland Lília Basílio de Oliveira Alice Rodrigues Machado Paula Renata Lima Farias Kleber Juvenal Silva da Costa Tiago R. Melo Dulce Maria Araujo Cornélio Alianda Maira Fernandes-Pedrosa Matheus de Freitas da Silva-Júnior Arnóbio Antônio 《Journal of Thermal Analysis and Calorimetry》2017,129(3):1481-1494
Boron phosphates (BPs) with different acidities were prepared by regulating the calcination temperatures for the reaction products of boric acid and phosphoric acid. The crystal structure, morphology, surface acidity, and thermal stability were characterized by X-ray diffraction, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), chemical absorbed apparatus, and thermogravimetric analysis (TG). The effects of BPs on the combustion behavior and catalyzing the carbonization of bisphenol-A epoxy resin (EP) were investigated by the limiting oxygen index (LOI) and cone calorimetry test. Upon loading 5 mass% BP prepared at 300 °C, the LOI value of the EP/BP composites increased to 29.6%, and moreover, the peak heat release rate and average specific extinction area decreased by 43 and 25%, respectively. A possible catalyzing carbonization mechanism was explored by TG coupled with Fourier transform infrared spectroscopy (TG–FTIR), TG, FTIR, SEM, Raman spectroscopy (Raman), and XPS. The results demonstrated that BP catalyzed EP to degrade at relatively low temperature, and the yield, compactness, and graphitization degree of the char residue were obviously enhanced with an increase in the ratio of Brønsted and Lewis acid sites (B/L value) and the total surface acid sites on the BP surface. Therefore, the catalyzing carbonization flame retardancy of the EP/BP composites can be improved through regulating the surface acidity of BP. 相似文献
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Juan Luis Manríquez Zepeda Juvenal Rueda Paz Manuel Avila Aoki Shi-Hai Dong 《Entropy (Basel, Switzerland)》2022,24(6)
We study both pentapartite GHZ and W-class states in the noninertial frame and explore their entanglement properties by carrying out the negativities including 1-4, 2-3, and 1-1 tangles, the whole entanglement measures such as algebraic and geometric averages and , and von Neumann entropy. We illustrate graphically the difference between the pentapartite GHZ and W-class states. We find that all 1-4, 2-3 tangles and the whole entanglements, which are observer dependent, degrade more quickly as the number of accelerated qubits increases. The entanglements of these quantities still exist even at the infinite acceleration limit. We also notice that all 1-1 tangles of pentapartite GHZ state where , whereas all 1-1 tangles of the W-class state and are unequal to zero, e.g., but and disappear at and , respectively. We notice that the entanglement of the pentapartite GHZ and W-class quantum systems decays faster as the number of accelerated particles increases. Moreover, we also illustrate the difference of von Neumann entropy between them and find that the entropy in the pentapartite W-class state is greater than that of GHZ state. The von Neumann entropy in the pentapartite case is more unstable than those of tripartite and tetrapartite subsystems in the noninertial frame. 相似文献
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Lalli PM Iglesias BA Toma HE de Sa GF Daroda RJ Silva Filho JC Szulejko JE Araki K Eberlin MN 《Journal of mass spectrometry : JMS》2012,47(6):712-719
Travelling wave ion mobility mass spectrometry (TWIM-MS) with post-TWIM and pre-TWIM collision-induced dissociation (CID) experiments were used to form, separate and characterize protomers sampled directly from solutions or generated in the gas phase via CID. When in solution equilibria, these species were transferred to the gas phase via electrospray ionization, and then separated by TWIM-MS. CID performed after TWIM separation (post-TWIM) allowed the characterization of both protomers via structurally diagnostic fragments. Protonated aniline (1) sampled from solution was found to be constituted of a ca. 5:1 mixture of two gaseous protomers, that is, the N-protonated (1a) and ring protonated (1b) molecules, respectively. When dissociated, 1a nearly exclusively loses NH(3) , whereas 1b displays a much diverse set of fragments. When formed via CID, varying populations of 1a and 1b were detected. Two co-existing protomers of two isomeric porphyrins were also separated and characterized via post-TWIM CID. A deprotonated porphyrin sampled from a basic methanolic solution was found to be constituted predominantly of the protomer arising from deprotonation at the carboxyl group, which dissociates promptly by CO(2) loss, but a CID-resistant protomer arising from deprotonation at a porphyrinic ring NH was also detected and characterized. The doubly deprotonated porphyrin was found to be constituted predominantly of a single protomer arising from deprotonation of two carboxyl groups. 相似文献
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Mbakop T. Tchakouteu Deutou Juvenal G. Nemaleu Boubakar Likiby Billong Ndigui Melo U. Chinje Kamseu Elie Sglavo Vincenzo M. 《Journal of Thermal Analysis and Calorimetry》2021,144(1):91-106
Journal of Thermal Analysis and Calorimetry - Limestone was used to modify the fluxing action of two potash feldspars (a pure potash feldspar and a soda-potash feldspar) labeled P and C,... 相似文献
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Priscila M. Lalli Bernardo A. Iglesias Henrique E. Toma Gilberto F. de Sa Romeu J. Daroda Juvenal C. Silva Filho Jan E. Szulejko Koiti Araki Marcos N. Eberlin 《Journal of mass spectrometry : JMS》2012,47(6):712-719
Travelling wave ion mobility mass spectrometry (TWIM‐MS) with post‐TWIM and pre‐TWIM collision‐induced dissociation (CID) experiments were used to form, separate and characterize protomers sampled directly from solutions or generated in the gas phase via CID. When in solution equilibria, these species were transferred to the gas phase via electrospray ionization, and then separated by TWIM‐MS. CID performed after TWIM separation (post‐TWIM) allowed the characterization of both protomers via structurally diagnostic fragments. Protonated aniline (1) sampled from solution was found to be constituted of a ca. 5:1 mixture of two gaseous protomers, that is, the N‐protonated (1a) and ring protonated (1b) molecules, respectively. When dissociated, 1a nearly exclusively loses NH3, whereas 1b displays a much diverse set of fragments. When formed via CID, varying populations of 1a and 1b were detected. Two co‐existing protomers of two isomeric porphyrins were also separated and characterized via post‐TWIM CID. A deprotonated porphyrin sampled from a basic methanolic solution was found to be constituted predominantly of the protomer arising from deprotonation at the carboxyl group, which dissociates promptly by CO2 loss, but a CID‐resistant protomer arising from deprotonation at a porphyrinic ring NH was also detected and characterized. The doubly deprotonated porphyrin was found to be constituted predominantly of a single protomer arising from deprotonation of two carboxyl groups. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Aluminum and silicon have been observed to be present in the human degenerated brain and normal elderly brains by using a combination of scanning electron microscopy and X-ray spectrometry (EDS-SEM). Al and Si of electric organs were also reported - in electrocytes and cholinergic nerves - from living electric fish (family Rajidae). A biogenically produced crystalline mineral phase (i.e., chalcedony) has also been observed in electric organs by using a mineralogical microscope. Based on this evidence we decided to explore the presence of chalcedony (SiO(2)) in the human central nervous system (CNS). Sections from aged patients (mean, 81 years) were collected after autopsy and observed using a Leica DMLP mineralogical microscope. Chalcedony was detected in cerebral cortex and cerebellum. In plane-polarized light, chalcedony is rounded in shape, 12-20mum in size, translucent, with a low refraction index. The crossed-polarizer image shows first order birefringence color (grey-white) and radial extinction. Chalcedony was also detected in the hippocampus in large amounts and sizes (50-60mum). Chalcedony is a microcrystalline fibrous form of silica. It consists of nanoscale intergrowths of quartz and the optically length-slow fibrous silica polymorph moganite. Chalcedony precipitation occurs at a specific pH (7-8) and oxidation potential (Eh; 0.0 to -0.2) in geological environments. This observation supports the important role played by pH and Eh conditions in silica precipitation in elderly brains, as has also been reported in peripheral cholinergic nerves in electric organ from living electric fish. Carbonic anhydrases (CAs) (silicase) are involved in physiological pH regulation and may also be participating in the polymerization-depolymerization of chalcedony in the human brain. This is the first time a biogenically produced crystalline mineral phase (i.e., chalcedony) has been observed in the human CNS from aged patients. 相似文献
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