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81.
Manuel Gacitúa Alexander Carreo Rosaly Morales-Guevara Dayn Pez-Hernndez Jorge I. Martínez-Araya Eyleen Araya Marcelo Preite Carolina Otero María Macarena Rivera-Zaldívar Andrs Silva Juan A. Fuentes 《International journal of molecular sciences》2022,23(5)
Searching for adequate and effective compounds displaying antimicrobial activities, especially against Gram-positive bacteria, is an important research area due to the high hospitalization and mortality rates of these bacterial infections in both the human and veterinary fields. In this work, we explored (E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) benzoic acid (SB-1, harboring an intramolecular hydrogen bond) and (E)-2-((4-nitrobenzilidene)amino)aniline (SB-2), two Schiff bases derivatives. Results demonstrated that SB-1 showed an antibacterial activity determined by the minimal inhibitory concentration (MIC) against Staphylococcus aureus, Enterococcus faecalis, and Bacillus cereus (Gram-positive bacteria involved in human and animal diseases such as skin infections, pneumonia, diarrheal syndrome, and urinary tract infections, among others), which was similar to that shown by the classical antibiotic chloramphenicol. By contrast, this compound showed no effect against Gram-negative bacteria (Klebsiella pneumoniae, Escherichia coli, and Salmonella enterica). Furthermore, we provide a comprehensive physicochemical and theoretical characterization of SB-1 (as well as several analyses for SB-2), including elemental analysis, ESMS, 1H and 13C NMR (assigned by 1D and 2D techniques), DEPT, UV-Vis, FTIR, and cyclic voltammetry. We also performed a computational study through the DFT theory level, including geometry optimization, TD-DFT, NBO, and global and local reactivity analyses. 相似文献
82.
Oscar O. Solis-Castro Marcelo N. Rivolta Fiona M. Boissonade 《International journal of molecular sciences》2022,23(5)
Evidence from dental-related stem cells (DRSCs) suggests an enhanced potential for ectodermal lineage differentiation due to their neural crest origin. Growing evidence that DRSC cultures can produce cells with a neural crest-derived stem cell (NCSC)-like phenotype supports their potential for future therapeutic approaches for neurodegenerative diseases and nerve injuries. However, most of the evidence is limited to the characterization of DRSCs as NCSCs by detecting the expression of neural crest markers. Only a few studies have provided proof of concept of an improved neuro-glial differentiation or direct applicability in relevant models. In addition, a current problem is that several of the existing protocols do not meet manufacturing standards for transferability to a clinical scenario. This review describes the current protocols to obtain NCSCs from DRSCs and their characterization. Also, it provides important considerations from previous work where DRSCs were established and characterized as mesenchymal stromal cells but studied for their neuro-glial differentiation potential. The therapeutic advancement of DRSCs would depend on establishing protocols that can yield a neural crest-like phenotype efficiently, using appropriate manufacturing standards and testing them in relevant models of disease or injury. Achieving these conditions could then facilitate and validate the therapeutic potential of DRSC-NCSCs in regenerative therapies. 相似文献
83.
Marcelo Pereira da Silva Rafael Rodrigues Obelheiro 《International Journal of Parallel, Emergent and Distributed Systems》2017,32(4):348-367
With the ever increasing dependence on computers and networks, many systems are required to be continuously available in order to fulfil their mission. Virtualization technology enables high availability to be offered in a convenient, cost-effective manner: with the encapsulation provided by virtual machines (VMs), entire systems can be replicated transparently in software, obviating the need for expensive fault-tolerant hardware. Remus is a VM replication mechanism for the Xen hypervisor that provides high availability despite crash failures. Replication is performed by checkpointing the VM at fixed intervals. However, there is an antagonism between processing and communication regarding the optimal checkpoint interval: while longer intervals benefit processor-intensive applications, shorter intervals favour network-intensive applications. Thus, any chosen interval may not always be suitable for the hosted applications, limiting Remus usage in many scenarios. This work introduces Adaptive Remus, a proposal for adaptive checkpointing in Remus that dynamically adjusts the replication frequency according to the characteristics of running applications. Experimental results indicate that our proposal improves performance for applications that require both processing and communication, without harming applications that use only one type of resource. 相似文献
84.
Marcelo R. da Silva Luis V. A. Scalvi Luiz H. Dall’Antonia Dayse I. dos Santos 《Journal of Materials Science: Materials in Electronics》2013,24(6):1823-1831
Thin films of the semiconductor NiO are deposited using a straightforward combination of simple and versatile techniques: the co-precipitation in aqueous media along with the dip- coating process. The obtained material is characterized by gravimetric/differential thermal analysis (TG–DTA) and X-ray diffraction technique. TG curve shows 30 % of total mass loss, whereas DTA indicates the formation of the NiO phase about 578 K (305 °C). X-ray diffraction (XRD) data confirms the FCC crystalline phase of NiO, whose crystallinity increases with thermal annealing temperature. UV–Vis optical absorption measurements are carried out for films deposited on quartz substrate in order to avoid the masking of bandgap evaluation by substrate spectra overlapping. The evaluated bandgap is about 3.0 eV. Current–voltage (I–V) curves measured for different temperatures as well as the temperature-dependent resistivity data show typical semiconductor behavior with the resistivity increasing with the decreasing of temperature. The Arrhenius plot reveals a level 233 meV above the conduction band top, which was attributed to Ni2+ vacancy level, responsible for the p-type electrical nature of NiO, even in undoped samples. Light irradiation on the films leads to a remarkable behavior, because above bandgap light induced a resistivity increase, despite the electron–hole generation. This performance was associated with excitation of the Ni2+ vacancy level, due to the proximity between energy levels. 相似文献
85.
Michele A. Salvador Marcelo A. Pereira-da-Silva Antonio J.F. Carvalho 《Polymer》2010,51(18):4145-4151
Highly ordered A-B-A block copolymer arrangements in the submicrometric scale, resulting from dewetting and solvent evaporation of thin films, have inspired a variety of new applications in the nanometric world. Despite the progress observed in the control of such structures, the intricate scientific phenomena related to regular patterns formation are still not completely elucidated. SEBS is a standard example of a triblock copolymer that forms spontaneously impressive pattern arrangements. From macroscopic thin liquid films of SEBS solution, several physical effects and phenomena act synergistically to achieve well-arranged patterns of stripes and/or droplets. That is, concomitant with dewetting, solvent evaporation, and Marangoni effect, Rayleigh instability and phase separation also play important role in the pattern formation. These two last effects are difficult to be followed experimentally in the nanoscale, which render difficulties to the comprehension of the whole phenomenon. In this paper, we use computational methods for image analysis, which provide quantitative morphometric data of the patterns, specifically comprising stripes fragmentation into droplets. With the help of these computational techniques, we developed an explanation for the final part of the pattern formation, i.e. structural dynamics related to the stripes fragmentation. 相似文献
86.
Fabrício A.M. Moura José R. Camacho Marcelo L.R. Chaves Geraldo C. Guimarães 《Electric Power Systems Research》2010
The main task in this paper is to present a performance analysis of a distribution network in the presence of an independent power producer (IP) synchronous generator with its speed governor and voltage regulator modeled using TACS – Transient Analysis of Control Systems, for distributed generation studies. Regulators were implemented through their transfer functions in the S domain. However, since ATP-EMTP (Electromagnetic Transient Program) works in the time domain, a discretization is necessary to return the TACS output to time domain. It must be highlighted that this generator is driven by a steam turbine, and the whole system with regulators and the equivalent of the power authority system at the common coupling point (CCP) are modeled in the “ATP-EMTP – Alternative Transients Program”. 相似文献
87.
Solution annealed and water quenched duplex and super duplex stainless steels are thermodynamically metastable systems at room temperature.These systems do not migrate spontaneously to a thermodynamically stable condition because an energy barrier separates the metastable and stable states. However, any heat input they receive, for example through isothermal treatment or through prolonged exposure to a voltaic arc in the welding process, cause them to reach a condition of stable equilibrium which, for super duplex stainless steels, means precipitation of intermetallic and carbide phases. These phases include the sigma phase, which is easily identified from its morphology, and its influence on the material's impact strength.The purpose of this work was to ascertain how 2-hour isothermal heat treatments at 920 °C and 980 °C affect the microstructure of ASTM A890/A890M GR 6A super duplex stainless steel. The sigma phase morphologies were found to be influenced by these two aging temperatures, with the material showing a predominantly lacy microstructure when heat treated at 920 °C and block-shaped when heat treated at 980 °C. 相似文献
88.
89.
Aline T. PERES Maria A. DALBONI Maria E. CANZIANI Silvia R. MANFREDI Jose Tarcisio G. CARVALHO Marcelo C. BATISTA Lilian CUPPARI Aluisio B. CARVALHO Rosa M. A. MOYSES Nadia GUIMARÃES Vanda JORGETTI Maria C. ANDREOLI Sergio A. DRAIBE Miguel CENDOROGLO 《Hemodialysis international. International Symposium on Home Hemodialysis》2009,13(3):271-277
It has been suggested that phosphate binders may reduce the inflammatory state of hemodialysis (HD) patients. However, it is not clear whether it has any effect on oxidative stress. The objective of this study was to evaluate the effect of sevelamer hydrochloride (SH) and calcium acetate (CA) on oxidative stress and inflammation markers in HD patients. Hemodialysis patients were randomly assigned to therapy with SH (n=17) or CA (n=14) for 1 year. Before the initiation of therapy (baseline) and at 12 months, we measured in vitro reactive oxygen species (ROS) production by stimulated and unstimulated polymorphonuclear neutrophils and serum levels of tumor necrosis factor α, interleukin-10, C-reactive protein, and albumin. There was a significant reduction of spontaneous ROS production in both groups after 12 months of therapy. There was a significant decrease of Staphylococcus aureus stimulated ROS production in the SH group. There was a significant increase in albumin serum levels only in the SH group. In the SH group, there was also a decrease in the serum levels of tumor necrosis factor α and C-reactive protein. Our results suggest that compared with CA treatment, SH may lead to a reduction in oxidative stress and inflammation. Therefore, it is possible that phosphate binders exert pleiotropic effects on oxidative stress and inflammation, which could contribute toward decreasing endothelial injury in patients in HD. 相似文献
90.
João Felipe G. Oliveira Izabelly Larissa Lucena Rosana M. Alves Saboya Marcelo L. Rodrigues Antonio Eurico B. Torres Fabiano A. Narciso Fernandes Célio L. Cavalcante Expedito José S. Parente 《Renewable Energy》2010,35(11):2581-2584
The production of biodiesel by esterification with ethanol using waste oil generated in the refining of coconut oil was investigated in this study. The reaction was performed with and without adsorption of water in order to verify the effect of removing water on the reaction conversion. Methanol was also evaluated as an esterification agent. For both ethanol and methanol, conversions over 99% mol were observed. Simultaneous water adsorption allowed the use of lower alcohol/oil molar ratios thus enabling better economics to a possible industrial process. 相似文献