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121.
Juliana M. OliveiraJuliano C. R. Freitas João Valdir ComassetoPaulo Henrique Menezes 《Tetrahedron》2011,67(16):3003-3009
A new approach for the synthesis of α,β-unsaturated δ-lactones, a unit present in many natural products with interesting biological activities is described. The approach was based on the use of a vinyl telluride, and it is complementary to the methods using ring-closing metathesis. The sequence was performed in good overall yield with retention of the Z-double bond geometry. 相似文献
122.
Marcela Araugio Soares Juliana Lage Mattos Priscila Brunelli Pujatti Alexandre Soares Leal Wagner Gouvêa dos Santos Raquel Gouvêa dos Santos 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):61-65
The proposal of this work was to investigate the effect of the radioactive (NH3)2PtCl2, cis-diamminedichloroplatinum (II) or CDDP* on malignant glioma cells and verify if the low-dose continuous internal radio-chemotherapy
would be able to produce additive effects. The antitumoral activity of CDDP* and the non labeled cisplatin, CDDP, were evaluated
in glioblastoma. Cisplatin was cytotoxic for glioblastoma cells in a dose dependent manner. Treatment with CDDP*, (IC50 = 1.75 ± 0.07 μM), proved to be more potent than using just CDDP, (IC50 = 4.96 ± 0.40 μM). These results suggest that cisplatin is a very potent radiosensitizer evoking a supra additive effect.
Internal radio-chemotherapy treatment based on CDDP* may be useful alternative to reduce the drug concentration required for
effective inhibition of glioblastoma growth. 相似文献
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125.
Anderson Hoff Juliana V. dos Santos Cesar Manchein Holokx A. Albuquerque 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(7):1-9
The behavior of neurons can be modeled by the FitzHugh-Nagumo oscillator model, consisting of two nonlinear differential equations, which simulates the behavior of nerve impulse conduction through the neuronal membrane. In this work, we numerically study the dynamical behavior of two coupled FitzHugh-Nagumo oscillators. We consider unidirectional and bidirectional couplings, for which Lyapunov and isoperiodic diagrams were constructed calculating the Lyapunov exponents and the number of the local maxima of a variable in one period interval of the time-series, respectively. By numerical continuation method the bifurcation curves are also obtained for both couplings. The dynamics of the networks here investigated are presented in terms of the variation between the coupling strength of the oscillators and other parameters of the system. For the network of two oscillators unidirectionally coupled, the results show the existence of Arnold tongues, self-organized sequentially in a branch of a Stern-Brocot tree and by the bifurcation curves it became evident the connection between these Arnold tongues with other periodic structures in Lyapunov diagrams. That system also presents multistability shown in the planes of the basin of attractions. 相似文献
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127.
Different analytical methods were optimized and applied to quantify certain surrogate contaminants (toluene, chlorobenzene, phenol, limonene and benzophenone) in samples of contaminated and recycled flakes and virgin pellets of polyethylene terephthalate (PET) coming from the industrial challenge test. A screening analysis of the PET samples was carried out by direct solid-phase microextraction (SPME) in headspace mode (HS). The methods developed and used for quantitative analysis were a) total dissolution of PET samples in dichloroacetic acid and analysis by HS-SPME coupled to gas chromatography–mass spectrometry (GC–MS) and, b) dichloromethane extraction and analysis by GC–MS. The concentration of all surrogates in the contaminated PET flakes analyzed by HS-SPME method was lower than expected according to information provided by the supplier. Dichloroacetic acid interacted with the surrogates, resulting in a tremendous decrease of limonene concentration. The degradation compounds from limonene were identified. Dichloromethane extraction and GC–MS analysis evidenced the highest values of analytes in these PET samples. Based on the foregoing data, the efficiency of the recycling process was evaluated, whereby the removal of 99.9% of the surrogates proceeding from the contaminated flakes was confirmed. 相似文献
128.
Dr. Juliana Martins de Souza e Silva Murilo Pastorello Dr. Jörg Kobarg Dr. Mateus Borba Cardoso Prof. Italo Odone Mazali 《Chemphyschem》2013,14(18):4075-4083
Silver‐based nanocomposites are known to act as biocides against a series of microorganisms and are largely studied as an alternative to substitute conventional antibiotics that show decreasing efficacy. In this work, an eco‐friendly method to synthesize silver nanoparticles assembled on the surface of hexaniobate crystals is reported. By means of ion exchange, K+ ions of layered potassium hexaniobate were partially substituted by Ag+ ions and the resulting material was exposed to UV light. The irradiation allowed the reduction of silver ions with consequent formation of silver nanoparticles located only on the hexaniobate surface, whereas Ag+ ions located in the interlayer space remained in the ionic form. Increasing UV‐light exposure times allowed controlling of the silver nanoparticle size. The antibacterial effects of the pristine potassium hexaniobate and of silver‐containing hexaniobate samples were tested against Escherichia coli (E. coli). The antibacterial efficacy was determined to be related to the presence of silver in hexaniobate. An increasing activity against E. coli was observed with the decrease in silver nanoparticles size, suggesting that silver nanoparticles of distinct sizes interact differently with bacterial cell walls. 相似文献
129.
Alex F. C. Flores Luciana A. Piovesan Lucas Pizzuti Darlene C. Flores Juliana L. Malavolta Marcos A. P. Martins 《Journal of heterocyclic chemistry》2014,51(3):733-740
Efficient heterocyclization of methyl 7,7,7‐trifluoro‐4‐methoxy‐6‐oxo‐4‐heptenoate and methyl 7,7,7‐trichloro‐4‐methoxy‐6‐oxo‐4‐heptenoate into isoxazole and pyrazole derivatives that represent a new type of glutamate‐like 3‐(trihalomethylated‐1,2‐azol‐3‐yl)propanoate is reported. Preparation of the key methyl 7,7,7‐trihalo‐4‐methoxy‐6‐oxohept‐4‐enoate precursors from levulinic acid is also described. The synthetic potential of this synthetic protocol was indicated by the production of several methyl and ethyl 3‐(isoxazol‐3‐yl)propanoates and 3‐(1H‐pyrazol‐3‐yl)propanoates, and the respective acid derivatives, in good (70–95%) yields. The crystal structure for ethyl 5‐(3‐ethoxy‐3‐oxopropyl)‐1H‐pyrazole‐3‐carboxylate ( 10c ) has been determined by monocrystal X‐ray diffraction analysis. The N–H…H intermolecular hydrogen bonds join the molecules into catamer. 相似文献
130.
David L. Mobley Karisa L. Wymer Nathan M. Lim J. Peter Guthrie 《Journal of computer-aided molecular design》2014,28(3):135-150
Here, we give an overview of the small molecule hydration portion of the SAMPL4 challenge, which focused on predicting hydration free energies for a series of 47 small molecules. These gas-to-water transfer free energies have in the past proven a valuable test of a variety of computational methods and force fields. Here, in contrast to some previous SAMPL challenges, we find a relatively wide range of methods perform quite well on this test set, with RMS errors in the 1.2 kcal/mol range for several of the best performing methods. Top-performers included a quantum mechanical approach with continuum solvent models and functional group corrections, alchemical molecular dynamics simulations with a classical all-atom force field, and a single-conformation Poisson–Boltzmann approach. While 1.2 kcal/mol is still a significant error, experimental hydration free energies covered a range of nearly 20 kcal/mol, so methods typically showed substantial predictive power. Here, a substantial new focus was on evaluation of error estimates, as predicting when a computational prediction is reliable versus unreliable has considerable practical value. We found, however, that in many cases errors are substantially underestimated, and that typically little effort has been invested in estimating likely error. We believe this is an important area for further research. 相似文献