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361.
Gastão de Almeida Braga 《Journal of statistical physics》1991,63(1-2):285-289
In this paper we show how to improve the recent result
c
17.2 on the inverse critical temperature for the two-dimensional Coulomb gas at low density to get the following upper bound:
c
16. 相似文献
362.
Walysson Ferreira de Paiva Ingredy Bastos Braga João Vitor de Assis Sandra Milena Bonilla Castañeda Ángel Gabriel Sathicq Valeria Palermo Gustavo Pablo Romanelli Ricardo Natalino Marcio José da Silva Felipe Terra Martins Gustavo Senra Gonçalves de Carvalho Giovanni Wilson Amarante Sergio Antonio Fernandes 《Tetrahedron》2019,75(27):3740-3750
The application of immobilizing calixarene onto the surface of silica using a sol-gel method, as an efficient heterogeneous catalyst (CX4SO3HSi(n)) for multicomponent Povarov reaction has been described. Catalytic activity of the CX4SO3HSi(n) for the synthesis of julolidines under greener and environmentally benign conditions in simple and efficient method was explored. Notably, only 0.5 mol% of the catalyst is sufficient to catalyze the Povarov solvent-free reaction under microwave-assistance. Besides, this protocol allows the construction of four new C–C bonds and two C–N bonds in a single step. To the best of our knowledge, this consists the first silica support calix[4]arene as a heterogeneous catalyst for multicomponent synthesis of julolidines. 相似文献
363.
Isadora Caruso Fontana Oliveira Adriana Dalla Mora Jairo Braga Neto Ákila Lara de Oliveira Carolina Harder Valquíria Miwa Hanai-Yoshida 《Natural product research》2019,33(16):2417-2421
Bothrops jararacussu venom’s (Bj2015) batch was biomonitored quarterly for one year to assess phospholipase A2 (PLA2) activity, immunogenicity, neurotoxicity, and myotoxicity. In silico models were applied to evaluate losses using decay model and recoveries by predictive trend analysis. Mice were immunized with Bj2015. Antibodies were detected by double-immunodiffusion and total protein and albumin were measured. Neuromuscular blockade-induced by 40 μg mL?1 venom solution was carried out using mouse nerve phrenic-diaphragm preparation. Resulting muscles were submitted to light microscopy to evaluate the myotoxicity. PLA2 activity of 0.1 mg mL?1 Bj2015 was measured using 4-nitro-3-(octanoyloxy)benzoic acid as substrate. Over time, greater losses occurred in neurotoxicity than PLA2, but not in myotoxicity and immunogenicity. Concluding, the neurotoxicity decrease can be related to enzymatic losses, including PLA2. Depending on the purpose of use, the collected venom responds on a long time, avoiding unnecessary new collections, improving life quality of animals in captivity and increasing their longevity. 相似文献
364.
Ana Maria Braga de Souza Daniela Kárin Fogliato Jacqueline Marques Petroni Valdir Souza Ferreira 《International journal of environmental analytical chemistry》2019,99(5):397-408
Here we describe the investigation of the electrochemical behaviour and the electroanalytical quantification of hormonal contraceptive levonorgestrel using solid amalgam electrode fabricated with silver nanoparticles. Until now, to the best of our knowledge, this is the first report of the use of solid working electrodes for levonorgestrel determination. Over this electrodic surface, the substance showed one cathodic peak at Ep = ?1.41 V. Moreover, the electrochemical reduction of levonorgestrel was defined as an irreversible and mainly adsorption-controlled process involving two protons and two electrons. Square-wave adsorptive stripping voltammetry (SWAdSV) was used for the quantification of levonorgestrel. The instrumental and experimental parameters were studied and optimized. The best conditions of analysis were observed when using 0.04 mol L?1 Britton–Robinson (BR) buffer at pH 6.0. The analytical signal of levonorgestrel showed a linear dependence on the concentration range from 5.03 × 10?7 mol L–1 to 1.01 × 10?5 mol L–1. The LOD and LOQ obtained were 9.09 × 10?8 mol L?1 and 3.03 × 10?7 mol L?1, respectively. The voltammetric method was employed for the quantification of levonorgestrel in real pharmaceutical formulations and urine samples. The results provided good concordance with the expected values. It makes the working electrode used here an interesting and less toxic option for the analysis of reducible substances in comparison with the HMDE. 相似文献
365.
Let (p) be the percolation probability of a d-dimensional bond percolation process on Z
d
. We prove that 1–(p) can be written as an absolutely convergent series in powers of (1–p)/p, provided that |(1–p)/p| is sufficiently small. This implies that (p) is an analytic function of the complex variable p, around p=1. 相似文献
366.
367.
The electronic coupling between symmetrically placed lone pairs or π electrons are calculated using semiempirical and ab initio methods and the results compared to experimental numbers. The agreement is satisfactory in cases when there is a small tendency for cancellation between contributions of different signs. We have found nonexponential behavior when the number of intervening cyclohexane units is increased in the case of phenyl endgroups. In this case as well as in the cases with exponential decrease, the CNDO /S method shows a similar behavior as that of the ab initio Hartree–Fock method, which suggests that the former method may be used to calculate the electronic factor in electron transfer systems. © 1992 John Wiley & Sons, Inc. 相似文献
368.
We have studied the influence of the relaxation effects on the different kinds of short range order structures which can be distinguished inFe 80 B 20 amorphous alloys by Mössbauer spectroscopy. The analysis of the distribution function of the hyperfine fields gives results on the variations of the chemical and topological short-range orders in good agreement with those known in literature. Attempt to give quantitative results is made. 相似文献
369.
370.