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111.
Santo M Giacomelli L Cattana R Silber J Blanco MM Schapira CB Perillo IA 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(7):1399-1407
The solvatochromism in 8-hydroxy-1,6-naphthyridin-5(6H)-one-7-carboxylic acid methyl ester (1), 5-hydroxy-1,7-naphthyridin-8(7H)-one-6-carboxylic acid methyl ester (2), and 4-hydroxy-2-methyl-1(2H)-isoquinolone-3-carboxylic acid methyl ester (3), has been studied in solvents of different polarity and hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) ability. The relative stabilities of isomers for these naphthyridine derivatives and their interaction with the solvent are reported. Two intramolecular hydrogen-bonded structures contribute to the ground state of compound 1. Temperature effects on the absorption bands were recorded to analyse the possible equilibrium between covalent and zwitterionic forms. The formation of zwitterionic species was observed only in HBD solvents, from which is inferred the solvent assistance in the proton transference. AM1 and PM3 semi-empirical calculations were used in support of the proposed interpretations. 相似文献
112.
Cabeza M Bratoeff E Flores E Ramírez E Calleros J Montes D Quiroz A Heuze I 《Chemical & pharmaceutical bulletin》2002,50(11):1447-1452
The pharmacological activity of several 16-bromosubstituted trienediones 4 and 5, 16-methyl substituted dienediones 6 and 7 and the 16-methyl substituted trienedione 8 was determined on gonadectomized hamster seminal vesicles by measuring the in vitro conversion of testosterone (T) to dihydrotestosterone (DHT) as 5alpha-reductase inhibitors and also the ability of these steroids to bind to the androgen receptor. Steroids 6 and 7 when injected together with T decreased the weight of the seminal vesicles thus showing an antiandrogenic effect. Compounds 5 and 6 reduced substantially the conversion of T to DHT and therefore can be considered good inhibitors for the enzyme 5alpha-reductase; however both steroids failed to form a complex with the androgen receptor. On the other hand compound 7 which showed a very small inhibitory activity for the enzyme 5alpha-reductase, exhibited a very high affinity for the androgen receptor and thus can be considered an effective antiandrogen. This compound also reduced substantially the weight of the seminal vesicles. Steroids 4 and 8 did not reduce the weight of the seminal vesicles and exhibited a low affinity for the androgen receptor; 8 showed a weak 5alpha-reductase inhibitory activity, whereas 4 exhibited a weak androgenic effect. 相似文献
113.
Santos Lidya B. Striebeck Maria V. Crespi Marisa S. Ribeiro Clovis A. De Julio Marcelo 《Journal of Thermal Analysis and Calorimetry》2015,122(1):21-32
Journal of Thermal Analysis and Calorimetry - Recently, biochar was introduced as a bioadsorbent material to remove various contaminants in effluents, such as pigments, dyes, heavy metals,... 相似文献
114.
Fernanda M. Prado Alexsandra C. Scalfo Sayuri Miyamoto Marisa H.G. Medeiros Paolo Di Mascio 《Photochemistry and photobiology》2020,96(3):560-569
Singlet molecular oxygen is a reactive species involved in biological oxidative processes. The major cellular targets of singlet molecular oxygen are unsaturated fatty acids in the membrane, as well as nucleic acids and proteins. The aim of this study was to investigate whether lipids and commercial hydroperoxides generate singlet molecular oxygen, in presence of nitronium and activated nitronium ion. For this purpose, monomol light emitted in the near-infrared region (λ = 1270 nm) was used to monitor singlet molecular oxygen decay in different solvents, with different hydroperoxides and in the presence of azide. Direct measurements of the singlet molecular oxygen spectrum at 1270 nm recorded during the reaction between lipids and commercial hydroperoxides and nitronium ions unequivocally demonstrated the formation of this excited species. 相似文献
115.
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117.
Marisa Maltez-da Costa Alfredo de la Escosura-Muñiz Arben Merkoçi 《Electrochemistry communications》2010,12(11):1501-1504
The catalytic ability of gold nanoparticles (AuNPs) toward the formation of H2 in the electrocatalyzed Hydrogen Evolution Reaction (HER) is thoroughly studied, using screen-printed carbon electrodes (SPCEs) as electrotransducers. The AuNPs on the surface of the SPCE, provide free electroactive sites to the protons present in the acidic medium that are catalytically reduced to hydrogen by applying an adequate potential, with a resulting increment in the reaction rate of the HER measured here by the generated catalytic current. This catalytic current is related with the concentration of AuNPs in the sample and allows their quantification. Finally, this electrocatalytic method is applied for the first time, in the detection of AuNPs as labels in a magnetoimmunosandwich assay using SPCEs as electrotransducers, allowing the determination of human IgG at levels of 1 ng/mL. 相似文献
118.
Josiane de Lima Souza Marcelo Kobelnik Clóvis Augusto Ribeiro Jorge Manoel Vieira Capela Marisa Spirandeli Crespi 《Journal of Thermal Analysis and Calorimetry》2009,97(2):525-528
Poly(3-hydroxybutyrate), PHB, has been structurally modified through reaction with hydroxy acids (HA) such as tartaric acid
(TA) and malic acid (MA). The crystallization kinetic of the samples was evaluated by isoconversional method through nonlinear
fitting to obtain the estimation for activation energy (E
a
) and pre-exponential (A) values. The thermal behavior of the crystallization temperature, 44.8 and 58.9 °C at 5 °C/min, and results obtained to the
average activation energy, 73 ± 9 kJ mol−1 and 63 ± 1 kJ mol−1, to PHB/MA and PHB, respectively, are suggesting that malic acid may be deriving plasticizer units from its own PHB chain.
PHB/TA show increase in the medium value of E
a, 119 ± 2 kJ mol−1 and T
c = 48.2 °C (at 5 °C/min), indicating that tartaric acid is probably interacts in different way to the of PHB chain (E
a=73 ± 9 kJ mol−1, T
c = 44.8 °C at 5 °C/min). 相似文献
119.
120.
We study a q-player variation of the impartial avoidance game introduced by Anderson and Harary, where q is a prime. The game is played by the q players taking turns selecting previously-unselected elements of a finite group. The losing player is the one who selects an element that causes the set of jointly-selected elements to be a generating set for the group, with the previous player winning. We introduce a ranking system for the other players to prevent coalitions. We describe the winning strategy for these games on cyclic, nilpotent, dihedral, and dicyclic groups. 相似文献