排序方式: 共有45条查询结果,搜索用时 0 毫秒
41.
Luiza N.H. Arakaki Ana Paula M. Alves Maria G. Fonseca José Geraldo P. Espínola 《Thermochimica Acta》2007,453(1):72-74
Thermodynamic data on interaction of Cu(II), Ni(II), and Co(II) with silica modified with ethyleneimine are obtained by calorimetric titration. The amount of ethyleneimine anchored on silica surface was estimated to be 0.70 mmol g−1. The enthalpies of binding Ni(II), Cu(II) and Co(II), are −3.59 ± 0.001, −4.88 ± 0.001, and −7.75 ± 0.003 kJ mol−1, respectively. 相似文献
42.
43.
Vera Lucia da S. Augusto Filha Oberto G. da Silva J. R. da Costa Albaneide F. Wanderley Maria G. da Fonseca Luiza N. H. Arakaki 《Journal of Thermal Analysis and Calorimetry》2007,87(3):621-625
Calorimetric titration was applied to study
the interaction of zinc, cadmium and mercury on surface of silica gel modified
with 2-aminoethanethiol, using 3-chloropropyltrimetoxysilane as precursor
silylating agent. The anchored Sil–SNH2 surface
gave 0.70 mmol g–1 of molecules covalently
bonded per gram of silica. This surface displayed a chelating moiety containing
sulfur and nitrogen basic centers, which are potentially capable of extracting
cations from aqueous solutions, such as MCl2 (M=Zn, Cd, Hg). This process of extraction was carried
out by the batch method when similar chemisorption isotherms were observed
for all cations.
The data were adjusted to modified Langmuir equation.
The sequence of the maximum retention capacity was Hg>Cd>Zn. The processes
of cation interactions showed exothermic enthalpies. The calculated ΔG values are in agreement with the spontaneity of
the proposed reactions and conformed to the values found by using Langmuir
model applied to these systems. The endothermic entropic values, as expected,
indicated that the reactions are favorable. 相似文献
44.
Gabriela Marcelino David Johane Machate Karine de Cssia Freitas Priscila Aiko Hiane Iriani Rodrigues Maldonade Arnildo Pott Marcel Arakaki Asato Camila Jordo Candido Rita de Cssia Avellaneda Guimares 《Molecules (Basel, Switzerland)》2020,25(24)
Carotenoids are vital antioxidants for plants and animals. They protect cells from oxidative events and act against the inflammatory process and carcinogenesis. Among the most abundant carotenoids in human and foods is β-carotene. This carotenoid has the highest level of provitamin A activity, as it splits into two molecules of retinol through the actions of the cytosolic enzymes: β-carotene-15,15′-monooxygenase (β-carotene-15,15′-oxygenase 1) and β-carotene-9′,10′-dioxygenase (β-carotene-9′,10′-oxygenase 2). The literature supports the idea that β-carotene acts against type 2 diabetes mellitus, cardiovascular diseases, obesity, and metabolic syndrome. Due to the many processes involved in β-carotene biosynthesis and metabolic function, little is known about such components, since many mechanisms have not yet been fully elucidated. Therefore, our study concisely described the relationships between the consumption of carotenoids, with emphasis on β-carotene, and obesity and type 2 diabetes mellitus and its associated parameters in order to understand the preventive role of carotenoids better and encourage their consumption. 相似文献
45.
José Geraldo de P. Espínola Evandro P. S. Martins Franklin P. Aguiar Haryane R. M. Silva M. G. Fonseca L. N. H. Arakaki Ercules E. S. Teotônio 《Journal of Thermal Analysis and Calorimetry》2011,106(2):601-606
The complex BiCl3·L (L = 1,10-phenanthroline) was synthesized and characterized by elemental analysis and infrared spectroscopy (IR). Infrared
spectroscopy data suggested that the nitrogen atom of the aromatic ring is bonded to the bismuth atom. The kinetic study of
thermal degradation was determined by non-isothermal thermogravimetry. Two methods based on integral equation of Coats-Redfern,
were necessary for determining the kinetic trip: the fitting method, known as the checking model and an iso-conversional method.
The latter gives the activation energy for each degree of conversion and the first, the kinetic model gives activation energy
and the pre-exponential factor for thermal decomposition processes that occur through a single simple mechanism. The kinetic
parameters, E
a and log A for the heating rates of 5, 10, and 15 min K−1, were determined considering the decomposition model denoted by F0/R1 in the range of degree of conversion between 0.065
and 0.71. 相似文献