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71.
72.
Santiago MB Vélez MM Borrero S Díaz A Casillas CA Hofmann C Guadalupe AR Colón JL 《Electroanalysis》2006,18(6):559-572
We present a carbon paste electrode (CPE) modified using the electron mediator bis(1,10‐phenanthroline‐5,6‐dione)(2,2′‐bipyridine)ruthenium(II) ([Ru(phend)2bpy]2+) exchanged into the inorganic layered material zirconium phosphate (ZrP). X‐Ray powder diffraction showed that the interlayer distance of ZrP increases upon [Ru(phend)2bpy]2+ intercalation from 10.3 Å to 14.2 Å. The UV‐vis and IR spectroscopies results showed the characteristic peaks expected for [Ru(phend)2bpy]2+. The UV‐vis spectrophotometric results indicate that the [Ru(phend)2bpy]2+ concentration inside the ZrP layers increased as a function of the loading level. The exchanged [Ru(phend)2bpy]2+ exhibited luminescence even at low concentration. Modified CPEs were constructed and analyzed using cyclic voltammetry. The intercalated mediator remained electroactive within the layers (E°′=–38.5 mV vs. Ag/AgCl, 3.5 M NaCl) and electrocatalysis of NADH oxidation was observed. The kinetics of the modified CPE shows a Michaelis–Menten behavior. This CPE was used for the oxidation of NADH in the presence of Bakers' yeast alcohol dehydrogenase. A calibration plot for ethanol is presented. 相似文献
73.
Hair color changes and protein damage caused by ultraviolet radiation 总被引:12,自引:0,他引:12
Santos Nogueira AC Joekes I 《Journal of photochemistry and photobiology. B, Biology》2004,74(2-3):109-117
Ultraviolet and visible radiations are known to damage hair. However, quantitative data relating damage to hair type, proteins and color to the radiation wavelength are missing. We studied the effect of UV plus visible, UVA plus visible, visible mercury-vapor lamp radiation and sunlight on (blended) virgin dark-brown, blond and red hair and (one head) virgin black and curly dark-brown hair. All hair types showed a substantial increase in protein loss in water after lamp and sun irradiation. The damaging effect of UVB was about 2-5 times higher than that of UVA plus visible radiation, depending on the hair type. Significant color changes were also observed in every hair type, after lamp and sun irradiation, being more pronounced for the light colored hairs. The luminosity difference parameter was the major contributor to the hair color changes, but significant changes in the red-green and yellow-blue parameters of every hair were observed. In this case, the damaging effect is ascribable mainly to UVA radiation. No significant changes in the mechanical properties or topography were observed in any case. We discuss these results in terms of hair type and composition and melanin types. 相似文献
74.
Esteso Ana Alemany M. M. E. Ortiz Angel Liu Shaofeng 《Central European Journal of Operations Research》2022,30(3):1101-1127
Central European Journal of Operations Research - Agri-food production must increase while food waste needs to be reduced for improving the position of farmers. To do so it is necessary to... 相似文献
75.
Ana M. Vargas 《Rendiconti del Circolo Matematico di Palermo》1995,44(2):273-282
LetM
e
0
be the maximal operator over segments of length 1 with directions belonging to a Cantor set. It has been conjectured that
this operator is bounded onL
2. We consider a sequence of operators over finite sets of directions converging toM
e
0
. We improve the previous estimate for the (L
2,L
2)-norm of these particular operators. We also prove thatM
e
0
is bounded from some subsets ofL
2 toL
2. These subsets are composed of positive functions whose Fourier transforms have a very weak decay or are supported in a vertical
strip.
Partially supported by Spanish DGICYT grant no. PB90-0187. 相似文献
76.
LetEçS 1 be a set with Minkowski dimensiond(E)1. We consider the Hardy-Littlewood maximal function, the Hilbert transform and the maximal Hilbert transform along the directions ofE. The main result of this paper shows that these operators are bounded onL rad p (R2) forp>1+d(E) and unbounded whenp<1+d(E). We also give some end-point results. 相似文献
77.
Federico Sánchez-Bringas Ana Irene Ramírez-Galarza 《Annals of Global Analysis and Geometry》1995,13(2):129-140
LetM be a compact orientable surface,I:M R4 an immersion of classC
r
and
a normal unitary smooth vector field. We prove that in the space of pairs (I,
) the family of pairs all whose umbilical points are Darbouxian is generic. 相似文献
78.
79.
J. A. E. Carrillo J. A. S. Lima A. Maia Jr. 《International Journal of Theoretical Physics》1996,35(9):2013-2018
The spectrum of massless bosonic and fermionic fluids satisfying the equation of statep=(–1) is derived using elementary statistical methods. As a limiting case, the Lorentz-invariant spectrum of the vacuum (=0,p=–) is deduced. These results are in agreement with our earlier derivation for bosons using thermodynamics and semiclassical considerations. 相似文献
80.