26 research outputs found
Quinazoline carboxylic acids, part X. Synthesis of 1-methyl-2,4-dioxo-quinazolin-3-yl-acetic acid, 2,4-dioxo-quinazolin-1-yl-acetic acids, 2,4-dioxo-1,3-quinazolinediacetic acids and their esters
Effects of aerobic exercise training on physical performance during myeloablative therapy
On the symmetry of tsumcorite group minerals based on the new species rappoldite and zincgartrellite
Analyse gekoppelter dynamischer Systeme unter Verwendung der erweiterten Hamiltonfunktion für klassische und der nicht-konservativen Hamiltonfunktion H ∗n für Lagrange-Systeme höherer Ordnung
Syntheses of heterocycles with 5-phenyl-isoxazolium salts, III. Synthesis of pyrrolo[1,2-a]quinazolin-5-ones
A combined synchrotron powder diffraction and vibrational study of the thermal treatment of palygorskite–indigo to produce Maya blue
The heating process (30–200 ºC) of a palygorskite-
indigo mixture has been monitored in situ and
simultaneously by synchrotron powder diffraction and
Raman spectroscopy. During this process, the dye and the
clay interact to form Maya blue (MB), a pigment highly
resistant to degradation. It is shown that the formation of a
very stable pigment occurs in the 70–130 ºC interval; i.e.,
when palygorskite starts to loose zeolitic water, and is
accompanied by a reduction of the crystallographic a
parameter, as well as by alterations in the C=C and C=O
bonds of indigo. Mid- and near-infrared spectroscopic
work and microporosity measurements, employed to study
the rehydration process after the complex formation, provide
evidence for the inhibition of the rehydration of MB as
compared with palygorskite. These results are consistent
with the blocking of the palygorskite tunnel entrance by
indigo molecules with a possible partial penetration inside
the tunnels. The surface silanols of palygorskite are not
perturbed by indigo, suggesting that MB is not a surface
complex