The brilliant reds in Vincent van Gogh’s paintings are slowly turning
white. To understand how these Pb3O4-based red pigments
degrade, chemists at the University of Antwerp, in Belgium, used X-ray powder
diffraction tomography to study a sample taken from van Gogh’s 1889 painting
“Wheat Stack under a Cloudy Sky.” The white circle on the painting indicates
the spot that they sampled. In the space between the sample’s reddish-orange Pb3O4
core and the light blue PbCO3 layer that surrounds it, the chemists
found plumbonacrite, 3PbCO3•Pb(OH)2•PbO. The chemists
propose a mechanism of how red lead degrades via plumbonacrite, involving
carbon dioxide and light.
Simple Tips That Lead To Physical Fitness - …
Source: Fitness Universe
Fitness is not something that you wish for, it is something that you go out and get for yourself. This article is going to show you ways that you can decide to do what it takes and get fit. Keep reading for tips and ideas on how you can make this happen.
Seattle’s Law Enforcement Assisted Diversion program (LEAD) has taken hold of the neighborhood in the past three years. Instead of sending a low-level offender to jail, the officer can offer the offender the option of taking them to the precinct, having them meet with a social worker, and becoming part of the LEAD program. From there, the offender’s crime is taken off the record, and they can take advantage of existing low-income assistance programs. Case workers work closely with the person to help them find housing, help them get health care, and generally support them in making life changes.
Lead ingot, presumably medieval, found in Østfold. It has a thin line engraved around the object 5-6 mm from the bottom, and seems to have had the same line where it is cut. It has equal marks on two sides, indicating that it has been held with pliers or another tool. We map the area among other things to determine whether there has been handicraft production there in earlier times, so it is an interesting find. Production of weights is a possible explanation, especially since the selected part will weigh about 1 ørtug, which is an old norse weight unit.