Biodegradation and toxicological evaluation of lubricant oils
The aim of this work was to compare different toxicity levels of lubricant oils. The tests were performed using the earthworm (Eisenia andrei), arugula seeds (Eruca sativa) and lettuce seeds (Lactuca sativa), with three types of contaminants (mineral lubricant oil, synthetic lubricant oil and used lubricant oil) for various biodegradation periods in the soil. The toxicity tests indirectly measured the biodegradation of the contaminants. The samples were analyzed at t0, t60, t120 and t180 days of biodegradation. The used lubricant oil was proved very toxic in all the tests and even after biodegradation its toxicity was high. The mineral and synthetic oils were biodegraded efficiently in the soil although their toxicity did not disappear completely after 180 days.
Recent development on biodegradable nanolubricant: A review
Naturally, biodegradable oil has better viscosity index, pour point, flash point, good tribology properties and its environmental friendly. Even though biodegradable lubricant is one of the best choice for lubrication purposes, however the properties are slightly lesser than mineral oil. A common solution for this problem is to provide effective additives into the base stock of biodegradable oil which leads to significant improvement to the lubricant by enhancing thermal properties, tribological properties and anti-oxidation capability. Nanoparticles are a type of effective additives which provides promising approach to enhance the biodegradable lubricant's properties. In this article, we reviewed the current progress and recently published data related to biodegradable lubricant, nanoparticles and its improvement on the biodegradable lubricant properties.
Percussion marks on bone surfaces as a new diagnostic of hominid behaviour
Since stone tool cut marks and carnivore tooth marks were first described systematically on Plio-Pleistocene archaeological bone1,2, bone surface modification has played a prominent role in interpreting early archaeological site formation and hominid behaviour3–15. Here we introduce a new class of bone surface modification, which we call percussion marks. Percussion marks were produced during experimental breakage of marrow bones, and occur as pits or grooves impressed on a bone's surface by natural protrusions on the granitic hammerstone and anvil used. Although percussion marks can superficially mimic carnivore tooth marks, they nonetheless are closely associated with hammerstone impact notches and show consistent micromorphological features which distinguish them from tooth marks and other classes of bone surface modification. Given indications of prehistoric hammer-stone breakage of marrow bones1,7, an awareness of percussion marks is critical for accurately identifying the biological agents of bone modification at archaeological sites and provides a new diagnostic of carcass processing by hominids.