Essays on Residues

The environment is everything that surrounds us. It involves not only the natural elements that the word “environment” entails but also people and the man-made components of the world. Nor is the environment restricted to the outside, it also involves the indoor sections in which we live and work. The environment, therefore, is much more than simply the ozone layer and the ocean. It is the soil, air, water, lands, animals, houses, restaurants factories and all that they contain. Anyone who uses pesticides indoors or outdoors, in a city or a country, needs to consider the way that pesticide ...

1. a. The pKa value of an amino acid is an indication of how strong or weak an amino acid is, based on the said acid’s dissociation constant. An amino acid that has a high pKa value is weaker than on that has a low pka value. Given that an acid’s dissociation constant is Ka, the pKa value is given by the formula: pKa = -log10Ka pH = pKa + log ([A-]/[HA]),It follows that for Cys12, 7.4= 7.2 + log([Cys-]/[HCys]) 7.4-7.2 = log([Cys-]/[HCys]) 0.2 = log([Cys-]/[HCys]) 100.2= Cys-/HCys Therefore, Cys-/HCys = 10-4Similarly, ...

Lignin Chemistry

Lignin History Lignin is a plant-derived biopolymer with several applications. It is considered an effective alternative to chemically synthesized plastics that pose serious environmental problems during manufacture and disposal. Lignin is often obtained as a byproduct in paper and pulp manufacture. Lignin has to be dissolved to obtain cellulose from wood. In 1838, Anselme Payen discovered that wood contained cellulose, and oxidizable coatings (later called lignin) that bind the cellulose together (McCarthy and Islam, 2000). This coating material could be removed from wood after acid treatment and washing with an aqueous alkali solution (McCarthy and Islam, 2000). Later, several ...