Question Corner

Reducing pollution

QUESTION: Can we use methanol or ethanol bio-fuels in motor vehicles and pumpsets? Is it helpful in reducing pollution?

K. Satyanarayana, Hyderabad.

ANSWER: Alternative fuels are now being explored particularly because of shortage of petroleum products and this approach could be successful in the near future. The three possible substances often mentioned as petrol substitutes are methane (CH₄), Hydrogen (H₂) and Methanol (CH₃OH). All the three have been successfully tested as fuels in slightly modified forms of existing internal combustion engines. In each case, pollutant emissions were found to be reduced.

Methanol or ethanol itself or blended with Gasoline (Gasohol) can be used as fuel in a suitably designed internal combustion engines. Gasohol has a high octane rating and does not require addition of Pb(C₂H₅)₄. It cuts down the exhaust emission upto 50% for CO and NO_x.

Many efforts have been made in developed countries in reducing petrol consumption by 50% of amount used two decades ago. Gasohol is likely to play a useful role in party meeting the fuel needs in USA. Almost one third of Brazil's cars run on pure ethanol and many cars run on ethanol/ petrol mixture. Several countries use natural gas as fuel in cars. In Italy, about three lakh cars run on compressed natural gas.

G. Brindha, Tiruvarur, T.N.

Yellow colour of urine

QUESTION: Why does urine become yellow in colour when we take certain medicines or tonics?

K. Ananthanarayanan, Kanyakumari, T.N.

ANSWER: Yellowing of urine is due to the predominant rise in the unconjugated bilirubin in the blood. Usually this rise occurs either in hemolytic jaundice, which is the result of increased destruction of RBC or obstructive jaundice, which is the result of either bile stone blockage of commom bile duct or damage to the liver cells. Administration of certain drugs in the patients can also result in the rise of unconjugated bilirubin there by causing the yellowing of urine in them.

Drugs like Novobiocin can interfere with bilirubin conjugation, which is essential for its excretion through bile. This results in the increase of conjugated bilirubin in the blood. Even some common medicines like paracetamol and sulfonamide are hepatotoxin. So they cause mild damage to the liver cells which results in the increase of bilirubin level in the blood. Acute overdose of paracetamol can produce severe hepatic necrosis. Drugs like hydrozine derivatives may produce clinical syndrome resembling viral hepatitis. So in the persons, during administration of these drugs the urine becomes yellowish.

In the case of tonics the yellowing of urine is mainly due to the excretion of B-complex vitamins, which form the major constituent in them. These vitamins are water soluble vitamins and absorption of these vitamins is very rapid. But they are rarely stored in the liver except vitamin B-12. So the excess vitamins are readily excreted through urine and in such condition they impart yellow colouration to the urine. Yellow colouration is mainly due to the presence of excreted riboflavin, which is a yellow-green fluorescent compound.

S. Palaniappan, Pudukottai, T.N.

Send this article to Friends by E-Mail

Section  : Science & Tech
Previous : Pointing fingers
Next     : CAT detects auto component faults