Wikipedia:Reference desk/Archives/Science/2008 March 7

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March 7

multivitamins smell bad?

Why do most multivitamin tablets smell so bad?--Sonjaaa (talk) 01:16, 7 March 2008 (UTC)

Usually the B vitamins are responsible for the smell of multivitamins. [1][2] Dforest (talk) 01:48, 7 March 2008 (UTC)

Obvious follow up question: Why? The entries makes no mention of odors or smells. --70.167.58.6 (talk) 22:36, 9 March 2008 (UTC)

Smelly wet dogs

Why do dogs smell worse when they're wet? When they are dry they usually smell fine, but when they get wet a very distinctive, "wet-dog" odor that seems to permeate everything (it's quite stinky in my opinion) and I was wondering why exactly this happens. Thanks! --71.98.14.31 (talk) 23:48, 6 March 2008 (UTC)

According to the following study, some amount of change in odor results from the different partition coefficients when water is added to the hair. However, "the variety of differences indicates a probable chemical or biochemical reaction on the hair." Compounds Responsible for the Odor of Dog Hair Coat This appears to suggest that an increase in bacterial activity is a likely culprit. Dforest (talk) 05:20, 7 March 2008 (UTC)

Does an OH group make a molecule polar

Does an -OH make a molecule polar? Thanks. —Preceding unsigned comment added by Legolas52 (talk • contribs) 05:48, 7 March 2008 (UTC)

It almost always would as the H atom develops a positive charge and the O atom has lone pairs of electrons with a negative charge. Examples re water ethanol hydroxylamine hydroxyl glycerol glucose. All these are polar. Graeme Bartlett (talk) 08:45, 7 March 2008 (UTC)

For very large molecules, such as cholesterol or free fatty acids, hydroxyl and carboxyl groups can make one end of the molecule polar and while the other remains non-polar (this combination is known as being amphipathic). This is especially important in biological cell membranes. (EhJJ)^TALK 12:31, 7 March 2008 (UTC)

The only way a molecule could be non-polar and have OH groups is if the OH groups were arranged symmetrically around a centre of inversion - can't think of an real example of this maybe something like HO-CC-OH (triple bond in middle)87.102.83.54 (talk) 12:46, 7 March 2008 (UTC)

Must ... resist ... polar ... HO-HO-HO ... joke. --Sean 15:16, 7 March 2008 (UTC)

In addition to the doubtful non-polarity of HOCCOH (ethyne glycol) should it even exist (the angle between O-H bonds can freely rotate, ruining the perfectly zero dipole moment), if you're discussing polarity to guess something's solubility in water, you also have to consider hydrogen bonding. A chemical capable of making hydrogen bonds (by having hydrogens on fairly electronegative atoms, or lone pairs on electronegative atoms involved in fairly polar bonds) will generally be miscible with water even in the absence of a dipole moment. It will just generally suck at dissolving salts. Someguy1221 (talk) 15:33, 7 March 2008 (UTC)

definitely not. Its certainly possible to stick OH groups in a non-polar molecule. Not common, but thats not a safe rule to go by either. Furmanj (talk) 01:22, 8 March 2008 (UTC)

Depending on the chemistry of the rest of the molecule, it could or could not, as Fur indicates above. However, a hydroxyl group will give the compound resident/local polarity due to hydrogen bonding with aqueous solution/polar solvents. Wisdom89 _{(T / ^C)} 03:09, 8 March 2008 (UTC)

Tumors

Do all malignant tumours neccessarily lead to cancer? Why or why not?

Disclamier: This is neither for a competition nor for homework. —Preceding unsigned comment added by Invisiblebug590 (talk • contribs) 08:25, 7 March 2008 (UTC)

Any tumor that is malignant is, by definition, cancerous. If a tumor is not cancerous it is benign. Some benign tumors will develop into cancer. Someguy1221 (talk) 08:33, 7 March 2008 (UTC)

Neat answer. Richard Avery (talk) 08:43, 7 March 2008 (UTC)

On the other hand, not all malignant tumors lead to death. Our watchful waiting article doesn't specifically mention this, but that strategy can often be the best one for an elderly patient with relatively non-aggressive prostate cancer (as mentioned in that article here).

Atlant (talk) 13:04, 7 March 2008 (UTC)

conservation of energy

suppose a balloon is kept in air so that it rises and both it's kinetic as well as potential energy increases. how is the Conservation of Mechanical Energy conserved here ? --scoobydoo (talk) 12:19, 7 March 2008 (UTC)

Its potential energy may increase but at the same time a corresponding but heavier equal volume of air is descending and the potential energy of the air is decreasing. --BozMo talk 12:29, 7 March 2008 (UTC)

Expanding on BozMo's explanation: if the balloon has mass m₁ and the equivalent volume of air has mass m₂ then the net upwards force on the balloon is (m₂ - m₁)g. If the ballon ascends a distance h then it will be travelling at a velocity v where v²=2(m₂ - m₁)gh/m₁. At the same time, a mass m₂ of air has been displaced downwards by a distance h. So we have

Kinetic energy gained by balloon = m₁v²/2 = (m₂ - m₁)gh

Potential energy gained by balloon = m₁gh

Potential energy lost by displaced mass of air = m₂gh

so k.e. gained by balloon + p.e. gained by balloon - p.e. lost by displaced air = 0 and we have conservation of energy. Gandalf61 (talk) 16:30, 7 March 2008 (UTC)

WARFARIN USE

Medical question removed
If you would like to know about warfarin, click on the blue link. But Wikipedia does not give out medical advice. If you are concerned about a friend or relative's medication, I would highly suggest you direct your questions to the prescribing doctor. Someguy1221 (talk) 16:00, 7 March 2008 (UTC)

Metal specs

what is the differance between a vascomax300cmetal and a maragin300c metal? 65.218.254.135 (talk) 18:52, 7 March 2008 (UTC)RUBEN

Vascomax appears to be a registered trademark name for maragin steel see http://www.maraging.com/maraging.html

Is there some reason that prevents you typing 'vascomax' or 'maragin' into a search engine?87.102.93.198 (talk) 11:08, 8 March 2008 (UTC)

somatic cell hybrid panel

Chromosome mapping of the DRM gene A somatic cell hybrid panel (Oncor) was hybridized with a 32P-labeled 1.2-kb human 5) DRM cDNA fragment according to the manufacturer’s protocol.

What is a 'somatic cell hybrid panel'? ----Seans Potato Business 19:56, 7 March 2008 (UTC)

My guess is dot blot panel of DNA from different rat or mice cell lines which include known portions of human chromosomes. The cell lines would be made by fusing human cell lines with mice/rat cell lines by somatic hybridisation. David D. (Talk) 21:45, 7 March 2008 (UTC)

graphite

when i took a stick of graphite and wraped wires on ech end and sent a current through it it began smoking and it looked wet. but it wasn't melting, was it? wat was it doing? —Preceding unsigned comment added by Steweydewey (talk • contribs) 23:59, 7 March 2008 (UTC)

Thermal_oxidation? Did it get hot? The smoke was likely solid carbon dust in a flow of CO and CO2 coming off. If you did the same thing in a vacuum or under an inert gas this wouldn't happen. Furmanj (talk) 01:08, 8 March 2008 (UTC)

Are you sure it was pure graphite? If you used a pencil lead, then it probably contained powdered graphite mixed with clay and glue. The glue would have melted and smoked. --Heron (talk) 14:24, 8 March 2008 (UTC)