Wikipedia:Reference desk/Archives/Science/2007 February 14

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

February 14

Coating on medications...

my little sis is working on a science fair project and she asked my since I am a PA about the coating on the medications....I have no clue about that, I just know how meds work. If anyone could explain the different coatings and what they are composed of, i would appreciate it as I have no clue.

It's called enteric coating, and regrettably our article doesn't have much on the subject. But you could try searching for the term. (BTW read the article anyway). Anchoress 00:32, 14 February 2007 (UTC)

There are lots of different coatings, and most aren't enteric. Some are mostly decorative. One coating, used to produce a shiny hard surface is lactose; there are others that produce film coats, granulations, and seal coats. You may be able to find interesting things by searching for various combinations of pharmaceutical coating & other key words. Or have a look at [1], which I found that way (has some examples and lists of ingredients). - Nunh-huh 03:11, 14 February 2007 (UTC)

Oops, sorry, my bad. I thought all coatings were enteric (why bother coating them otherwise?). Sorry if I misled anyone. Anchoress 14:05, 15 February 2007 (UTC)

Some medications are very bitter, and coatings prevent you from tasting them. There's also a touch of aesthetics involved, and they help you identify drugs as well. - Nunh-huh 01:47, 17 February 2007 (UTC)

The coating on panadol is supposed to make it easier to swallow, supposedly Nil Einne 14:18, 17 February 2007 (UTC)

I once had an ulcer in my upper colon, and took some pills which had a coating that would dissolve when and only when they hit the upper colon. Apparently the pH there is very specific. Cool and bizarre. --TotoBaggins 03:35, 14 February 2007 (UTC)

Enteric coatings refer to coatings that resist the hydrochloric acid in the stomach. These particular coatings are used for drugs that might be broken down by this acid. The medication thus leaves the stomach intact and the coating is broken down in the small intestine where the pH is higher and the drug is then absorbed from the small intestine. Hexane2000

Why is this fungus dropping liquid?

The weather had been dry for weeks when I saw this fungus. All the time more drops of liquid slowly emerged to its lower side. When the drops were big enough, they dropped to the ground and soon new drops emerged. What was happening in that fungus? What was this liquid? Did fungus suck water from the tree? Or did the water somehow concentrate from quite dry air? I already asked this in Finnish wikipedia, but no one knew Tuohirulla puhu 00:45, 14 February 2007 (UTC)

ok well one quick question. was it morning or night time when you saw this? if it was morning then it might of been condensation building up on the fungi. however if that isnt the case then maybe the fungi is releasing its spores to make more fungi, or maybe its extracting too much from the tree and its leaving the waste? inanyways the time of this would be better for helping ya Maverick423 17:47, 14 February 2007 (UTC)

It was middle day, if I remember right. Tuohirulla puhu 18:05, 15 February 2007 (UTC)

Some fungi literally melt away towards the end of the spore carrying bodies life eg inkcap (Coprinus comatus) - I don't think that is the case in the example in this case - fungi can suck water from a tree, they also digest cellulose from a tree - a by-product is water. See [2]:

"Once established at the new site the fungus digests the wood as an energy source. Wood is made up of cellulose and lignin. Cellulose is a carbohydrate and is completely metabolized by the fungus and breaks down into the carbon dioxide and water.

                   Cellulose ---- carbon dioxide + water

Serpula possesses an very impressive capability! The fungus can use the water it produces from breaking down the cellulose (metabolic water) for further growth. Sometimes so much water is produced that the wood drips water droplets. This ‘weeping’ gives the fungus its species name (= lacrymans)."

- this isn't the fungus you asked about - but it does live on wood - I'd guess something similar is happening with your fungus.83.100.158.13 20:09, 14 February 2007 (UTC)

Thanks for answering! Maybe it was like this going on Tuohirulla puhu 18:05, 15 February 2007 (UTC)

Round object

If I would tell you that I saw a round bright object floating above road, would you recommend me to see a doctor, or would you have any natural explanation for such? Lets say if the object would have been yellow, maybe partially transparent, and about of size of football, about 10-20 metres from me. It would have moved slowly, changed its direction, and suddenly disappeared. There would have not been thunder nearby so it would have not been a thunderball.Nitsimagoi

Sounds like Ball lightning, it's a rare and not well understood phenomenon and is not exclusivley linked to storms or normal 'lightning conditions'. Vespine 01:25, 14 February 2007 (UTC)

I have a feeling it was not electric. It was calm and silent. I imagine ball lightnings more "argessive". There was no sparkles or "sound of electricity". And if there was no thunder how electric ball could appear? Nitsimagoi 13:20, 14 February 2007 (UTC)

To me its sounds like a balloon. Was it night time? If so it could have been a headlight, or a beam of light shining on something, or even a reflection in a window. GB 01:31, 14 February 2007 (UTC)

It was night and ball was bright, so it was not a balloon. It was quite close to ground, only few metres high. There was no cars of houses, just a road on forest. I am sure its structure was ball and not reflection or anything else, but i have no idea what it was. Exept of course if it was hallicination Nitsimagoi 13:16, 14 February 2007 (UTC)

To me, it sounds like a ghost light. They're almost commonplace now.--Shantavira 08:49, 14 February 2007 (UTC)

Article about ghost light dont really explain what they are. Nitsimagoi 13:16, 14 February 2007 (UTC)

Explanations for the various ghost lights varies for each light, so you have to look at the listed articles. In several cases the lights correspond with distant highways. (SEWilco 04:39, 15 February 2007 (UTC))

If you would see this kind of thing, would you tell anybody? I am not going to tell anybody about this, not even to best friends (exept here). I dont want people to think I am mad. Nitsimagoi 13:16, 14 February 2007 (UTC)

What if you are mad, and just don't know it:]Hidden secret 7 17:38, 14 February 2007 (UTC)

what you saw was swamp gas reflecting off the remaining rays of sunlight to form a ball in the sky roughly 10 to 20 meters in diameter. its common MIB[3] stuff ya know. Maverick423 18:08, 14 February 2007 (UTC)

It sounds like you saw the sun. Via optical illusion or simply human-error in perception, you could mistake its characteristics. This explanation is the simplest - human vision has a large psychological component that makes it difficult to be very certain of what you saw. Nimur 20:32, 14 February 2007 (UTC)

It's very hard to judge the distance to things that are up in the air - further than maybe 10 to 20 meters away and at night. So a good first assumption is that you really don't know how far away it was - and therefore how big it was. For example - on an even slightly misty night, the moon might appear as you describe. It's also possible that it was the top of a water tower which are roughly spherical and lit up at night. Given some weird assumptions about temperature inversions in the air - maybe it was a mirage of sorts (that's a bit of a stretch). Then we can go with weather balloons...who knows... SteveBaker 03:49, 15 February 2007 (UTC)

This isn't exactly on-topic, but it might make you smile. Winston Churchill was once given a report by the Admiralty, and in the margin, next to a contentious paragraph, he wrote "Round objects!" (his euphemism for "Balls!"). Some other person saw the annotated report and asked "Who is Round, and to what does he object?"  :) JackofOz 04:01, 15 February 2007 (UTC)

Showing that Volts per meter equal Newtons per Coulomb

I'm having a little trouble with this. I just need to make sure I'm doing/did this correctly( I apologize that it isn't in a nice Wikipedia math format, but I don't know how to do that).

V/m = N/C (m^2 * kg * 1/s^3 * 1/A) / m = (kg * m/s^2) / (s * A) Now do I cross multiply and get this: (m^2 * kg * s/s^3 * A/A) = (kg * m^2/s^2) Now can I dive both sides by kg and m^2 and get this: (1/s^2) = (1/s^2)

So A. Is this close to being right? and B. Where did I go wrong if it isn't ? Thanks a lot in advance. Deltacom1515 02:28, 14 February 2007 (UTC)

Easier to just cross multiple q*V = N*m. Both are energy terms (electron Volts, Newton-meters). --Tbeatty 02:54, 14 February 2007 (UTC)

So both sides just reduce down to Joules then, right? Deltacom1515 03:34, 14 February 2007 (UTC)

See Volt. --Tbeatty 04:57, 14 February 2007 (UTC)

Stable Transfection

Hi All

How does cotransfecting a cell line with two plasmids yeild a stable transfection? It seems a common practice to transfect with two plasmids: the plasmid carrying the gene of interest - to be integrated into the host genome - and another plasmid to help with selection i.e. antibiotic resistance. Do we assume that if one plasmid gets in the other will also?

Thanks for your help

Mikmd 03:36, 14 February 2007 (UTC)

"Poor representation"?

What does it mean for a code to be "poorly represented" in genes? Here's the original question that's stumped me:

Researchers found that the arginine code AGG is poorly represented in genes of E.coli. Interestingly, they also found that this triplet, when present, binds to the ribosome 7-9 base pairs upstream from the starting ATG triplet (methionine). What does this information suggest in regard to the AGG codon?
A. it is a codon rarely found in this bacterium
B. it is conserved in most prokaroytic organisms
C. it may have a regulatory function in the cell
D. both B and C
E. A, B and C

I know for a fact that the answer is C. If someone cold explain to me what "poorly represented" means, then maybe i could figure out what's wrong with choices A and B (my original answer was E). --M1ss1ontomars2k4 ^{(T | C | @)} 04:05, 14 February 2007 (UTC)

I believe in this case "poorly represented" means that out of the six codons for arginine, the AGG triplet accounts for only a small percentage of arginine codons in the E.Coli genome. Since we have the sequence of the E.Coli genome, we can count all of the arginine codons and assign a codon usage bias. This does not completely explain the answer since we don't know what the regulatory function does. It may simply have a deliterious function. I would like to answer A and C, but I guess thats not an option. Mikmd 04:20, 14 February 2007 (UTC)

Are you sure its "C"? It seems to me that, as Mikmd explains, the very definition of "poorly represented" in this context would mean that "the codon is rarely found in this bacterium". Thus, notwithstanding "rarely" is a subjective term, "A" would appear to be true. "C" could certainly be inferred from the information provided, and B would merely be speculative. If "A and C" is not a possible answer, I would have to go with "A" alone. Rockpocket 09:19, 14 February 2007 (UTC)

The AGG codon is translated slowly in E. coli even at very low expression levels
--JWSchmidt 21:51, 14 February 2007 (UTC)

Geographic tongue- how did it get its name?

Above is a discussion of the malady Geographic tongue[link]. How did that get its name? Geography is the study of the Earth... what's the connection between that and tongues? 71.112.142.123 05:29, 14 February 2007 (UTC)

It's named because it looks like a map. - Nunh-huh 06:25, 14 February 2007 (UTC)

I had the same question, and the "looks like a map" answer was my guess, too, but is anyone sure? Our article doesn't say. —Steve Summit (talk) 14:06, 14 February 2007 (UTC)

I'm sure. I fixed the article, with reference. --TotoBaggins 16:10, 14 February 2007 (UTC)

Are microwave ovens or microwave heated food dangerous?

I recently read an article that said Russia banned microwaves because they are harmful to humans. We've all been using microwave ovens for some time now and they are substantially integrated into our lifestyles, and we are exposed to microwaves from these devices constantly and we eat microwaved food more than probably fast food. Is there evidence to support the claim that microwaves are harmful to one's health?

24.108.180.68 05:45, 14 February 2007 (UTC)

No, of course not. Unless you stick a part of your body into the microwave or your microwave is leaky. --M1ss1ontomars2k4 ^{(T | C | @)} 05:53, 14 February 2007 (UTC)

Microwave ovens form a resonant cavity with a frequency around 2.45 GHz. The cavity is much larger than the wavelength so a lot of standing waves form in the cavity. The FCC has some frequencies that it allows unlimited electromagnetic radiation (13.56 MHz is another frequency that comes to mind). For the same unlimited power regulations, micrawave ovens share the same frequency band as some wireless routers and portable phones (though, not cellphones). The ovens should not leak EM radiation if they are working properly. Microwaves excite molecules which turn into heat. The heated food does not reradiate microwave energy. --Tbeatty 06:02, 14 February 2007 (UTC)

It's energy transfer (more specifically, energy conversion). Unless you're saying that electric stoves will cause food to carry a charge, microwaved food shouldn't radiate microwaves either. There are, however, other health concerns such as microwaves not being able to kill bacteria as reliably, which is probably the only downside to using microwave ovens over conventional cooking methods. There was a rumor that microwave ovens destroy nutrients and cells, but according to the microwave oven article, it's been proven that conventional cooking is more destructve (which is probably directly related to the more reliable bacteria killing). --Wirbelwindヴィルヴェルヴィント (talk) 06:41, 14 February 2007 (UTC)

We need to remember that microwaves use electromagnetic radiation, not any type of ionizing radiation from particle decay. Electromagnetic radiation is also known as "light" [Mαc Δαvιs] X (How's my driving?) ❖ 17:20, 14 February 2007 (UTC)

It's not correct to say that electromagnetic radiation radiation is is never ionizing. Gamma rays and X-rays are both EM and ionizing, which is why your dentist wears that stylish lead apron. --TotoBaggins 18:55, 14 February 2007 (UTC)

In the early days of microwave ovens in the home, consumer advocates worried about microwaves leaking out through the door seals and causing damage such as cateracts in the users. The consumer magazines such as Consumer Reports did tests to see how much leakage there was, as when a paper towel was caught in the crack of the door. From the first there were mechanical interlocks to prevent the oven from operating with the door open, but it was a legitimate concern. Edison 05:48, 15 February 2007 (UTC)

Even a properly functioning microwave leaks a little radiation. Bring your 802.11 enabled device near an operating microwave oven and watch your signal quality drop. It's nothing to be particularly worried about, though. -- mattb @ 2007-02-15T05:58Z

Unless you need your wireless signal! WP:RD/S gets a lot of posters who seem to have life-threatening ailments and choose to come here for internet-based medical attention. In such cases, microwave interference might be very dangerous. Nimur 01:14, 16 February 2007 (UTC)

I think the danger lies in microwave oven usage. For example putting any metallic substances in there, or types of plastic that could melt and the toxins enter your food. I've read about people getting burns from overheated water (for tea) and when the teabag is inserted into the mug, it causes a sufficiently violent reaction to cause spillage. I've also witnessed a squash (vegetable) exploding from the pressure build-up and actually blowing open my microwave door, splattering squash all over. However I think gas stoves can be just as, or more, dangerous - so why not ban these? Electric stoves are the safest to use. Sandman30s 11:13, 16 February 2007 (UTC)

From the manual of a microwave oven I infer that they are both safe and dangerous. I am assured that it's safe by this passage:

Your oven [...], is one of the safest of all home appliances. [...] Microwave energy is converted completely to heat when it enters food, leaving no “left over” energy to harm you when you eat your food.

But I must think it's not that safe because there are pages of safety warnings. – b_jonas 20:50, 18 February 2007 (UTC)

Which way does ATP synthase face in bacteria?

Is the F₁ subunit on the inside or the outside of the cell membrane? --M1ss1ontomars2k4 ^{(T | C | @)} 05:55, 14 February 2007 (UTC)

Inside. − Twas Now ( talk • contribs • e-mail ) 06:35, 14 February 2007 (UTC)

Caveat lector: I have no expert knowledge of ATP synthase in bacteria, but if you look at the picture I've provided and consider endosymbiotic theory, then you might see how I arrived at this conclusion. − Twas Now ( talk • contribs • e-mail ) 08:20, 14 February 2007 (UTC)

Mitochondria are not found in bacterial cells - only in eukaryotic cells. (Having said that, mitochondria themselves might be distant descendants of prokaryotic cells, such as bacteria.) Since bacteria lack organelles such as mitochondria, the ATP synthase must be inside the cell.Hexane2000 08:47, 14 February 2007 (UTC)

Twas Now's argument was based on the analogy between bacteria and mitochondria. That's why the link to endosymbiotic theory was provided. --NorwegianBlue ^talk 18:12, 14 February 2007 (UTC)

Our ATP synthase article says some bacteria (primarily Gram-negative) have ATP synthase, but it doesn't say which direcction the ATP synthase faces. However, I think I agree with Twas Now. My thinking is that, aside from the analogy to mitochondrion, it would probably be easier to keep the cytosol cleaned of H+ than keep the ECF free of H+. And isn't ATP created using the F₁ subunit? The bacteria wouldn't generate ATP outside the cell and pump it back in, would it? --M1ss1ontomars2k4 ^{(T | C | @)} 20:26, 14 February 2007 (UTC)

The ATP-binding part is inside bacterial cells. --JWSchmidt 21:42, 14 February 2007 (UTC)

Op amp noise

Any idea how to measure the voltage noise source in an operational amplifier? I've found some information on how to calculate theoretical values, but what's a good way to measure it in practice? Thanks, 129.16.121.81 09:55, 14 February 2007 (UTC)

Did you mean the noise of the input to the op-amp (and not the noise of the power supply or output?)

Noise is not easy to measure easily - if you connect your source to an oscilloscope you might be able to see the noise if it is significant.

Is the input a sine wave, fixed voltage or something else? One method of calculating the noise of a signal is to sample it, subtract the expected pure signal and compare the overal magnitudes or powers of the two signals (to give a signal to noise ratio). However note that the sampling process may introduce noise of it's own.

In the mean time there are numerous articles on noise, electronic noise and similar topics. I don't know if any of these will be of use.83.100.158.13 10:31, 14 February 2007 (UTC)

The page Distortion measurement gives some hints on measuring noise in audio systems - this can also apply to higher frequencies.83.100.158.13 10:33, 14 February 2007 (UTC)

Try shorting the inputs together. If the op-amp has a low enough offset voltage, you'll find its output isn't slammed into one of the power rails and the AC component of the output will be the effective input noise multiplied by the amp's open loop gain.

If it does slam the rails, though, connect the output back to the inverting input through a large value resistor and connect a largish value capacitor from the inverting intput to the ground (reference voltage). This will stabilize the op-amp's DC gain at 1 while allowing its AC gain to approach the open loop value (for frequencies well beyond the time constant of your RC network). Then proceed as above.

Atlant 17:14, 15 February 2007 (UTC)

The thing to be aware of is that there are two kinds of noise: voltage noise, which dominates in low impedance situations, and current noise, which is more important in high impedance situations. Op-amps that are optimized for low voltage noise usually have high current noise and vice versa. The point is that, if it really is just the voltage noise that you care about, you have to choose your circuit carefully so that current noise does not contribute to your measurement. Commercial vendors often have application notes about this, see for example [4]. --169.230.94.28 17:28, 15 February 2007 (UTC)

One might also consider frequency harmonic distortion or intermodulation noise if the input is a complex spectrum. Techniques for measuring this noise are standard: insert two sine-signals, separated in frequency by a small amount (e.g. 50 and 51 MHz). The amplifier output will mix these signals and generate unwanted sidebands (say, at 49 and 52 MHz, in this case: in general, f1-dF and f2 + dF if I recall). On a spectrum analyzer, the power of these sidebands is frequency noise. You might also worry about phase-noise (or distortion of the frequency of the input); there are many ways to measure that, typically using a network analyzer or spectrum analyzer and zooming close into the frequency peaks. These may be more sophisticated than you should worry about if your op-amp is low-frequency, but sometimes such noise can interfere with final applications in unexpected ways! Nimur 01:20, 16 February 2007 (UTC)

Inference

Is an inference, either... "My house has been been robbed" OR "I think my house will be robbed.."(Based on evidence)?. Thanks... Resaloj 12:24, 14 February 2007 (UTC)

Neither - if you return to your house and find it empty you can infer that it has been robbed.

If you are confused about the meaning of word I'd suggest the language desk.83.100.158.13 13:23, 14 February 2007 (UTC)

Alternatively if you a man with the archetypal striped shirt and mask with a bag labelled loot hanging around your house in the early hours of the morning you might infer that your house is going to be robbed..83.100.158.13 13:26, 14 February 2007 (UTC)

Thanks. Resaloj 13:27, 14 February 2007 (UTC)

See inference. It depends what your "evidence" is. If something is missing, there is an inference that your house has been robbed, but it is not proof, as there is also an inference that you may have mislaid it.--Shantavira 13:30, 14 February 2007 (UTC)

Notifying wikipedians

Hello, I have an offer to improve the template:taxobox. I posted my offer on the discussion page. Should I post an announcement anywhere, to attract more attention? Generally speaking, where does one post announcements to attract attention to specific discussions? Many thanks. Gidip 12:54, 14 February 2007 (UTC)

Hello, you can discuss any issues around wikipedia itself at Wikipedia:Village_pump. Mr.K. (talk) 13:01, 14 February 2007 (UTC)

Thanks. Gidip 13:13, 14 February 2007 (UTC)

There's the 'Tree of life' project - Wikipedia:tree of life - don't forget there and hopefully the message will trickle down to the sub projects eg Wikipedia:Tree_of_life#Overview.83.100.158.13 15:12, 14 February 2007 (UTC)

Force needed to tear plastic

This is about finding what force is needed to tear a transparency apart when putting a certain force with it. What is the relationship between the force needed to tear it apart and the width of the trancparency sheet? I.e, if 29.33 newtons in needed to tear a trancarency with a width of 0.8 cm, what force would be needed to tear 5 cm? Thanks. 152.93.89.28 13:36, 14 February 2007 (UTC)

Material stress and strain (unto breaking) is a complicated subject, especially when elasticity comes into play (as opposed to a brittle object, which breaks suddenly even if it requires a great force to do so). So designing an experiment that measured anything about your transparency accurately is non-trivial. However, in general you should expect the strength of an object to scale linearly with its cross-sectional area. --Tardis 14:34, 14 February 2007 (UTC)

Thanks. The grounds for this question is that we basically got two days to play around with whatever we wanted in the physics/chemistry/biology labs (yay!), but we had to note down some data and draw some conclusions based on what we did, so nothing really serious or accurate was expected of us. The answer is much appreciated, and exactly the one I was looking for. Thanks again. 213.167.126.215 21:08, 14 February 2007 (UTC)

Foxfire, bioluminescence

Is there anybody with experience about foxfire in taiga-type forest? Where I can find rotten wood that glows in the dark? Or mushrooms that glows? I would like to have such to decoration. Are glowing mushrooms sold anywhere? I live in Nordic Country that is quite cold so maybe there is not so much rottening going on, at least i have never seen foxfire. By the way would not it be great if by modern technology somebody would genetically mutate a tree so that it would glow. Then these trees would be planted to streets of towns and no street lights would be needed! 193.167.45.242 15:33, 14 February 2007 (UTC)

Some people have indeed genetically modified plants (and pigs) to glow in the dark. As for buying foxfire, that may be quite difficult, as most are poisonous, and therefore the sale would be controlled, and although Honey fungus is safe to eat, it is a notorious pest, and the neighbours wouldn't be too happy having their gardens overrun by glowing mushrooms! Laïka 16:16, 14 February 2007 (UTC)

Category:Bioluminescent organisms might be of interest to you... -- Scientizzle 17:33, 14 February 2007 (UTC)

And, of course, we have Foxfire (bioluminescence).

Atlant 17:17, 15 February 2007 (UTC)

Alchemy

what r the 3 laws of alchemy

How about:

1. Gold is good.
2. With enough effort anyone can make gold.
3. The more noxious, toxic, and bizarre the concoction, the more likely it is useful in making gold.

Seriously though, alchemy is not a science. I don't think there are any meaningful laws. Though please go read our article on alchemy; it is good. Dragons flight 18:24, 14 February 2007 (UTC)

Oooo i know i know i saw this on Fullmetal Alchemist think they were 1) equal exchange 2) =( 3) darn it i forgot

but check out the link it might have some info there or checkout alchemy Maverick423 18:30, 14 February 2007 (UTC)

acctually if you check out just the alchemy article you will find that real transmutations have already been performed acctually creating gold from lead. so yea if you really want real info check that one out (added) and if you want to know about the laws of alchemy the only place i heard about them are in Fullmetal Alchemist 3 laws are stated right here[5]

Maverick423 18:36, 14 February 2007 (UTC)

Are you confusing with the three usual aims of alchemy - make a universal panacea, affect transmutation of base metal to gold , and find the philosopher's stone.83.100.158.13 20:18, 14 February 2007 (UTC)

acctually that is the proccess of alchemy that i posted. identify the substance, destroy it, recreate it. dont know if those are the laws hes looking for but well its pretty close i think as far as the rules go. but then again they do speak about other stuff in the anime that can be the laws but ... well its a thin line here i guess. Maverick423 20:53, 14 February 2007 (UTC)

How strong is Duac?

Hi there!

Just wondering; I'm using this substance, Duac, on my skin against Acne. It contains 1% Clindamycin, and 5% Benzoyl peroxide. How strong is that? Is it one of the more powerfull substances? Does it totally wipe out all bacteria on my skin, or just a few per cent?

Thanks!

213.64.150.116 20:58, 14 February 2007 (UTC)

Due to the marvels of natural selection and evolution, it is very unlikely that all bacteria would be wiped out, especially without damaging your skin. I think you should have a look at both clindamycin and benzoyl peroxide. − Twas Now ( talk • contribs • e-mail ) 21:26, 14 February 2007 (UTC)

This website seems to suggest it is a mild to moderate treatment, if you suffer from severe acne, or you think Duac is not strong enough, you really should talk to a doctor. Vespine 21:30, 14 February 2007 (UTC)

I've seen 10% benzoyl peroxide cream available OTC. The benzoyl peroxide page has some interesting information about the advantages (or lack thereof) of different strength preparations for treatment of acne and also how it works (not really an antibiotic). I wonder if high-strength benzoyl peroxide could interfere with or destroy the clindamycin in a combined treatment? Combination treatments, such as Duac, are usually a balance of components, not maximum-strength of all. DMacks 01:24, 15 February 2007 (UTC)