Science desk
< February 9	<< Jan \| February \| Mar >>	February 11 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an 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 10[edit]

copper sulfate and potassium hydroxide[edit]

what happens when you add copper sulfate and potassium hydroxide together, and why it produces the result? —Preceding unsigned comment added by 220.238.205.237 (talk) 04:14, 10 February 2008 (UTC)[reply]

This question reeks of homework. Do it yourself, or if you really need to, enter your question into Google like I did and read the answer. I'm often surprised by people who take the time to ask things here, and wait, when they could get the answer themselves in about 60 seconds if they'd try. Pretty weak... dw —Preceding unsigned comment added by 24.86.250.218 (talk) 07:35, 10 February 2008 (UTC)[reply]

Assume good faith. Thanks. Wisdom89 (talk) 07:48, 10 February 2008 (UTC)[reply]

If this is a homework question, then there are very few things you'll have to ask yourself in order to answer it. The first one is, will anything present react with anything else? Potassium doesn't react with sulfate or copper, so what about the other two combinations? Nope. If there's not going to be a reaction, then your teacher is obviously asking whether anything will precipitate out of the solution. In other words, what combination of ions isn't soluble, if any? If you have trouble figuring that out, it's better to tell us why, instead of just asking for the answer. That way we can teach you how to find the answer. ;-) Someguy1221 (talk) 11:49, 10 February 2008 (UTC)[reply]

Wait...I thought the formation of a precipitate was a reaction? --Emery (talk) 21:45, 10 February 2008 (UTC)[reply]

I don't consider it a chemical reaction since there is, formally, no explicit chemical change. Someguy1221 (talk) 00:17, 11 February 2008 (UTC)[reply]

I would have guessed a possible product would have been potassium sulfate - obviously the KOH would dissociate - although K2SO4 is insoluble in basic solutions. Wisdom89 (talk) 21:51, 10 February 2008 (UTC)[reply]

Ah, but will the solution still be as basic when all is said and done? Copper can syphon off that hydroxide pretty effectively. Someguy1221 (talk) 00:21, 11 February 2008 (UTC)[reply]

DNA replication[edit]

I realize this probably requires a lot of education to understand, but I was hoping for a summary. I know all the steps of DNA replication that I have read from various overview sites: helicase splits DNA; RNA primase inserts starter nucleotides; DNA polymerase adds complementary DNA nucleotides; ... a lot of gap filling ... and viola, a copy of DNA. My questions are: where do these various helpers (helicase, RNA primase, DNA polymerase, exonuclease, ligase) come from? Are they just sitting around waiting for their turn? What is telling them when to move into action? How does step 2 know when step 1 is done, and so on? Are there any links to better overviews of this? Thanks! — BRIAN0918 • 2008-02-10 05:42Z

Like many processes ocurring in the cell DNA replication is basically the result of chaos. The right enzyme just happens to be at it's required position at the right time. It might feel a bit odd a first, but when you realise that there are countless copies of each of these enzymes present within the cell it al starts to make sense. They don't " know " the order in which they work either. It's simply impossible of the enzymes you listed to do their jobs before the other one has finished (or at least started working). So in other words, yes they are just hanging around ...well bouncing around the inside of your cell nucleus untill they can do their job. PvT (talk) 11:11, 10 February 2008 (UTC)[reply]

At all times during a cell's life (except right after replication starts) there is protein complex called the origin recognition complex that is bound to the replication origins. These not only bind to DNA, but also to helicase and a couple other protiens. Once parts of the complex have been phosphorylated by the appropriate kinases (which are activated by cell-division promoting factors) the helicases are directed by the complex to open the DNA. Primase then binds to helicase and adds primers where there is room. Then uh, yeah, topoisomerase and DNA polymerase come in somewhere...Since many of the ligases and polymerases (as well as helicase) are involved in DNA repair, it's likely at least some of the machinery is around all the time (not that it's not known, merely that I don't know). Anything that isn't would likely have its genes activated around the same time as the origin binding proteins. I have a textbook I could email you that contains as detailed a description as I've ever seen of replication, and it may answer your questions. Drop me an email and I'll send it to you, assuming you can handle a 90mb attachment (and me, as well, as I've never tried sending anything that big). Someguy1221 (talk) 11:41, 10 February 2008 (UTC)[reply]

fuzzy control of dc to dc converter[edit]

In the implementation of a fuzzy controller of a dc to dc converter it is found that the input variables to the fuzzification level are the values of the error(difference between the output voltage of the converter and a reference voltage) and the change in error(difference between the error at k^th instant and the error at the (k+1)^th instant. I need to know why this is so. Also the error range was between -1.0 and 1.0. Why? I will provide here the link to the ieee paper that contained this article : ieeexplore.ieee.org/iel3/41/13741/00633467.pdf Please also mention how the hardware implementation of the paper is to be done. I am in urgent need of an answer since I have a review exam in college tomorrow. I will be grateful to you. Thank you for the help. —Preceding unsigned comment added by 59.89.20.119 (talk) 14:08, 10 February 2008 (UTC)[reply]

Sassafras wood - safe to burn in fireplace?[edit]

A friend told me that the fumes from sassafras wood are toxic when burned in a fireplace. Neither Google nor Wikipedia confirms this, although a product of the tree taken internally is forbidden by the FDA. —Preceding unsigned comment added by 24.127.124.38 (talk) 15:37, 10 February 2008 (UTC)[reply]

Hi. I'm not sure about your actual question, but I heard that sassafras was banned in coca-cola because a cancer-causing agent was found in it. However, I think you should wait for a more detailed answer. By the way, coca-cola used to have coca and kola. Hope this helps. Thanks. ~A H 1^(TCU) 16:24, 10 February 2008 (UTC)[reply]

Safrole is the toxic element in Sassafrass. This is skirting the edges of Wikipedia's ban on medical advice, but I would think that fumes of any burning wood are toxic, if only because of the carbon monoxide released. A properly-functioning fireplace should be able to safely burn pretty much any wood. --Mdwyer (talk) 23:38, 11 February 2008 (UTC)[reply]

Pure nucleic acid[edit]

Is it possible to extract pure DNA/RNA, and if yes, what properties does it have? I presume it displays all properties common to acids, but more specifically: is it a liquid? What color, viscosity, etc.? - Sikon (talk) 15:58, 10 February 2008 (UTC)[reply]

It is certainly possible and is done routinely in molecular biology labs. I believe pure, dry DNA is a white solid. Thinking of it as an acid may be thorwing you off a little. DNA and RNA have more in common with other polymers than they do with acids you are more familiar with. ike9898 (talk) 16:13, 10 February 2008 (UTC)[reply]

(Ec) It depends on whether the DNA is in solution or precipitated, and how long the strands are. (A solution containing plasmids a few thousand bases in length is going to have a much lower viscosity than one containing strands of genomic DNA millions of bases long.) DNA alone is a white solid—not a liquid. Extraction and isolation of DNA is very easy; if you'd like to prepare a crude DNA extract you can actually do it in your kitchen. This link has instructions and photographs.

DNA and RNA are routinely isolated in the laboratory. The classic method is phenol-chloroform extraction followed by ethanol precipitation, but there are a number of other techniques in our article on DNA extraction. Google is your friend here— search on keywords like DNA extraction protocol or RNA extraction protocol and you'll get dozens of relevant hits. TenOfAllTrades(talk) 16:19, 10 February 2008 (UTC)[reply]

All of the above comments are absolutely correct - However, just one note, any DNA/RNA that you purify, whether it be plasmid DNA, genomic DNA or the various RNAs, will be contaminated with protein. There are methods routinely employed in laboratories to extract the purest and highest grade nucleic acid possible, but it's never 100% efficient - even with commercial kits available. As for the properties, well, the nucleic acids tend to like slightly alkaline conditions and dissolve somewhat readily in such solutions. In solution, plasmids adopt several different physical conformations, genomic DNA is a mess, seriously, and RNA tends to form secondary structures (since it's predominately single stranded). Wisdom89 (talk) 18:00, 10 February 2008 (UTC)[reply]

A popular home DNA purification is that of banana (see this). It uses easily obtainable products, and you should be able to substitute isopropanol (rubbing alcohol) for the 95% ethanol. -- Flyguy649 ^talk 22:55, 10 February 2008 (UTC)[reply]

Please help me understand some "cookbook" chemistry[edit]

I have a procedure that I follow like a recipe, but I would like to better understand what is actually going on. The procedure involves using performic acid to oxidize a sample; this part I understand. When the oxidation is complete, I add hydrobromic acid to the solution and it turns bright orange. This is the part I want to understand. I don't really care why it turns orange, but I do want to understand what the HBr is doing. Is it somehow 'stopping' the reaction? After this step, I remove all the reagents by rotovap. Is the step in question somehow making the reagents volatile so they can be easily removed? ike9898 (talk) 16:09, 10 February 2008 (UTC)[reply]

Yes, the hydrobromic acid reacts with – and thereby inactivates – the performic acid to stop the reaction. (I'm not certain what the products of that reaction are, but I suspect they're all volatile: formic acid, water, bromine.) As you suggest, excess hydrobromic acid will evaporate completely, as it's just a solution of (volatile) hydrogen bromide gas in water. TenOfAllTrades(talk) 16:38, 10 February 2008 (UTC)[reply]

Jellyfish[edit]

Hi. See my question on Talk:Jellyfish#Invasion. I want to see the article if there is one on nemoura but I din't know the spelling. These jellyfish are invading off the coast of Japan and damaging the fishing industry. Thanks. ~A H 1^(TCU) 16:30, 10 February 2008 (UTC)[reply]

I think you might be looking for Nomura's jellyfish. TenOfAllTrades(talk) 16:40, 10 February 2008 (UTC)[reply]

Viviparous (common) lizard[edit]

Here's a poser for someone who knows about lizards:

Last night, after dark, I met some friends in Staffordshire, UK, and we spotted a Viviparous lizard on the concrete path. It's about 1½" (4cm) long. It had presumably been basking, as it had been a sunny day, but as a heavy frost was forecast, we thought it was probably at risk where it was, so we rescued it. It is now in my kitchen (right), in a bowl with some water, moss and some leaves. It seems perfectly happy, but I'd welcome some advice on the best way to look after it, and where and when to release it. The weather in Britain at the moment seems to be relatively warm during the day, but more frosts at night. Anyone have any knowledge of this sort of thing? Tivedshambo (talk) 21:21, 10 February 2008 (UTC)[reply]

I suggest you put it back. They are very hardy and will be more bothered by a plastic bowl and lack of insects than a spot of frost.--Shantavira|^{feed me} 08:28, 11 February 2008 (UTC)[reply]

That's a nice picture. I don't have any answers for you - but would it be okay to use your photo in the Viviparous lizard article? --Kurt Shaped Box (talk) 08:58, 11 February 2008 (UTC)[reply]

Are you sure it is a viviparous lizard?! It sure doesn't look like one to me. Looks more like a smooth / common newt actually (see, for example, this page ). Please anyone knowledgeable in British fauna clarify this one! Kindest wishes, --Dr Dima (talk) 10:25, 11 February 2008 (UTC)[reply]

I'm pretty certain it's reptilian, not amphibian. The skin was too dry, and amphibians don't tend to bask as the skin dries out (thanks to David Attenborough on TV last night for teaching me that!). I'll release it back into the wild as the do seem to be more hardy than I'd suspected - it just came as a surprise finding one in February. A sign of climate change perhaps. Feel free to use the picture - that's what it's there for! Tivedshambo (talk) 12:36, 11 February 2008 (UTC)[reply]

Viviparous lizard has very clearly visible scales covering its body (see, for example, this page ). The photograph you provided is quite high-res, yet I can't see any scales. Bottom line: I think it's a newt. --Dr Dima (talk) 14:51, 11 February 2008 (UTC)[reply]

You may be right - I'll tag the photo to state this. Either way, it is now back in the wild. Tivedshambo (talk) 07:42, 12 February 2008 (UTC)[reply]

Another year on for this discussion but it is absolutely a Newt not a lizard - I have both in my garden. Whether you could say it is a Smooth newt is more difficult because it is very early for newts to be taking on their mating colours and form. For what it is worth we have Palmate newts occasionally active in February further north than Staffordshire (but yours isn't Palmate). Velela (talk) 13:22, 5 March 2009 (UTC)[reply]

colon cancer[edit]

Who first discovered colon cancer?Jafra girl (talk) 21:55, 10 February 2008 (UTC)[reply]

Cancer itself has been known since antiquity, though not by that name until Hippocrates and Celsus. The Wikipedia article on cancer says "The first known surgical treatment for cancer was described in the 1020s by Avicenna (Ibn Sina) in The Canon of Medicine." This probably involved the removal of an external, visible tumor, since surgery as we know it only came in during the late 19th century with the advent of anesthesia and infection control. An early anatomist who conducted human dissection and autopsies was Ibn Zuhr (Avenzoar), working in Spain in the 12th century. We can suppose he might have seen colon cancer, it being not uncommon, but no occidental, if you will, before him dissected human remains. You have no doubt noticed that I haven't simply provided a name; that's because I don't know, but whoever it was didn't so much "discover" it as "describe" it medically. People have known about cancer all along. --Milkbreath (talk) 12:21, 11 February 2008 (UTC)[reply]

Orkney Isands[edit]

What is the scientific origin of the Orkney Islands, and what kind of islands are they? 96.244.11.56 (talk) 22:42, 10 February 2008 (UTC)Lea Jackson[reply]

List of islands of Scotland has some info. They're on Old Red Sandstone. AlmostReadytoFly (talk) 12:54, 13 February 2008 (UTC)[reply]