Wikipedia:Reference desk/Archives/Science/2012 October 13

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October 13

Yagi-Uda antenna for wlan

Are they possible? Difficult to implement? Expensive? How big? OsmanRF34 (talk) 00:02, 13 October 2012 (UTC)

Yes. No. No. Small. Zoonoses (talk) 03:23, 13 October 2012 (UTC)

• I'm no expert, but a little searching provided some references that address your questions: [1][2] [3] -- Scray (talk) 12:12, 13 October 2012 (UTC)

Physical process at work when airing out some smokey clothes?

I went to a social event last night that featured a great deal of smoking. Not a smoker, I was annoyed that my suit reeked of cigarettes when I got home. Without giving it much consideration, I hung my suit outside to "air out" overnight. Then I realized I have no idea what is literally happening during this process, meanwhile the outcome is assumed. What happens to the cigarette scent? The particulates don't just magically jump off my suit, do they? Why does it freshen? The Masked Booby (talk) 01:08, 13 October 2012 (UTC)

Liquid components can evaporate, solids can either sublimate or be blown off. UV light from the sun may also cause chemical reactions, and other scents (like in pollen) may be deposited on the clothes and then disguise the smoke smell.StuRat (talk) 01:14, 13 October 2012 (UTC)

The word you are looking for is adsorption, the process by which gases and liquids come to cling to surfaces. There is a thermodynamic equilibrium between adsorption sites and adsorbents in the air. In smoky air, the amount attached to clothing will increase until the adsorption sites are more or less saturated. In clean air, the adsorption sites will slowly and spontaneously release the molecules they have been holding. This causes a lingering odor even after the clothing is removed from the smoky environment. The odor dissipates once all the attached molecules have released from the clothing and had a chance to drift away. When possible, washing the clothing is also generally effective at removing adsorbed odors. Dragons flight (talk) 05:06, 13 October 2012 (UTC)

Also notice that the reason to hang it outside isn't just to deodorize it, but also to prevent the odor from being deposited on other objects inside.StuRat (talk) 06:30, 13 October 2012 (UTC)

Why inorganic and + (plus sign)

I am confused why we classify CO and CO² as inorganic compound even when both contain carbon. My another question is - While reading newspapers I always see + {sign} and some small colorful circles at the bottom of each page, where there is no text. I think these + and small circles have some importance, but I don't know what is that importance. Sunny Singh (DAV) (talk) 09:02, 13 October 2012 (UTC)

Both CO (carbon monoxide) and CO₂ (carbon dioxide) are commonly created by inorganic processes, such as volcanism.StuRat (talk) 09:35, 13 October 2012 (UTC)

CO₂ is also commonly created by organic processes, such as eukaryotic respiration. If you have a room full of chemical scientists, you'll be assured to have more definitions of the term organic than there are people in the room. Plasmic Physics (talk) 12:12, 13 October 2012 (UTC)

Personally, I prefer to define "organic molecules" as a molecule that contains both hydrogen and carbon, without exception. Plasmic Physics (talk) 12:15, 13 October 2012 (UTC)

That's probably too rigid. I don't think that any chemist I know would classify Mirex as "inorganic", and certainly PTFE would be counted as organic as well, despite not having any hydrogens. - As Graeme points out below, the reason for the organic/inorganic split is the initial belief invitalism, where the distinction between organic and inorganic wasn't based on atom composition, but on the (erroneous) belief that the materials that made up life had some "élan vital" that made them different from inorganic ones. The "contains carbon" was a post-hoc rationalization for the split. - Personally, my definition of "organic" is more along the lines of "contains carbon, except for a few historical exceptions". The "contains both hydrogen and carbon" might be okay if you altered it to "contains either carbon-hydrogen or carbon-carbon bonds". (As Plasmic Physics says: more definitions than people in the room). -- 205.175.124.30 (talk) 21:14, 13 October 2012 (UTC)

I know it's just an opinion, but based on vitalism, it seems silly that as a synthetic polymer applied to frying pans, PTFE is considered organic by most chemists. Likewise, Mirex just doesn't exactly scream organic either. Plasmic Physics (talk) 00:02, 14 October 2012 (UTC)

question two Printing registration --Digrpat (talk) 09:30, 13 October 2012 (UTC)

I added a title, but what is the question ? StuRat (talk) 09:34, 13 October 2012 (UTC)

I removed your heading, StuRat. Digrpat was answering the second question asked by Sunny Singh— the "+ {sign} and some small colorful circles" are registration marks. Deor (talk) 10:14, 13 October 2012 (UTC)

OK, thanks, I thought it was a new, misplaced Q. StuRat (talk) 10:24, 13 October 2012 (UTC)

The organic substances were originally though to be made only by living things, and there were other carbon containing moleculed like hydrogen cyanide or ammonium carbonate or calcium carbide that were classed as inorganic too. Eventually people figured out how to make organicurea and the distinction was blurred. Graeme Bartlett (talk) 12:14, 13 October 2012 (UTC)

• I've seen various arbitrary definitions of organic compounds, such as "anything with carbon" or "anything with carbon and hydrogen". It looks like the definition can be different in practice, as I infer from [4], which defines volatileorganic compounds as being, well, volatile, and "any compound of carbon, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonate." I note that this excludes C, CO, CO2, H2CO3, Na2C2, Na2CO3, (NH4)2CO3. So the EPA is excluding even some things with hydrogen, so long as it has an "ionic" character to it, or is part of an ion; but they're not excluding, say, carbon tetrachloride orCFCs without hydrogen. So it's apparently a ... flexible ... definition. Wnt (talk) 20:27, 15 October 2012 (UTC)

Visual imagination of birth-blind people

Redirect me if this question was asked earlier, but can birth-blind people approximately imagine their daily surroundings, such as apartment they live in? Also, how much correct is a blind person's imagination, can (s)he describe for example a beautiful woman based on clues of his/her life experience?--176.241.247.17 (talk) 09:05, 13 October 2012 (UTC)

People who are congenitally blind have special skills in mentally-mapping spatial relationships they determine by feel PMID 17368576 and PMID 8124943, but some imagery functions are impaired PMID 11496156 and they don't construct detailed visual mental images in the same way that sighted people do (which can be a hindrance or an advantage, depending on the situation) PMID 16556565. "Beautiful", of course, is at least as much cultural as it is biological. -- Scray (talk) 11:48, 13 October 2012 (UTC)

Getting an oversized Disk though a circular hole in a bendable material ....

If you have a solid disk (eg like a CD) and you want to get it through a circular hole (eg to get it into a sealed plastic bag) (The plastic is bendable but not stretchable, the disk is rigid) you dont have to have the hole diameter as large as the disk. I know I have tried it.

If you bend the plastic along the diameter of the hole and flex it you can pass through through the hole the larger size diameter disk.

If the whole was infinitely 'flexible' (like a circular piece of string) it could be pulled to make a slit; then, if the circular hole had diameter 'd', clearly the disk could be oversized to a diameter d x pi/2 (approx 1.5d).

But the paper or plastic cannot be moved to give a slit shape... Probably the maximum opening depends upon the 'flexibility of the material with the hole cut into it...

... is there any maths of written in for on this!!??

(The problem has practical purpose as I want to get a flange through a hole into a sealed plastic gas collection bag, link this internal flange to an external flange fitted with a tube to give a gas tight seal - to get a tube for my gas collection bag to get it fit for purpose!)

Thanks email redacted — Preceding unsigned comment added by78.145.76.1 (talk) 11:08, 13 October 2012 (UTC)

If the opening of the container is flexible, then we could think about the problem as the circumference of the cross-section of the curved disc (you describe it as rigid, but it can be flexed), which would have as upper bound the cross-section of the flat disc (if d is diameter of the disc and x is the thickness, it would be 2d+2x, but x << d so it's approximately 2d). Curving the disc will, conceptually, shorten one side. Assuming that the disc cannot be curled to overlap, the minimum would be d (with the disc curled around to make a cylinder; obviously, the latter isn't easy with a CD). So, I think the opening needed is bounded by d..~2d, and depends on the flexibility of the disc. -- Scray (talk) 11:35, 13 October 2012 (UTC) Heron is correct in following comment - I reversed the problem. -- Scray (talk) 03:19, 14 October 2012 (UTC)

Scray, I think you are confusing the flexible plastic of the bag with the rigid plastic of the disc. The disc is rigid. The only reason OP can't stretch the hole into an arbitrarily narrow slit is that the material has a finite Young's modulus that resists bending. If the material were perfectly flexible but inelastic, like very fine chain mail, then you could perform the feat. It only seems impossible because the force required increases to infinity as you approach the ideal slit shape - a bit like trying to straighten a clothes line by pulling on the ends. Maths can help you only by telling you how much force it would take to deform the sheet to a given slit shape. --Heron (talk) 15:40, 13 October 2012 (UTC)

Quite right - sorry. -- Scray (talk) 03:19, 14 October 2012 (UTC)

The material has to be stretchable to some degree for that to work. If it isn't stretchable at all, the only thing you can do with it is fold it, and that isn't helpful. Looie496 (talk) 15:28, 13 October 2012 (UTC) Gah, what was I thinking?Looie496 (talk) 02:59, 14 October 2012 (UTC)

Agreed, given the constraints of a disk that wont bend at all and plastic that won't stretch at all, the slit in the plastic would need to be as wide as the disk. As far as getting a gas-tight seal, you could try a resealable bag. Those aren't quite a perfect seal, so you might need to add some tape around the edges and corners. You could also use shrink-fit plastic, which shrinks when heated with a blow-dryer. But, again, you may need to use tape to seal up any leaks. And, of course, plastic bags won't hold much pressure, in any case, and will slowly leak small molecules, no matter how well sealed they are. StuRat (talk) 20:54, 13 October 2012 (UTC)

Hmmm, I'm not absolutely sure that you couldn't expand the slit at all at one point by some deformation of the plastic around the hole that did not involve stretching. That sounds like a non-trivial math problem to me... Wnt (talk) 23:44, 13 October 2012 (UTC)

Perhaps there's some difference in how we are using the term "stretching". All materials can undergo both elastic and plastic deformation, to some degree, except for a theoretically "perfectly rigid solid" (these don't exist in real life, but crystals come close). Elastic deformation is when a material deforms and then returns to it's original shape. Plastic deformation is when a material deforms but does not return to it's original shape. As the name implies, soft (thermo)plastics tend to have great deal of plastic deformation, but still do have some elastic deformation. I am calling both types of deformation "stretching". Perhaps the OP is not including elastic deformation. In this case, it would be possible to elastically deform some plastics enough to allow a CD to be inserted, and then have the slit reduce back down to the original size. If you make the bag out of an elastic material, you could use a much smaller slit. StuRat (talk) 00:12, 14 October 2012 (UTC)

Turret milling machine or Universal milling machine..?

Hi I am going to start a new workshop and want to buy milling machine but I want to know which machine will be suitable for me turret milling machine or universal milling machine. My use of machine will be producing flat surface on small jobs of normally 100 X 200 mm. — Preceding unsigned comment added by 14.140.235.82(talk) 14:02, 13 October 2012 (UTC)

What will best suit your needs depends on a multitude of factors that we cannot know. Budget? Is this for a new hobby or some sort of small business? What are you going to machine - mild steel, aluminium, special alloys? Plastic? To what accuracy? Do you intend to machine something occaisonally or all day long every day? One would guess from the question that you are a beginner/hobbyist. As such, rather than ask us, a better approach would be to get hold of one or two good trades or hobby level books on machine metal working. Even better, subscribe to journals such asModel Engineer's Workshop for a year or so - you'll learn a lot. Then, join a local hobby engineering group or make contact with an interested tradesman, perhaps someone retired. You question is the sort best dicussed at length with a knowledgable person face to face rather than posting a question to an internet forum. If the highest accuracy is not required, and you only want to do this occaisonally, a better first purchase would be a good pedestal drill. You can fit a low cost X-Y table and milling cutters on a pedestal drill and do quite usefull work at the fraction of the cost of a proper milling machine. However, if your ultimate aim is certainly to end up doing work of professional standard, you should select a machine on the basis of easy upgrade to CNC. Don't forget also, that flat surfaces can be done quickly and very satisfactorily on a lathe, and a lathe can do a lot that a milling machine cannot do. Thats's why there's a lot more hobbyists and small shops that own a lathe as their only machining tool than there are hobbyists and shops that own a milling machine. Are you going to work in plasic, or can the things you want to make be done in plastic? If so, 3D printing is now the way to go. Ratbone60.228.235.209 (talk) 15:24, 13 October 2012 (UTC)

For that matter, if you only want to make a flat surface in metals such as steel, aluminium, brass, once in a while, say once each few months or more, and you have a good degree of patience, you don't need any powered machine tool at all. The hand method suitable for a job 100 x 200 mm is as follows:-

1. Cut to a slight oversize as best you can with a hacksaw - use a new blade and take it with nice and slow long strokes without forcing it. You should get to within 0.5 to 1 mm of true.

2. Use a coarse double cut barstard file (steel) or dreadnought file (aluminium or brass) to bring the surface to within 0.1 to 0.15 mm, checking with a steel rule. People who have not been properly trained in filling find it difficult not to produce a curved surface - clamping a piece of 30 x 30 square steel tubing to the backside of the file helps - put some shims between the file and the tubing to convex the file surface slightly to compensate for the natural human tendency to curve the work surface the other way. If you find it hard not to curve the work you are probably applying too much force or you have the workpiece to high or too low for you. Finish up by drawfilling with a single cut mill file, being carefull to only "load" the file with fingers over the middle of the workpiece.

3. If greater flatness than +,- 0.1 mm is required, get a piece of float glass to use as a reference surface. Use a can of spaycan paint to apply a THIN coat to one side of the glass. Don't wait for it to dry. Rub the painted surface LIGHTLY on to the work surface. You'll now have paint on the high spots of your work surface. Now, use a hand scraper to scrape metal only where there is paint. Repeat as necessary until the paint evenly coats the work. The professional version of this is to paint the work with marking blue or a felt tip pen and then rub it with a reference flat surface, and scrape where there blue or felt tip has been rubbed off.

With care and patience, you can make a surface flat to an accuracy exceeding that of the best machines with this method. But you WILL need patience. When you feel yourself getting bored and tending to force the tools, take a break. See http://en.wikipedia.org/wiki/Hand_scraper. Ratbone121.221.218.240 (talk) 11:24, 14 October 2012 (UTC)

An important question is whether or not the OP needs his flat surface to be parallel to, at right angles to, or at some specified angle to, another flat surface on the workpiece. Right angles can be done accurately on the lathe with some care and a dial probe. Right and arbitary angles can be done easily on a turret milling machine. They can only be done by hand scraping if both a reference flat surface and a reference angle block is avalailable. Reference blocks are readily available for right angles but not arbitary angles. Floda124.178.37.144 (talk) 02:58, 15 October 2012 (UTC)

Europa from Io

Having read the articles about Extraterrestrial skies and Apparent retrograde motion, here's what I'm wondering: What would Europa's path look like for an observer sitting at Io's antijovian point? It will return to the same position after two Ionian days, and there will be some sort of retrograde motion, but apart from that, I can't really visualize it.

Many thanks :) JaneStillman (talk) 14:25, 13 October 2012 (UTC)

Retrograde motion only appears when you look at something closer to the center than you are -- not the case here. The motion is quite simple. Let's start with the two moons aligned: Europa appears then at the zenith. For about a day, Europa drops toward the horizon. For about two days it is absent. Then it appears on the opposite horizon, and takes another day to climb back to the zenith. (The motion of Io as seen from Europa is much more complicated.) Looie496 (talk) 15:41, 13 October 2012 (UTC)

Actually, as I think about it, the apparent motion of Io as seen from Europa is not complicated either. You simply see it revolving around the central planet which remains fixed in the sky -- the apparent speed of revolution is exactly half of the true speed. Looie496 (talk) 17:09, 13 October 2012 (UTC)

Could you clarify what you mean by "Retrograde motion only appears when you look at something closer to the center than you are", Looie. It's the planets that are farther from the Sun than Earth that appear to have periods of retrograde motion (from our perspective); Mercury and Venus don't.Deor (talk) 22:30, 13 October 2012 (UTC)

Yes they do — when they're on our side of the Sun. —Tamfang (talk) 05:26, 14 October 2012 (UTC)

My simulation gives a curve resembling a cardioid, with a small loop in place of the cusp. —Tamfang (talk) 05:26, 14 October 2012 (UTC)

I have to admit that the answer I gave was wrong, because I forgot about the fact that "retrograde" is defined with respect to the stars. On an ordinary satellite that's the only reasonable way to define it, but on a tidally locked satellite like Io or Europa it's a little strange. The fact is, as I said, that if you stand on Io and watch Europa, you will see it steadily rise in the sky and steadily fall, without ever reversing direction. But at the same time the stars also rise and fall. Most of the time Europa is rising or falling faster than the stars, but there is, I should have realized, a short period of time while Europa is near the zenith when the stars outpace it. And that, by the usual definition, is retrograde motion.Looie496 (talk) 14:56, 14 October 2012 (UTC)

Atomicity of elements

I want to know about elements in which more than 4 atoms combine to form molecules in elemental state apart from the following:

• 4- n,p,as,sb
• 6- carbon(benzene ring)
• 8- S,Se,Te
• 12-Boron
• 60 and higher fullerene

And is it true that osmium is octa-atomic and ditungsten and dimolybdenum is possible with sextuple bond

• Thanks in advanceSolomon7968 (talk) 17:01, 13 October 2012 (UTC)

• Well, we actually have a sextuple bond article, and it's totally news to me. The diagram in the article makes it look like 5 d orbitals and one s orbital are involved. Searching for "sd5 hybridization" and molybdenum turned up [5], which says it is found in HC(triple bond)MoH3; but I've never heard of sp3 hybridized carbon, say, using all four bonds to interact in a two-atom molecule ... but that's not really quite the same. Hmmm. It should be very interesting to hear a serious inorganic chemist comment on this one. Wnt (talk) 20:26, 13 October 2012 (UTC)
• I'm thinking your list of molecules may be hard to define. For example, grab a lump of elemental metal, any metal, in vacuum. Ta-da, instant "molecule", with a bazillion atoms "bound together" to some degree or other. One can argue that fullerenes fall, very loosely, into this category.
• Also, I'm not really aware of a [C=C=C=C=C=C=] ring (benzene contains hydrogen, of course). Diamonds are another type of very very large molecule. Wnt (talk) 20:30, 13 October 2012 (UTC)

Could you clarify the question, i.e. criteria for inclusion? For example, do you include Boron as you do because of Cs₂B₁₂H₁₂? If so, that's not really in elemental form, right? Same goes for benzene, as Wnt asks. If you include these, then do all of the atoms of the same element need to be contiguous? I find the "elemental" version of the question interesting, but then the list you gave must be edited. -- Scray (talk) 20:41, 13 October 2012 (UTC)

Also, do they have to be neutral? If you type "boron clusters" into NCBI you'll get a lot of references; some discuss anions, however. See[6] and [7] for example. I get the feeling (not sure though) that you can pretty much blast boron into any size fragment you like; I suppose this is true of most elements, unless smaller compounds (like N2) are strongly preferred. Wnt (talk) 20:45, 13 October 2012 (UTC)

Do they have to be stable, or do you also consider at high pressure or other special conditions, high-energy states, and short-lived species? Nature is crazy...she gives us tetraoxygen and octaoxygen. DMacks (talk) 21:32, 13 October 2012 (UTC)

If you allow charge you can get Hydrogen ion clusters and Pentazenium. Also there are octaoxygen, tetraoxygen and fullerenes with less than 60 atoms and no charge. Sulfur can form all sorts of ring sizes apart from 8. Graeme Bartlett (talk) 21:42, 13 October 2012 (UTC)

With charge Pentazenium and others are radicals which I am not considering and my version of boron is boron allotrope gamma boron. I am not considering clusters inside compounds but have considered benzene ring because it can be considered a structural unit of graphene andgraphite. Thanks for mentioning tetraoxygen and octaoxygen and please mention other exotic ones.Solomon7968 (talk) 13:58, 14 October 2012 (UTC)

• You may be interested in the Allotropes of sulfur, for example Octasulfur (S₈) -- LukeSurl ^{t c} 15:25, 14 October 2012 (UTC)

"The current price per package of tasonermin (Beromun 4 vials 1 mg) is EUR11,813.54. "

Come on! How can 4 mg cost that much? If they are protected by patents, is there a black market somewhere for this? It seems economically more attractive to produce such kind of things, being at 2.5 millions/gram than any other illegal drug. OsmanRF34 (talk) 22:33, 13 October 2012 (UTC)

Monopoly prices are absolutely arbitrary. (For a shining example of contemporary medical ethics, see Colcrys.) Nonetheless, four milligrams of highly purified, active human protein is not something that is really that easy to cook up in a lab. Note that a specific protein, unlike cocaine, isn't something that you can mix up with gasoline and salt and shake out of solution - you have to baby it through the isolation process to avoidprotein denaturation. A misfolded protein wouldn't work - I'm guessing it might even trigger some damaging autoimmune response. I'm not that well versed in business to pull out the commercial details from the company, but my feeling is that if you got a graduate student to whip something up in a week in a basement laboratory, it would cost a substantial fraction of the price, and many bad things could happen.

That said, I can picture alternatives and workarounds. Notably, TNF-alpha can be induced by things like gram (-) endotoxin[8], which is undoubtedly vastly cheaper and more available, though that of course can (will) induce other cytokines in a different pattern than the purified cytokine. From [9] note also that diet affects TNF-alpha production - more omega-3 fatty acids lead to less production in blisters. (I suspect that "dry" cupping therapy is a practice which will be reexamined in the near future, for this and some other reasons e.g. thymosin - the fluid produced by blisters is a who's who of potentially therapeutic proteins, though in other cases they are undesirable. Maybe that's nuts, but then again, I was the only person I knew in the 90s who was soft on Lamarckism :) ) But there are many, many ways to get TNF-alpha production to increase, and I probably haven't thought of the best here. My guess, in short, is that a black market in purified TNF-alpha is not very feasible. Wnt (talk) 23:24, 13 October 2012 (UTC)

That sounds about right, actually. If I want to buy 4 mg of recombinant human TNF for the lab tomorrow, that'll cost me £7200 from Peprotech (my usual cytokine supplier). And that's research quality, which didn't need to be qualified for clinical use. In this case, there isn't even a patent on it, although there probably is one on tasonermin specifically with regards to formulation etc etc. Recombinant proteins are expensive any way you look at it. As for using something else to increase endogenous TNF production, good luck in finding something that specifically upregulates TNF production without changing any other cytokine levels. (Hint: don't bother, it doesn't exist) Fgf10 (talk) 08:56, 14 October 2012 (UTC)

OK, but along the production line, where does the money goes to? In this case, no patent, as stated above, so? Machines? Technical personal? Long cooking process? Necessary extraction from humans? OsmanRF34 (talk) 21:41, 14 October 2012 (UTC)

Ooh, now that's tricky question! First off, it's not extracted from humans (haven't checked this specific one, but in general). These sort of things are made by inserting the human TNF gene in a bacterium or yeast, which is then grown in massive bioreactors. It won't be a very labour intensive process, so that probably won't be the main expense. The consumables for purifying the protein from the bioreactor will be a big chuck of the cost. The thing to remember as well is that 4 mg might seem like next to nothing, but in the world of recombinant proteins, it's an absolutely massive amount. For research use, your normal order would be in the order of 10 to 100 ug.

Of course overhead and near-monopoly pricing has a lot to do with the final price as well. To be honest, I doubt anybody who doesn't work for a biotech company who makes stuff like this can give a sensible answer here (and they wouldn't of course. I will note however, that prices (outside clinical use at least) are flexible, for instance, the £7200 I quoted further up is the list price, for such a bulk order I would expect to actually pay between a quarter or half of that price. Sorry for not being able to give a more conclusive answer. Fgf10 (talk) 07:15, 15 October 2012 (UTC)

Agreed. Another component of the pharmaceutical price has to be maintenance of a liability fund - litigation with biologics is pretty common and expensive in some markets. You mentioned the costs of production for clinical use: GMP. -- Scray(talk) 08:56, 15 October 2012 (UTC)

I should revise my statement above to some degree - it might be a bit more feasible... also less so. The similarity in price between lab TNF and the pharmaceutical seemed suspicious ... looking up the Beromun tasonermin, I find that it is actually a non-glycosylated recombinant protein from E. coli, a trimer of three peptides - it's not being produced in the fancy way that nature does it, i.e. TNF that's been inserted into the membrane, covalently modified, and chopped free by an enzyme.[10] It turns out that the human TNF doesn't actually have any glycosylation site. [11] Being grown in bacteria makes it cheaper, and potentially easier to pirate than I'd thought, though still by no means easy. The amino acid sequence used matches aa 77-233 of the human reference sequence [12] -VRSSSRTPSDKPVAHVVANPQAEGQLQWLNRRANALLANGVELRDNQLVVPSEGLYLIYSQVLFKGQGCPSTHVLLTH TISRIAVSYQTKVNLLSAIKSPCQRETPEGAEAKPWYEPIYLGGVFQLEKGDRLSAEINRPDYLDFAESGQVYFGIIAL - that's the same C-terminus at the end, and the same ADAM17 site as in the normal human form. I note that there's a different site at 79 used by MDC9 in vivo,[13] but I haven't looked up if that's a significant amount in the natural version (and it might not have the desired drug activity).

The other problem is that "The clinical indication for Beromun is - as an adjunct to surgery for subsequent removal of the tumour so as to delay or prevent amputation, or in the palliative situation, for irresectable soft tissue sarcoma of the limbs, used in combination with melphalan via mild hyperthermic isolated limb perfusion (ILP)." Maybe it has other indications now, or someone has an off-label use for it, but obviously, you'll have a hard time selling it to the sort of "specialised centres" that they say should be performing the procedure, and if somehow you do, well... the patients will never know about it. I wonder if people who actually care about a stray $15000 are really going to get this treatment anyway...

This approach more generally is based on Coley's toxins, a practice from the 19th century which still fires the imagination. There is such an array of potential cytokine stimulants, tumor antigens, and adjuvants that could interact to enhance an immune response - and immunology remains such a dark art - that to this day the approach offers people at least small doses of hope. Wnt (talk) 13:54, 15 October 2012 (UTC)

Well, the structure of the recombinant sounds pretty similar to the native protein, that's a homotrimer as well. The fact that's it's not cleaved from the membrane doesn't really matter, as that's not the active form anyway. The homology of the used protein is pretty good, and it will obviously be active in humans, or it would never have come anywhere near the market. The relevant datasheet[14] from the European Medicines agency, (which Wnt already linked to), actually describes the manufacturing process relatively detailed, and it's easy to see where the money goes, as it's pretty complicated. As for their indication, (without reading through the whole thing, admittedly) I can see it working in some tumours (those expressing high levels of TNFR1), but it's a very blunt approach to say the least. Certainly not going to be mild on the side-effects. On an entirely unrelated note, I was just doing some Western blotting on Wnt signalling components today, amussing to see Wnt commenting here as well.... Fgf10 (talk) 15:39, 15 October 2012 (UTC)