Science desk
< June 15	<< May \| June \| Jul >>	June 17 >

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.

June 16

if the half-life of estradiol cypionate is around 8 days, what would be the half life of estradiol dicypionate?

Is there a rule of thumb for estimating the half-life depot steroid medications if both hydroxyl groups on a steroid are esterified versus just one hydroxyl group? I note that estradiol dipropionate is an ester described as having a relatively long half-life, but this article seems to imply that diesterification can lengthen the half-life by two to eightfold, since before the innovation of estradiol dipropionate, most esters were injected 2-4 times a week, now could be injected once every 1-2 weeks. Yanping Nora Soong (talk) 04:12, 16 June 2018 (UTC)[reply]

According to Ullmann's "Hormones", esterification of estrogens increases their duration of action. A similar approach would be increasing the carboxylic acid chain length (like in the series Estradiol valerate, Estradiol enanthate, Estradiol cypionate). Furthermore, alkylation of estradiol derivatives at position 17 (ethinyl estradiol, quinestrol) increases their oral activity many times. --62.99.192.174 (talk) 23:39, 16 June 2018 (UTC)[reply]

This doesn't answer my question. I already know that!! I can't figure out how to apply Bates' equation in radioactive decay for a decay chain to this problem. Yanping Nora Soong (talk) 01:30, 17 June 2018 (UTC)[reply]

Do I add the half lives?? Do I multiply the half lives? I've tried all sorts of approximations and differential equations. Is the half life more like 16 days or 64 days?? The problem with the Bates equation is that it does a poor job when k1 and k2 are very close in magnitude, because you have to divide zero over zero. Agh! Yanping Nora Soong (talk) 01:33, 17 June 2018 (UTC)[reply]

I thought you were trying to deduce the pharmacokinetics of some hypothetical estradiol esters. But is it first order, zero order, nonlinear? First there is hydrolysis of the ester, then there is the metabolism of the estradiol, each of which seem to follow different kinetics, also depending on the route of administration. A Google search for "estradiol ester pharmacokinetics" and "estradiol ester metabolism kinetics" throws up lots of interesting hits. --62.99.192.174 (talk) 02:12, 17 June 2018 (UTC)[reply]

This is a a depot *diester* prodrug. Both functional groups must be removed to produce the active drug. I'm not interested in monoester pharmacokinetics and I already did the relevant research, hence why I'm here. I also tutor biochemistry... Also why aren't people reading my entire question? :( I really need help with the Bateman equation. I don't need a lecture on routes of administration for a depot formulation? Yanping Nora Soong (talk) 05:19, 17 June 2018 (UTC)[reply]

@Yanping Nora Soong: The Bateman formula gets very complicated for intermediates in a decay chain. However, the stability of the first isotope, or compound, has nothing to do with anything that comes afterward (some of those pi terms where you multiply a series of numbers don't have anything to multiply). In this case it probably is easier to redo the derivation of the math than to figure out what the formula means. You are looking at estradiol dicypionate -> estradiol cypionate -> estradiol, I think. Now do you already know the biological activity and the rate of decay for each of these intermediates? Then we can go over it. But if your assumption is that the first ester is broken at the same rate as the second, well, to begin with, we have no idea if that's true since this is biology (and chemistry...), but if it is true, then half-life of estradiol cypionate should logically be the point where just 25% of the estradiol dicypionate has been broken down to estradiol (a 50/50 chance for each bond), and two half-lives for estradiol (that would leave 25% left) would correspond to leaving 1-0.75*0.75 = 44% of the estradiol dicypionate or cypionate left. Note I'm not expecting a true half-life relationship for the "E1-2C -> estradiol decay" starting with E2C because the nature of "E1-2C" will change over time. Wnt (talk) 13:28, 17 June 2018 (UTC)[reply]

1 AU

How thick is the belt? What is the height and width? 123.108.246.27 (talk) 18:46, 16 June 2018 (UTC)[reply]

What belt? ←Baseball Bugs ^{What's up, Doc?} carrots→ 19:23, 16 June 2018 (UTC)[reply]

See Astronomical unit. Ian.thomson (talk) 19:45, 16 June 2018 (UTC)[reply]

See also Kuiper belt, possibly. If by 'width' the OP means 'span of distances from the Sun, then that article suggests 30–50 AU, hence a 'width' of about 20 AU. Thickness and height presumably mean maximum (known) distance span perpendicular to the Ecliptic plane, which the article does not specifically state, but applying simple maths (I actually drew a diagram) to the stated orbital inclinations of "up to 30°" I come up with about 35 AU either side of the ecliptic at 50 AU out, so about 70 AU. Doubtless others can find Reliable Sources for an answer better than my Synthesis/OR. {The poster formerly known as 87.81.230.195} 2.125.75.224 (talk) 09:46, 20 June 2018 (UTC)[reply]

Retaining carbonation

Suppose I want to open a cold, carbonated beverage and have it retain the maximum possible carbonation when I take the first sip, right after the pressure has dropped to atmospheric. Holding constant things like starting temperature and without previous agitation, do I lose less carbonation by the most sudden pressure drop, like popping the cap on a glass bottle, or by lowering the pressure as slowly as possible, like v-e-r-y slowly unscrewing a screw cap, and letting the pressure drop infinitesimally slowly? Or would just unscrewing a cap at a typical fast rate retain the most bubble? What is the scientific basis for the conclusion? Edison (talk) 19:06, 16 June 2018 (UTC)[reply]

If you open the cap as slowly as possible, the bottle will have been open for a long time, and will thus be entirely flat. For openings that last no more than a few seconds, I don't think it makes any appreciable difference, except that if you actually let the gas undergo free expansion it won't cool off and will thus keep the interior a bit warmer (which accelerates loss of the dissolved gas). --Tardis (talk) 21:38, 16 June 2018 (UTC)[reply]

I guess my phrasing left open the prospect of taking an hour or more to unscrew the cap, leaving the pop warm and flat. In practice, I might do it “fast” in one-half second from first escape of pressure up to 10 seconds to very slowly release the pressure from the time it is first heard hissing out. I wondered if a sudden drop, like rapid unscrewing or popping a metal cap from a glass bottle would produce a shock causing a greater loss of carbonation, similar to shaking it or setting it down hard before opening it, which clearly causes a massive loss of carbonation. As I asked initially, what topics in chemistry address the issue of the rate at which gas dissolved in liquid is liberated in a solution at atmospheric pressure. From experiments done long ago I think the volume of carbon dioxide might initially be equal to or even greater than the volume of the liquid, which itself is amazing. Edison (talk) 14:12, 17 June 2018 (UTC)[reply]

From a knowledge of brewing and beverages I can confirm your last point. The volume of CO₂ per volume (of liquid) is for real ale in good condition considered to be a little over 1. However, in other beverages it can be several times this. To quote from Beverages: Technology, Chemistry and Microbiology by Alan H. Varnam & Jane P Sutherland (Chapman & Hall 1994), p 92: "The optimum level of carbonation varies according to the flavour and perceived character of the different drinks. In general terms, fruit drinks are carbonated to a low level (ca. 1 volume CO₂), colas, ginger beer, alcohol-containing drinks, etc., to a medium level (2-3 volumes CO₂) and mixer drinks such as tonic water and ginger ale to a high level (ca. 4.5 volumes), to allow for dilutions in the non-carbonated liquor. Soda water filled into syphons, however, contains up to 6 volumes of CO₂ to maintain internal pressure during use."

My personal experience (OR warning!) of opening bottles of carbonated drinks with a higher than usual overpressure, perhaps due to warming, agitation, prolonged secondary fermentation in the container (which for real ale is by definition mandatory), or a combination of these, is that rapid opening may lead to immediate excessive foaming (aka 'fobbing') but that this can be mitigated by slower release of pressure taking at least several seconds – longer than that might reduce the over-foaming even more, but who would have the patience? {The poster formerly known as 87.81.230.195} 2.125.75.224 (talk) 13:23, 18 June 2018 (UTC)[reply]

Mystery tide pool creature (Southern California)

What is this thing? I assume it's just the mouth/siphon of something hiding in a rock crevice, and it was shooting jets of water. 169.228.163.250 (talk) 20:10, 16 June 2018 (UTC)[reply]

Dejavacrapped link: [1] Every pageview you make on the internet that Google doesn't know about is a theft, and therefore, a revolutionary act. Wnt (talk) 22:21, 16 June 2018 (UTC)[reply]

Kind of gross looking. See Trypophobia. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:41, 16 June 2018 (UTC)[reply]

I see the extremities of many thin tentacles sorrounding some thick ones sorrounding a mouth. It seems to me to be a retracted sea anemone waiting for high tide. Some see anemones do live in rock cavities, although I don't know whether they can dig one themselves. 194.174.76.21 (talk) 15:49, 18 June 2018 (UTC) Marco Pagliero Berlin[reply]