Wikipedia:Reference desk/Archives/Science/2016 April 12

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April 12

Methylene diphenyl diisocyanate (MDI)

I was excited yesterday to score three 55 gallon steel drums for five bucks each. I was a little bummed today to see that one, they were filled with MDI, and two, there is still a little left inside of each one. How bad is this stuff? There is probably less than 20 ounces in the bottom of each. It looks like I can treat it with water, ammonia, and detergent, but then how could I dispose of the results? The MSD sheets I've looked at show that this stuff is flammable but it does not appear to be very volatile that I can tell. After treating it I'm hoping it would be safe to use an angle grinder on it with no risk of explosion? Additional, how bad is it that a junk dealer in town has 50 or so of these drums behind his building that have not been cleaned or decontaminated and he is selling them to the public? Beach drifter (talk) 00:07, 12 April 2016 (UTC)

Well, the first thing to do is look up MSDS for it - see [1] for example. There are plenty of sour notes in there, read carefully. There is also an article Methylene diphenyl diisocyanate, though it isn't certified for staking your health on (see disclaimers!) it may help with curiosity. (The MSDS refers you to contact the company if you want to know more about safe disposal ... I dunno, that could be like calling the phone number on the barrel in Return of the Living Dead, in a good or a bad way) Wnt (talk) 00:46, 12 April 2016 (UTC)

Thanks, that MSDS was more informative than the one I had read. I'm satisfied I can clean these barrels well enough to use for some projects, but making a grill or smoker is out for these guys I think. Beach drifter (talk) 01:25, 12 April 2016 (UTC)

It's worrying that the drums were so cheap. Clean 55 gallon steel drums are selling for $20 each on eBay right now. It suggests that the cost of cleaning them out was so high that it was cheaper to (essentially) give them away than it was to clean them and sell them at the going rate. SteveBaker (talk) 13:56, 12 April 2016 (UTC)

Both the junk dealer and the foam insulation company are in a pretty rural area, so this kind of activity might occur more than I realized. Interestingly I have an invoice for the product that the (apparently one man) foam company left taped to one of the drums. Beach drifter (talk) 22:07, 12 April 2016 (UTC)

MDI is water-reactive and will even react with moisture in the air. It is highly likely that if any MDI was left in the drums that it is no longer MDI. ChemNerd (talk) 14:04, 12 April 2016 (UTC)

Well it is definitely not MDI now, as I have added water and sodium carbonate to each drum. The drums were sealed previously. The muck left in the bottom now is definitely different than the liquid I originally saw. Beach drifter (talk) 22:07, 12 April 2016 (UTC)

Sentient nerves

Do they exist in the large intestine?--178.101.224.162 (talk) 00:49, 12 April 2016 (UTC)

Sentience is not a quality that is usually held to be imbued in a given nerve. To be fair, not withstanding the great strides of modern neuroscience, we genuinely have almost no understanding of how the non-physical and nebulously-defined phenomena of consciousness arises out the physical mechanisms of the nervous system (see hard problem of consciousness), although we do have an increasingly detailed understanding of which regions of the nervous system (the brain in particular) are associated with particular mental functions, as a computational matter.

Now, there is a growing trend in neurology/cognitive science to not disassociate the brain from the rest of the body when looking at how the two give rise to a mind. But that being said, the innervation of the enteric nervous system are about as far removed from the mental processes we most associate with sentience as any part of the nervous system broadly. I think what might be causing this confusion is a phrase that has been making the rounds in recent years, that the enteric nervous system is "its own brain". This little piece of apocrypha originates from the fact that its been discovered that the enteric nervous system operates closed circuits which function all on their own, with very little in the way of feedback signals between it and the central nervous system by way of either the sympathetic or parasympathetic nervous sytems, which otherwise govern the body's autonomic functions. That is to say, the enteric nervous system knows how to keep your gut operating and generating peristalsis, even sometimes if there has been severe trauma to the pathways that link it to the rest of the nervous system. So it's a "brain" by way of it's closed functions and modularity, but the nerves within the system are not "thinking" in the traditional sense of cognitive function (though they may, in limited ways, deliver information which may influence the total human sense of self in subtle ways we don't yet appreciate, as with other quasi-somatosensory systems). Snow ^{let's rap} 02:10, 12 April 2016 (UTC)

Is this the same as Autorhythmicity in the heart? DrChrissy ^(talk) 12:37, 12 April 2016 (UTC)

Well, it's an interesting observation that made me pause to consider for at least a moment, so I want to say "yes and no", but the truth is, even drawing the broadest parallels, that the answer is mostly no. The cardiac cells which propagate the action potential are quite distinct in form and function from the cells that make up the enteric nervous system. They don't respond to stimuli, except that which is a part of their own rhythmical, rote function. They don't grow in adaptive networks characterized by weakening and strengthening of associations between given nodes as the result of the influence of need and conditioning, as even small neural circuits will. They achieve their straight-forward mechanical function through chemical channels that, relative to the functions of neurons are fairly simple and predictable (in a healthy heart, anyway). So it can't really be said that the heart has an independent "nervous system" like the ENS, but the comparison is at least on point in that the heart does conduct some of its functions involving propagation of electrical signals with minimal "oversight" from the CNS, which one could say is an accurate description of peristalsis in the intestine as well. It's an elucidating question in any event. Snow ^{let's rap} 04:37, 14 April 2016 (UTC)

Yes I think OP may have been reading pop-sci coverage like this [2]. The claims may be a bit over-sold, but Dr. Michael Gershon and the other researchers named are no quacks. On feature of ENS that stands out to me is that it has memory, e.g. this [3] journal article from 2000 says "The experiments imply that there is molecular memory of synaptic activity, just as there is memory of the effects of distending stimuli in vivo."

Another possibility for what the OP may have heard about is the influence of our gut bacteria on our brains, described e.g. here [4]. SemanticMantis (talk) 13:51, 12 April 2016 (UTC)

We know that someone who has suffered a completely severed spine in an accident is still sentient. So at the very least, it's unnecessary to have those nerves in order to be fully sentient. SteveBaker (talk) 13:53, 12 April 2016 (UTC)

• I am not sure I understand the OP's question exactly, but if you have irritable bowel syndrome, diverticulitis. or tw thirds of your colon removed, and the anastomosis fails, you will be aware enough there's something wrong that you will rather quickly be given narcotics and sedatives. If the question is, does the gut itself consciously reason? I am unaware of evidence for that. μηδείς (talk) 20:54, 12 April 2016 (UTC)

No, just wondering if you can feel a fist/arm 12" up your passage like in some videos.--178.101.224.162 (talk) 23:55, 12 April 2016 (UTC)

Oh, well why didn't you just say so? See e.g. here [5] for a scholarly study, and of course we have an article on fisting. SemanticMantis (talk) 14:46, 13 April 2016 (UTC)

I am fairly certain what's involved in that case is stimulation of the perineum and in men, also the prostate gland--google up how they do semen collection in artificial insemination in cattle. Given that people occasionally get killed by having sex with horses, I suspect there's no pain until the bowel is ruptured, in which case I can assure you there will be a lot of pain. μηδείς (talk) 16:35, 13 April 2016 (UTC)

FYI, the OP is currently suffering a blockage. ←Baseball Bugs ^{What's up, Doc?} carrots→ 13:18, 14 April 2016 (UTC)

What exactly do you mean by that state4ment BB?--178.99.232.11 (talk) 23:48, 14 April 2016 (UTC)

Compression ratio vs displacement

I'm having a hard time understanding how this can be true. We are comparing 2 vehicles with different variables. Chevy Cobalt has 2.2 liter engine displacement. Mazda 3 has 2.3 liter engine displacement. So the mazda has 0.1 liters larger displacement than the chevy. However the chevy's compression ratio is 10:1 and the mazda's is 9:1. How can an engine have larger cylinder displacement yet a smaller compression ratio? (Both cars have 4 cylinders) 199.19.248.20 (talk) 04:10, 12 April 2016 (UTC)

Why do you think the amount of compression is related to the size of the engine ? There's often the reverse-correlation, because smaller engines need a higher compression ratio and/or turbochargers/superchargers, to produce comparable power to a larger engine. StuRat (talk) 04:29, 12 April 2016 (UTC)

Both cars do NOT have superchargers, tubros, etc. Both cars have dual overhead camshaft valve train configurations. Compression ratio is the ratio of the cylinder volume with the piston at bottom dead center, when compared to the remaining volume with the piston at top dead center. Cylinder displacement is the volume the cylinder holds between bottom dead center and top dead center. With both of these definitions I'm having a hard time understanding (what appears to me) as a contradiction.199.19.248.20 (talk) 05:21, 12 April 2016 (UTC)

I didn't say that turbo/superhchargers were present on that model. I only mentioned them as an alternative way to get more power out of smaller engines, besides a high compression ratio. StuRat (talk) 05:31, 12 April 2016 (UTC)

(ec) This comes down to two factors: bore/stroke, and cylinder head shape. The Chevy may have a smaller bore and longer stroke, thus compressing the combustion gases more, or it may have a less concave cylinder head shape. That is, a smaller combustion chamber into which the gases are more tightly compressed than they are in the Mazda. Or, it may be a combination of those two factors. One engine is not necessarily better than the other on compression ratio alone; there are sound reasons and trade-offs for choosing a particular compression ratio. Akld guy (talk) 05:28, 12 April 2016 (UTC)

The Chevrolet Cobalt has a four cylinder engine. Imagine that we made that a six cylinder engine, keeping the bore, stroke, compression ratio, etc. in each cylinder the same. Larger displacement yet same compression ratio, right? Now imagine that we made that a three cylinder engine, again keeping each cylinder the same. Smaller displacement yet same compression ratio, right? --Guy Macon (talk) 05:38, 12 April 2016 (UTC)

Makes so much sense now. Thanks!! 199.19.248.20 (talk) 06:18, 12 April 2016 (UTC)

Compression ratio is the volume of the cylinder when the piston is at the very bottom of it's travel, divided by the volume when the piston is at the top. So the factors involved are the throw of the piston and the percentage of that space that is above the piston when it's at the top - which relates to the shape of the combustion chamber. None of the other numbers (bore, cubic capacity, number of cylinders, etc) matter. So it's possible (in principle) for an engine of any size and configuration to have any reasonable compression ratio - it's just a matter of design. SteveBaker (talk) 13:49, 12 April 2016 (UTC)

Flamethrowers

In World War 2-era flamethrowers, could the fuel be transferred from one flamethrower to another? So, for example, if an Allied firebat ran out of fuel, could he pick up a discarded German flamethrower and transfer the fuel from that to his own, either by siphoning or by swapping cylinders? And vice versa, could a German soldier do the same with an Allied flamethrower? 2601:646:8E01:515D:8D43:54FA:2E2E:994A (talk) 05:35, 12 April 2016 (UTC)

Even if technically possible, I doubt if the situation would have come up, because flamethrowers were used by the side with near total ground superiority in an area, to "smoke out" any enemy troops hiding in caves or rubble. So, only one side would be likely to use flamethrowers at a time. StuRat (talk) 05:43, 12 April 2016 (UTC)

I agree that one is unlikely to want to do this under live fire conditions, but I could imagine that one side might occasionally capture enemy flamethrowers when they overrun enemy bases or capture enemy soldiers. Captured military equipment was often reused. If you had captured an enemy flamethrower, then it does makes sense to ask whether or not the fuel could be used in your own model of flamethrower. Dragons flight (talk) 07:08, 12 April 2016 (UTC)

A WWII-era flamethrower used gasoline (sometimes mixed with heavy oil) as a fuel and compressed nitrogen as a propellant and small one-time-use "igniter" cylinders of something hydrogen gas to start the flame. It's just barely conceivable that you could use the fuel from one flamethrower in another (although changing the gasoline/oil mixture might screw the whole thing up) - it's not at all reasonable to assume that the propellant could be transferred - and it's as near as dammit certain that the igniters wouldn't be interchangeable.

The nitrogen tanks were pressurized to 2,000 psi - and you'd need some tight-fitting high pressure hoses with connectors compatible with one system on one end going to different connectors on the other in order to connect the two tanks, and even then, you'd only be able to transfer at most half of the nitrogen until the pressure equalized and no more would flow. Since (as previously indicated) there would be almost zero opportunities to use such a contraption - there is no way they'd bother equipping and training their soldiers to perform this tricky operation. Even if this were remotely possible, it's unlikely that the two systems would be designed to work at the same pressure - and it could easily be that you'd risk an exploding nitrogen tank if it were over-pressured - or not having enough pressure left at the end to do any good anyway.

On the fuel side, even if the (unpressurized) fuel could be transferred and would be compatible, it would probably be easier to steal a few of gallons from a jerrycan from a nearby vehicle rather than messing around with a captured enemy flamethrower. But it seems unlikely you'd run out of fuel much before you ran out of propellant gas (why provide a heavy gas cylinder that's larger than it needs to be?) - so refilling just the fuel tank would probably have been pointless because you'd run out of propellant before you could make much use of the extra fuel.

The igniters were also in limited supply. For example, the most common British weapon was provided with enough gasoline and propellant for just 10 seconds of operation - and came equipped with ten igniter cartridges for ten one-second bursts. So again, refilling the fuel and propellant tanks wouldn't help you if you were out of igniters - and getting enemy igniters that you'd somehow kludge together to work might not help if you were out of either fuel or propellant.

So this is a complete bust - not gonna happen. Too many things that would be incompatible - too little benefit in being able to do it. Unless we can find some instances of it actually happening - the answer from the available evidence has to be "No".

Much more likely would be that you'd just pick up the other weapon and use it rather than fiddling around trying to transfer stuff...but even that might be problematic. It takes some degree of skill to operate these dangerous machines - and using one left behind by the enemy might pose an unacceptable risk of the damned thing blowing up in your face if you hadn't been trained on it.

SteveBaker (talk) 13:40, 12 April 2016 (UTC)

Some time ago, I read a paper copy of the Marine report on the Battle of Kwajalein... I'm still looking for the exact title or report number (it was very probably a sub-section of Amphibious Operations bound as a separate booklet... but I recall a lot more narrative descriptions). The take-away message that I had was that you barely wanted to use your own flame weapons, let alone somebody else's. During the war in the Pacific, Japanese booby-traps were commonplace, and a rigged flamethrower would make for a very unpleasant trap. Many horrible things were done during the battle, and the use of flame weapons were probably among the worst.

While I was searching for this specific report on CARL, this came up: Portable flame thrower operations in World War II. It should be cautioned that for uninitiated readers, flame weapons are much less "cool" than Hollywood movies would make them seem. They are usually used as a negotiation tactic when verbal communication is established with a dug-in enemy soldier inside a bunker or fortified position who refuses to surrender.

The United States Army classified flame weapons as chemical warfare and no longer operates those devices in combat. Across the entire Department of Defense, use was phased out by 1978.

Commanders in the American military eventually decided to ban flame weapons.

From the tactical doctrine and training section of the report I linked above: flame soldiers (rather, infantrymen with additional training as flamethrower operators) would be trained in fueling their weapons systems, but in theater, fuel would be managed at the regiment level by a chemical warfare officer, not by an individual soldier during an assault. There are concerns about correct type and filling procedure. That report lists several additional training resource manuals, if you want to conduct deeper research.

Again, it can't be emphasized strongly enough how awful these devices are, and a little historical context might help. In today's world, our whole society stops when a hundred people are gunned down at random... in 1944, 500 American Marines burned in an accidental fuel explosion would be a minor footnote on page 134 of the report. Those were the friendly forces. Regarding enemy dead:

“

"The disposal of enemy dead ashore was a problem for the following reasons:

(a) Some had been dead for several days prior to DOG Day.

(b) Many were wholly or partly covered by debris in bloc houses, under bombproof shelter, etc., and were very difficult to remove.

(c) The stench resulting from the putrefaction of mutilated bodies made the work very obnoxious.

(d) The depth of the soil."

” — Commander Northern Attack Force - Roi Namur

Nimur (talk) 15:10, 12 April 2016 (UTC)

I wonder if the US Army or the DoD has any high level ontologists or taxonomists on staff? Maybe they could use some. Flamethrowers don't meet our WP definition of chemical weapons (hinging on toxic properties), but other definitions are viable, and surely there is some some chemical action involved in a flamethrower. However, if a flamethrower is a chemical weapon, then so is an M16, but somehow I don't think they are going to ban those any time soon. We do have an article on military taxonomy, but it's not very clear on what that's all about. But maybe there are indeed a few wonks out there pushing for better military classification schemes. SemanticMantis (talk) 15:47, 12 April 2016 (UTC)

Indeed they do employ such individuals. From our article on the Chemical Corps, here is one research report, United States Chemical Policy....

If you ever have the misfortune to receive training on, e.g. NBC weapons, the first introduction in your first lecture will likely be a historical review of chemical warfare, beginning with the semi-apocryphal Greek fire flamethrower.

I'll readily grant that "incendiary" and "chemical" are difficult definitions - and that these definitions carry a lot of emotional charge, not to mention legal and treaty ramifications. Nonetheless, in World War II, incendiary weapons such as the man-portable flame thrower were the responsibility of the Army Chemical Warfare Service.

Nimur (talk) 15:56, 12 April 2016 (UTC)

I shouldn't comment when I don't know, but I just want to disagree with the assumption that they shouldn't count as chemical weapons. They may produce fire but they also produce a lot of smoke, probably carbon monoxide etc. - if one is shot down into a bunker, will some soldiers die because of toxic gasses the flame thrower produced? There must be nuanced discussions out there somewhere. Wnt (talk) 16:40, 12 April 2016 (UTC)

Oh no, I didn't mean to say they were (or weren't) chemical weapons. My only point was that this sort of taxonomy can be deceptively difficult, and there are literally lives on the line in some cases (e.g. do I get to use this weapon to legally kill the bad guys, or would that constitute a war crime?). I do make the assertion that most any definition of "chemical weapon" that a flame thrower satisfies would also be satisfied by most any conventional gun. I realize now that Nimur did not say that flamethrowers were banned because they were considered chemical weapons, though that is still the inference I draw from my brief reading. SemanticMantis (talk) 16:46, 12 April 2016 (UTC)

OK, so getting back on topic, the answer would be: don't bother with any of this, just pick up the enemy weapon instead if you need it (or better still, get a spare flamethrower if there are any available)? 2601:646:8E01:515D:F88D:DE34:7772:8E5B (talk) 02:40, 13 April 2016 (UTC)

No, American soldiers during World War II were not trained to use captured weaponry. They were, in fact, trained not to use enemy weaponry. Unlike a video game, actual combat is conducted according to rules, designed to reduce hazard and to abide by law. One can't simply run over to the downed enemy and loot the body before it pixellates out to the respawn point.

Theft of enemy property is a war crime. (UCMJ 903 Art. 103). Enemy weaponry found during combat can be inherently hazardous, or it can be damaged, inoperative, or even rigged as a trap.

In most operations, it is incredibly unlikely that both sides would have brought a flamethrower to the same engagement. Flame weapons, in Allied armies, were specially allocated (although many commanders favored integrating the flamethrower as a regular weapon into infantry units, this never happened). Battle Experiences Against the Japanese, (May 1945). Flame weapons would only be issued to soldiers when specific combat circumstances required them: specifically, when rooting out a dug-in position.

Nimur (talk) 15:06, 13 April 2016 (UTC)

I agree - firstly, you certainly can't move fuel+propellant+igniter from an enemy flamethrower into yours - secondly, moving just fuel won't help you because when you run out of fuel you've almost certainly run out of propellant (and probably igniters) too - thirdly, you probably shouldn't (but theoretically could if life or death circumstances prevailed) pick up an enemy flame thrower and use it - fourthly, it's very unlikely (but not impossible) that both sides would simultaneously be equipped with them anyway.

So the answer is comprehensively and utterly "No!"...are we done now? SteveBaker (talk) 20:22, 13 April 2016 (UTC)

One point of law before we are done: UCMJ 903 article 103 does NOT prohibit picking up captured enemy weapons and using them in combat -- it only prohibits SELLING enemy property (paragraph (b)(2)) or keeping it for yourself after the battle and not telling your commander (paragraph (b)(1)), or stealing enemy CIVILIAN property (paragraph (b)(3)), and to claim that the simple act of taking enemy weapons during (or after) a battle somehow violates this article is just as absurd as claiming that napalm is a chemical weapon under the Geneva protocol! Nor is it true that American soldiers never used captured weapons -- in fact they DID on more than one occasion (notably, during the battle of Hill 400)! Now, SteveBaker is correct that moving fuel from an enemy flamethrower is impractical (in fact, even refueling your own flamethrower would normally require you to fall back to the weapons dump, as per the documents) and that using a captured flamethrower (unlike, say, a captured MP-40 or Mauser 98) could be dangerous unless you're specifically trained to use it (which was NOT the norm); however, his final point is not always true (notably, during the Warsaw uprising, both the Germans and the Polish partisans had flamethrowers). Now that I've said this, the documents linked earlier specifically state that a soldier who runs out of fuel (or propellant, or igniters) should bring the empty flamethrower back to the weapons dump and exchange it for a full one (which is what I meant by "get a spare one if there are any"), so this is what should be done -- and this indeed answers my question. 2601:646:8E01:515D:2D4D:1143:C62C:3988 (talk) 08:10, 14 April 2016 (UTC)

My impression from old movies is that soldiers, especially long ago, were quite resourceful about scrounging fuel and trying to get vehicles moving. It seems like pouring the fuel out of a flamethrower into a jeep or something could make sense (it seems better to try than leave it behind for the enemy) But I have no idea whether the thickeners would completely prevent it from working in an engine, even for a mile. Do you think it happened? Wnt (talk) 10:20, 14 April 2016 (UTC)

Wnt, war films may be entertaining for some viewers, but they're not reliable sources for historical information. I think somewhere in our Science Desk archive, we previously discussed the historicity and physicality of a certain war film featuring Steve McQueen's motorcycle jump in which our heroic protagonist improvised a motorcycle escape from a prison camp and proverbially literally leaps over the Wehrmacht and into Switzerland... without a helmet, no less! But if you read a history book, as it turns out, our heroic American soldiers weren't even involved. If my memory serves, Steve Baker SteveBaker ran down all the things wrong with the physics of that scene; explained how to properly fuel the serendipitously-available airplane, and more recently, again ran down the definition of "poetic license" and "suspension of disbelief." Point is - those films are fiction. They tend to embellish, at least a little bit. Nimur (talk) 14:47, 14 April 2016 (UTC)

Wow! I was on a roll that day! :-)

But my point from the Movie Stunt question was that we mostly make films about the very, very rarest of happenings. A movie about the guy who DIDN'T do those interesting or exciting things would be tedious. So even if the movie was true - it could very easily be the only time in the entire war when this ever happened. How do we know that the other 999 times that someone emptied a german flamethrower's fuel tank into a Jeep and tried to start it, they got nothing more than a GRRR-RRRR-rrrr-rrrr-rrrr-clunk? It's plausible that (for example) the Jeep where it worked had an almost full tank of gasoline already - and "dilution is the solution to pollution" - so it ran really rough, but did actually run.

SteveBaker (talk) 16:54, 14 April 2016 (UTC)

Can trisodium phosphate attack or catalyze the hydrolysis of thioethers or thiolic amino acids (cysteine and methionine, etc.) in a frying pan?

I've been playing around with trisodium phosphate while cooking (I would have gotten dibasic phosphate, but TSP was cheaper and I figured I could be free to add citric acid or vinegar to buffer the cooking process) in order to catalyze caramelization and Maillard reaction processes, and there are different optimal pH's for each chokepoint in the pathway. However, I notice with one route I took, the products *tasted* very delicious at first, intensely bittersweet (as by design) but there was this note that made me intensely nauseous and sick; it wasn't like hydrogen sulfide, but it seemed reminiscent of some sort of thiol or amine. Also, in this process I took, the TSP (in hot oil) ended up breaking down the cell walls of my ginger and garlic and released a lot of water. However, my organic chemistry classes never really informed us about high-temperature frying (oil-water emulsions). What could have happened? Yanping Nora Soong (talk) 16:10, 12 April 2016 (UTC)

To begin with, I do hope this was a food grade additive, and not borrowed from a chemistry lab! Because it's just nice to know there are no toxic impurities, and that some idiot didn't pour something back into the wrong container the week before for that matter. But assuming that, the next question would be whether it could be something extracted from the frying pan. I suppose this could be tested by a mock cook without any protein. The question after that might be what the pH really is, at least to some crude litmus approximation. But cysteine oxidation might be linked more to reactive oxygen species - see [6] - though "moderately alkaline conditions" can increase it. [7] But with several highly intense flavors mentioned, I would wonder if any of those chemicals reacted. You'd need to simplify the experimental process to its bare minimum before trying to name a culprit ... otherwise you're just guessing at culprits. Wnt (talk) 16:36, 12 April 2016 (UTC)

Right, OP would do well to come up with what is essentially a Minimal_Working_Example as part the bug fixing process. SemanticMantis (talk) 17:01, 12 April 2016 (UTC)

I used food-grade TSP from eBay ($11-15 for 2-3 pounds!). Also I have some pH paper I bought for cooking but it's on my storage unit right now (I moved). Yanping Nora Soong (talk) 17:47, 12 April 2016 (UTC)

(EC)So the idea is you were trying to use TSP to... make a steak browner? Or caramelize onions faster? Somehow add umami to your stir fry? It's a little unclear, and it might matter for the question. Anyway, have you thought about TSP's use a a degreaser? What's that mode of action on that? I wonder if you're getting some sort of TSP-driven rancidification or lipid peroxidation of the oil, independent of whatever catalytic role you're looking for. Actually the TSP article directly mentions saponification, so maybe you accidentally made soap. My suggestion is to simplify: see if you get the bad taste with TSP and oil only. SemanticMantis (talk) 16:40, 12 April 2016 (UTC)

To increase the production of advanced glycated end products (mmmm) Yanping Nora Soong (talk) 17:49, 12 April 2016 (UTC)

You don't want to activate too much RAGE though....Fgf10 (talk) 19:15, 12 April 2016 (UTC)

Yeah, but I'm not sure that consumed AGEs stay in the system for very long after first pass metabolism or even get taken up into cells. I think the problem with AGEs comes from endogeneously produced AGEs. Yanping Nora Soong (talk) 16:48, 13 April 2016 (UTC)

calculating the pH-dependent solubility product of phosphate species in the presence of calcium ions

The Ksp of calcium phosphate is 2.0 * 10^-29 and the Ksp of calcium hydrogen phosphate (Dicalcium phosphate) is 1.0 * 10^-7. It's one thing to estimate the amount of phosphate versus hydrogen phosphate from the Henderson-Hasselbalch equation, but how do I set up an expression derived from multiple Ksps, if I want to have an expression for the maximum pH-dependent concentration of any phosphate species (tribasic phosphate and dibasic phosphate?

Right now I have an expression that looks like:

• [Ca(II)] * [phosphate] / [monohydrogen phosphate] = 10^-22
• [phosphate] / [monohydrogen phosphate] = 10^(-12.4+pH)
• [Ca(II)] = 2*10^(-9.6 - pH)

But this expression doesn't give a limit to the presence of how much phosphate impurities there could be, since they were cancelled out.

This isn't related to my above question about TSP in cooking. This question is something I'm thinking about as we add 5-10 mM calcium chloride to our amino-sulfonate (HEPES etc.) buffered immunoassay reagent in an attempt to combat non-selective binding (false positives, etc.) How sensitive our reagent would be to phosphate impurities leftover from the phosphate buffer used to make our solid phase magnetic particle reagent...we already carried out a buffer exchange.) Yanping Nora Soong (talk) 18:10, 12 April 2016 (UTC)

bilateral renal agenesis likelihood an survival

What is the likelihood of survival in the instance of bilateral renal agenesis? It says that most infants don't survive beyond 4 hours, but it doesn't actually tell me the likelihood. Also I'd like to know the likelihood of an infant being born with bilateral renal agenesis, since it was stated that with unilateral renal agenesis the likelihood is 1 in 750. (Also what is the likelihood of survival for unilateral renal agenesis? Something much higher? I'd assume so, but I'd rather KNOW.) — Preceding unsigned comment added by 173.165.123.73 (talk • contribs)

“ At the completion of this study, 114 patients (73%) were alive, and the survival rate was similar to that of age-, sex-matched United States life tables. ”

From "Prognosis of patients with unilateral renal agenesis", here [8]. SemanticMantis (talk) 20:37, 12 April 2016 (UTC)

This article - http://mnmom4life.blogspot.co.uk/p/potters-syndrome-bilateral-renal.html - includes the statement that bilateral renal agenesis is 100% fatal in all cases (sic). 81.132.106.10 (talk) 16:10, 14 April 2016 (UTC)

Are there respectable studies that re-cooked starches are lower in glycemic index?

I have heard this several times since last year (that cold, and reheated pasta raises your bloodsugar less than does freshly cooked). Is there respectable research behind this? Here's an article on the subject from the BBC. μηδείς (talk) 20:36, 12 April 2016 (UTC)

Table 1, here [9] seems to support this notion. Table 3 here [10] shows how time in cold storage seems to decrease glycemic index for tortillas and beans too. Cooking method and storage of potatoes influences their glycemic index too [11]. So yeah, I think that there's respectable studies that at least generally support the notion that longer cooking times and cold storage times decrease glycemic index of many starches. I did not know that, so thanks for asking. SemanticMantis (talk) 20:43, 12 April 2016 (UTC)

You'd think they'd be shouting this from the rooftops. Damned Egg-Council Guy! μηδείς (talk) 16:27, 13 April 2016 (UTC)

Yeah @Medeis:, it is pretty interesting, and potentially valuable to many people. I was also surprised by the strength of the effect e.g. potatoes can go from rather high to rather low GI depending on cooking method, type, and storage. Fair warning: I think I misread the first link I gave on pasta. On re-reading, I think they are saying they did not find a large effect of cold storage or cook time, but acknowledge they maybe just didn't see it. Based on the other studies which do show a clear effect in beans, tortilla and potato, I suspect somewhere there is a study that shows this effect specifically for pasta storage. For potatoes though, this conclusion is very clear "Individuals who wish to minimize dietary glycemic index can be advised to precook potatoes and consume them cold or reheated." SemanticMantis (talk) 20:54, 14 April 2016 (UTC)

How do babies get good bacteria in their digestive tracts ?

Presumably their digestive tract is sterile when they are born, and mother's milk is also sterile (unless mom has an infected duct), is it not ? So, do they get healthy microbes by putting random objects in their mouths ? Do they get them from solid foods they eat later ? StuRat (talk) 20:38, 12 April 2016 (UTC)

Nope, not born sterile. See here [12] [13] for some pop science coverage. Gut_flora#Acquisition_of_gut_flora_in_human_infants indicates that many scientists used to think that infant guts were sterile, but now we know they are not. SemanticMantis (talk) 20:46, 12 April 2016 (UTC)

There is also a degree of contamination with maternal bacteria as the baby passes through the birth canal. There was some recent publicity about research showing that babies born by caesarian section had more immunological problems because they missed out on that, This was being dealt with by taking vaginal fluid from the mother and wiping it over the babies head and body to give the same effect. 81.132.106.10 (talk) 22:15, 12 April 2016 (UTC)

The baby ingests microflora off the mother's skin during breastfeeding. Roger (Dodger67) (talk) 08:01, 13 April 2016 (UTC)

Thanks, all. StuRat (talk) 15:27, 13 April 2016 (UTC)

Animals to be identified

This is another round of animals species to be identified:

• 
  Fish

the spider (first image) is very hard to identify at the image resolution provided; a sharper image would be needed. The insect (second image) is a Pentatomid bug ("shield bug"). --Dr Dima (talk) 21:57, 12 April 2016 (UTC)

Yep, could be a green stink bug, but hard to say with only a single blurry picture. SemanticMantis (talk) 14:43, 13 April 2016 (UTC)

The fish could also be any of a wide range of species - especially as there is nothing to indicate size. 81.132.106.10 (talk) 22:17, 12 April 2016 (UTC)

The fish isn't very dissimilar to a zebra fish, if the photo saturation is very washed out, which it looks like it could be. The proportions and fins look similar in any case. Vespine (talk) 22:40, 12 April 2016 (UTC)

They look like yellowtail snapper to me ([14]), though admittedly the morphology of their anterioposterior markings are a little different than anything I've seen with yellowtail before. Perhaps the OP can tell us where the pictures were taken? Snow ^{let's rap} 04:37, 13 April 2016 (UTC)

The fish are labelled 'Peixe Noronha', Portuguese for 'Noronha fish' which implies they may have been in Fernando de Noronha, off the Brazilian coast. and BTW the picture looks upside down to my eyes. Richard Avery (talk)

That would fit with yellowtail snapper, but I wouldn't rule out another species of snapper closely related but not generally classed taxonomically as yellowtail. Snow ^{let's rap} 00:22, 14 April 2016 (UTC)