Wikipedia:Reference desk/Archives/Science/2018 June 7

= June 7 =

Except for adrenal gland and kidney are there another organs with cortex and medulla?
Except for adrenal gland and kidney are there another (parenchimal) organs with cortex and medulla? --93.126.116.89 (talk) 01:26, 7 June 2018 (UTC)
 * The brain. See cerebral cortex and medulla oblongata.-- Jayron 32 01:52, 7 June 2018 (UTC)
 * That's different, in the brain it's not like everything that's inside the cortex is medulla, like in the kidney, in fact the medulla isn't inside the cortex at all. Fgf10 (talk) 08:14, 7 June 2018 (UTC)


 * Some of these might be excluded by your question, but ovaries, the thymus, lymph nodes, bones and hair. Adrian J. Hunter(talk•contribs) 02:25, 7 June 2018 (UTC)


 * It's actually not a very meaningful question, unless you are asking about the words, in which case the answers above are correct. "Cortex", derived from the Latin for "bark", simply means a layer of tissue covering the surface of an organ, and "medulla" means a mass of tissue in the interior of an organ. Many organs/organ systems have that sort of structure, and, as Adrian said, those specific words are used for a number of them. Looie496 (talk) 12:18, 7 June 2018 (UTC)

Guns etc. and hi-explosive
I think material-science has progressed so much nowadays, remember space-vehicles, fighter-aircraft, submarines (temperature and pressure they must tolerate!) My question is that why don't they still use RDX or any other hi-explosive in military rifles's cartridges, don't they already use it in heavy-artillery shells ? Jon Ascton   (talk)  12:06, 7 June 2018 (UTC)
 * Bombing_up_106_Squadron_Lancaster_WWII_IWM_CH_12541.jpg]]


 * An explosive weapon generally uses high explosive to project blast and/or fragmentation from a point of detonation. The article Explosive material gives details of types and properties of a long list of materials.


 * World War II saw an extensive use of new explosives (see List of explosives used during World War II). In turn, these have largely been replaced by more powerful explosives such as C-4 and PETN. However, C-4 and PETN react with metal and catch fire easily, yet unlike TNT, C-4 and PETN are waterproof and malleable.


 * The term RDX metioned by the OP is a relic of British security naming "Research Department Explosive" of an organic compound (O2NNCH2)3 also known as cyclonite, hexogen, T4, and, chemically, as cyclotrimethylenetrinitramine. It has been widely manufactured and used as a military explosive component since WW2 (see illustration) as reported at RDX. Lately FOX-7 is offered as a low-sensitivity replacement for RDX. DroneB (talk) 14:56, 7 June 2018 (UTC)


 * For further reading: "greener charges", (2015): "Engineers at Picatinny Arsenal are developing a new propelling charge for the family of 105mm artillery cartridges that are safer for the warfighter by eliminating the use of lead and other toxic substances present in the current charge." Replacing the lead bag liners with bismuth was a minor but important change, and it's not even modifying the energetic compound chemistry!
 * I think it's fair to summarize that in this century, engineers aren't making significant changes to high explosive chemistry: the body of knowledge developed since 1900 is fairly thorough, and we know how to make explosive chemicals that are safe, nonvolatile, effective, compact, lightweight; that remain functional when exposed to heat, cold, humidity; water, salt, jungle mud, desert sand, chemical weapons, biological contaminants, nuclear radiation, and the nasty cleaning processes to wash off all that other stuff...; that can be transported by sea, air, land; that can be handled without going off unexpectedly; ... I mean, those very important scientific and technical advances were already mature by the 1940s, and by now we're pretty much just in "maintenance mode."
 * The big explosive chemistry news, which is almost ten years old, was IMX-101, the new explosive mix designed to replace TNT. Here's a Sandia report, "Interactions Between Ingredients in IMX-101".
 * If you're really interested in what's new in explosive technology, here are a few more websites to peruse:
 * Sandia Research Magazine
 * Poulter Lab, at SRI
 * Armed with Science, the official United States Department of Defense Science Blog
 * Why is all this scary, accurate, and specific information about high explosive chemistry available for zero cost on the internet? Because generally, scientists who study such things know that having easy access to dangerous information via the internet is not actually very likely to stimulate violent extremism.
 * On the other hand, if we have an informed public, we might make scientifically-sound, well-guided decisions, like funding research-efforts to reduce the hazardous materials used in our incredibly-massive defense industry; and we might be more inclined vote for people who use fact, knowledge, and critical thinking to guide policy-decisions, especially pertaining to unpleasant subjects.
 * Nimur (talk) 15:59, 7 June 2018 (UTC)
 * As an answer to OP's question, I recall hearing that high explosives are not suited to propel bullets down the barrel of a handgun or rifle because they are too explosive. Gunpowder burns slow enough to accelerate the bullet down the entire length of the barrel, whereas a more explosive chemical is a worse propellant. Anyway, I didn't bother looking this up, but I'm pretty sure. Abductive  (reasoning) 17:41, 7 June 2018 (UTC)
 * Yes. See the difference between propellant, explosive, high explosive, deflagration, detonation et al (some disambig needed).
 * Explosives are of little use as propellants for guns, either small arms or artillery. They make them explode. Some, such as blackpowder, are on the borders between.  In large, solid grains (with a limited surface area to volume) they may be restricted to burning slowly enough that they can be used as propellants. If that goes wrong (such as mechanically damaged grains), the effects can be explosive and dangerous (at the wrong end).
 * Explosives too have a similar distinction (and a big one on cost too). ANFO, ammonium nitrate and TNT have low Vdet and are used for mining (either meaning) and demolition of masonry (and they're cheaper). Those used for quarrying (where the stone needs to be released in good condition) might use watergels, which are even lower, or traditional coarse gunpowder. In contrast, RDX / C4 et al. have high brisance, a high Vdet and produce shock waves. They can thus be used to make shaped charges too. This makes them useful for the controlled demolition of steelwork (with very small charges) where the steel is cut in a narrow plane, either by jet of hot material, or by shock wave. The rest of the steel needn't be disturbed (and you don't need to pay for the explosive that would have been needed to move the rest). Militarily that also makes them suitable for other devices, such as HESH (more shock waves). Andy Dingley (talk) 18:04, 7 June 2018 (UTC)
 * Either Abductive or I is misunderstanding you — Abductive took you to mean the use of explosives as propellant, while I take you to mean the use of explosive bullets. This happens in the cartoons (pretty sure I've seen Wiley Coyote use them, for example), but for most purposes it doesn't work or is unnecessary; bullets generally work because they're dense and fast (there's tons of momentum being applied at a specific location), so they can do lots of damage before they leave the body or lodge somewhere in the body.  And if you have reason to have the bullet explode, this can be done with the structure of the bullet itself (no explosives needed); see Expanding bullet.  Finally, remember that bullets' high momentum and piercing power would be lost in some cases if they exploded; expanding bullets can't pierce walls, for example, and a bullet filled with explosives wouldn't be able to go as far into something as a non-exploding bullet would.  Nyttend (talk) 00:15, 8 June 2018 (UTC)

antigen Vs. pathogen
I googled it and found different opinions about the difference between antigen and pathogen. Some say that pathogen is a microrganism and some say that it can be any substance that trigger the immune system. But others say the same about antigen. So the difference between them isn't clear to me. Then my question here is what's widely accepted? --93.126.116.89 (talk) 23:30, 7 June 2018 (UTC)
 * A Pathogen is anything that causes a disease, whether it's a microorganism or a substance, whether or not the disease triggers an immune response.
 * An Antigen is a molecule that triggers an immune response, whether or not this is caused by a disease or something else (like pollen). Ian.thomson (talk) 23:42, 7 June 2018 (UTC)
 * "gen" means "to create" or "to give birth to". A "patho"gen is a substance that creates a disease (patho- meaning disease or sickness, c.f. pathology) and an "anti"gen creates an oppositional response (anti- meaning opposed to).  -- Jayron 32 01:04, 8 June 2018 (UTC)
 * (ec)The way I read antigen and pathogen, an antigen is a molecule, whereas a pathogen is a microbe such as a bacterium or a virus. If the articles were written based on the best sources, then they should reflect what is generally accepted. ←Baseball Bugs What's up, Doc? carrots→ 23:44, 7 June 2018 (UTC)
 * There are pathogenic molecules as well, i.e. prions. -- Jayron 32 01:04, 8 June 2018 (UTC)
 * The "broad 1880s" sense at the beginning of pathogen is essentially never used in current discussion. For example, polonium-210 or dioxin or Novichok agents are not called "pathogens".  Note also that that broad sense is not the same as the "any substance that can trigger the immune system" mentioned above, which is much closer to the meaning of antigen.  (If there is any difference from 'antigen', it would be related to how haptens are interpreted in that phrase)  There are a few substances which are toxic and trigger the immune system which are therefore classifiable both as "antigen" and as "pathogen" in that archaic sense but which are not replicating disease-causing agents, notably the drug that idiots at TeGenero dosed according to its chimp-human cross-reactivity in their trial, therefore cratering its chances and their company and the poor saps injected with it as well. Wnt (talk) 10:55, 8 June 2018 (UTC)