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September 12

Heat treating oxygen removal

Hi. To remove oxygen during Heat treating, knifemakers tear up little pieces of paper/tissue and put it in the foil pouch[1]. It's not perfect, since paper isn't pure carbon and contains contaminants, but it's cheap and easy and gets the job done.

Mass-production industrial users use vacuum furnace for heat treating, so this step isn't necessary. But prototyping industrial users also use the exact same foil pouch technique as the knifemakers.

Question 1. What do prototyping industrial users use for oxygen removal in foil pouches?

My guess is graphite, since it's cheap, porous, and (relatively) pure.

Question 2. Putting standard industrial practice and cost aside, what is the most ideal material for this task? Specifically, material X of volume V is placed in a air-tight container containing excess air and sealed. The container is heated to 500 °C for 1 hour. Which X is capable of reacting with the largest mass of oxygen in the container during this 1 hour?

My guess is either pure solid Lithium, Beryllium, or Boron. Or maybe Diamond. My reasoning is that X must be solid, since we're looking for high density. X must also have low atomic weight, so my 4 guesses are the lowest atomic weight solids with high density.Satoshit1 (talk) 18:08, 12 September 2023 (UTC)

Iron near melting point

Iron says that this element's melting point is 1538°, presumably at standard pressure. If you heat a piece of iron to 1500°, I assume it experiences some changes other than the temperature itself — blacksmiths heat iron because it's easier to work at high temperatures — but in general, will the piece of iron behave like the same piece at room temperature, or is it likely to exhibit many changes to its physical properties? I know that ice exhibits changes when it's melting, but perhaps those are the result of existing in an environment above the melting point; if the iron's being held in an ordinary room, you won't see the edges smoothing out as the surface melts, as with a piece of crushed ice. Nyttend (talk) 19:52, 12 September 2023 (UTC)

When iron is heated it first glows red, then orange, yellow, and finally white. The ideal heat for most forging is bright yellow-orange. Blacksmiths are often seen hammering on metal that is glowing red, which the article Red heat suggests may be about 814°C or 1497°F, which would be a waste of effort if the metal were not already softened at this temperature. This report describes the changes in atom packing and loss of magnetism as iron melts and eventually flows as a liquid. ~~~~ Philvoids (talk) 21:42, 12 September 2023 (UTC)

Heated iron is less brittle and more ductile, allowing it to be hammered, flattened by rollers, and worked in other ways. BTW, the extensive hammering by blacksmiths mainly serves the purpose of turning pig iron into wrought iron by working pockets of excess slag out, making it less brittle also at normal temperatures.  --Lambiam 08:40, 13 September 2023 (UTC)

See Heat treating for various lasting effects heating a piece of iron can have.  --Lambiam 09:01, 13 September 2023 (UTC)

Sorry Lambiam, but you've misunderstood the chemistry and production of wrought iron. It is a very low carbon form of iron, less than 0.05% (compare steels: around 0.1–2.1%, pig iron: 3.8–4.7%). Hammering does reduce the slag content, but doesn't change the carbon content. It's also worth pointing out that the last plant producing wrought iron commercially closed in 1973. Any genuine wrought iron today is either recycled or produced on a craft scale. Apart from this, for the last half century all "wrought iron" has been mild steel (0.05% to 0.25% C). At first glance really low carbon mild steel looks like wrought iron, but the chemical compositions are different (chiefly sulphur, phosphorous and silicon) and wrought iron is produced at a lower temperature rather than being cast, hence the slag inclusions. Martin of Sheffield (talk) 10:04, 13 September 2023 (UTC)

When I wrote "wrought iron" I meant "wrought iron", and not some "functional equivalent" produced by other methods than working the iron. I did not make a reference (also not implicitly) to the chemistry of wrought iron. Hammering is a traditional step in the process of producing wrought iron, and its purpose is as I wrote. See also this page: "Iron Making: Refining into Wrought Iron".  --Lambiam 12:13, 13 September 2023 (UTC)

Agreed wrought iron is wrought by blacksmiths and others which does reduce the slag content. However no amount of hammering can change pig iron into wrought iron. They are chemically different, therefore statement "the extensive hammering by blacksmiths mainly serves the purpose of turning pig iron into wrought iron" is incorrect. If you read the link that you gave you will see that there are two processes, "fining" (a type of bloomery) and hammering. During the fining process long bars are dipped into the metal iron and lifted up into the hot air blast. The oxygen in the air oxidises the carbon in the iron to CO (and subsequently CO2 of course). As this occurs the now purer iron collects as a spongy mass on the end of the rods and can be withdraw as "bloom". In passing, it should be noted that iron production prior to the 14thC regarded pig iron as waste, the bloomery furnace was controlled to ensure that the iron didn't melt as it was reduced from the ore.
After the fining, the pig iron has been converted into a spongy mass of wrought iron. The process of working the iron to consolidate it can now begin using a variety of hammers from the simple blacksmith's up to mechanical hammers. Martin of Sheffield (talk) 14:47, 13 September 2023 (UTC)

Oh, [snort], of course I knew it changed colour; sorry I made it sound like I didn't realise that. I meant to ask "other than temperature and colour". Nyttend (talk) 19:23, 13 September 2023 (UTC)

A first-order transition. The density of water varies discontinously at the melting point, but if you split the curve in two, both halves are smooth.

A second-order transition. The latent heat of water is a continuous function of temperature before and after the critical point, but the derivative is infinite at the critical point.

Many physical properties vary with temperature (density, mechanical strength, electrical or thermal conductivity, etc.). For most solids, many properties vary "only a little bit" when far from the phase transition. "Most solids" , "many properties" and "only a little bit" is of course extremely precise; here’s an example. The (volumetric) thermal dilation coefficients of solids are usually in the $10^{-6}-10^{-4}K^{-1}$ range. That is low compared to that of an ideal gas, which is (at room temperature) $\left(300K\right)^{-1}\approx 3\times 10^{-3}K^{-1}$.

The way I read the question, you are asking if those changes are more pronounced near a phase transition. Well, it depends on the type of phase transition. If the phase transition is discontinuous ("first-order"), then the physical properties show a "jump" near the critical temperature, but the curves just before and just after are smooth. If the phase transition is continuous ("second-order"), there are usually lots of changes in the properties near the critical point.

That might seem tautological. After all, if you have a "phase transition", it means something happens; if not a discontinuity in the value itself, then a discontinuity in the derivative of the value. However, it turns out that a great many of second-order phase transitions follow very similar scaling laws. (If you can give a good account of why that is, you are next year’s favorite for the Nobel prize.) The article about this is critical exponent (very well-written, but the topic is intrinsically complex - you need some math knowledge to read past the lead). Tigraan^{Click here for my talk page ("private" contact)} 13:26, 15 September 2023 (UTC)

I didn't know the term "phase transition". Thank you, yes, this is what I was trying to ask. Nyttend (talk) 03:31, 16 September 2023 (UTC)

September 13

physical dimension of Hertz, wavelength and Planck's law

In Wikipedia, Hertz has the physical dimension "T⁻¹", the speed "LT⁻¹", so with the wavelength which is the ratio of speed to frequency in Hz, you get the physical dimension "L" .

In Planck's law for frequency you have Si units " W·sr⁻¹·m⁻²·Hz⁻¹ ", as "W" is "J.s⁻¹" why not apply the same simplification as wavelength and get " J·sr⁻¹·m⁻² " ?

Or why the wavelength does not have Si units " m·s⁻¹·Hz⁻¹" ? Malypaet (talk) 02:47, 13 September 2023 (UTC)

The choice of units has nothing to do with Planck's law per se, but with the traditional treatment of spectral radiance. It comes in two kinds, spectral radiance in frequency and spectral radiance in wavelength. Generalizing for the kind and writing X as a placeholder for the unit of the physical quantity per which, we have for the SI units:

W·sr⁻¹·m⁻²·X⁻¹.

Replacing X by Hz gives the SI units for spectral radiance in frequency. Replacing X by m (or nm) gives the SI units for spectral radiance in wavelength. While your proposed simplification is a valid one, it hides the conceptual correspondence. In a formula said to be for something per frequency, one should expect to see Hz⁻¹, even though it is equivalent with s. Replacing W·Hz⁻¹ by J obscures the relationship with frequency even further.  --Lambiam 07:18, 13 September 2023 (UTC)

It does not obscure the relationship with frequency, it simply misses the cycle in the physical dimensions of a frequency. Because if we remove the unit of time which is shared between power and frequency, at the same time, what remains is the quantity of energy and the number of cycles that there was in this unit of time, as with kilowatt-hours for electricity billing.

Above all, what I show here with Planck's law for frequency is that there is an anomaly, where we measure a power, the equation gives energy. In both cases, the value obtained will be the same, power or energy. Doesn’t that shock anyone? Malypaet (talk) 08:10, 13 September 2023 (UTC)

Why stop at J·sr⁻¹·m⁻²? That can be simplified further to kg·sr⁻¹·s⁻², and now you have mass. Shocking! --Wrongfilter (talk) 09:34, 13 September 2023 (UTC)

Except that my simplification is recognized, I took the precaution of doing the // with the kw-h, because here my Joule is also W-s (https://en.m.wikipedia.org/wiki/ Joule#Watt-second) in the accounting sense over a time intervalle (1s), which I was told here was equivalent.

And what is the meaning of your simplification, if there is one ? Malypaet (talk) 12:19, 13 September 2023 (UTC)

Your statement shocks me because it does not make sense. I suspect the anomaly lies solely in your grasp of physics.  --Lambiam 12:27, 13 September 2023 (UTC)

You pay well for your electricity, right? You are paying for a quantity of energy over a period of time, 1 kw-h= 3,600,000 Joules. To do this, we multiply the average power over this interval by the value of this time intervalle, in this case I hope you find this normal and yet we find the same reasoning there. Average power is a flow of energy. There's not only physics in it, but also accounting and logic. The physical dimensions are there to verify consistency and you have recognized that my simplification was correct, so... Malypaet (talk) 16:29, 13 September 2023 (UTC)

Plank's law gives a relation between a whole bunch of physical quantities. The statement "where we measure a power, the equation gives energy" is devoid of meaning.  --Lambiam 07:52, 14 September 2023 (UTC)

The fact that you cannot find the meaning does not mean that there is none. I found it indirectly, during our discussions last June. Do you know about “brain storming” in problem solving and the textbook case of Swatch watches? No censorship and let your imagination run wild to solve a seemingly insoluble problem. I spent a lifetime solving problems in electronics and then in an application/data center, a Sherlock Holmes profile. Now I'm testing the reactions here, to better respond to them in my next publication, voilà. Malypaet (talk) 11:45, 14 September 2023 (UTC)

Hertz and radians are SI derived units. One has to be careful using them for dimensional analysis. For example: 1 Hz = 2π rad/s. Using physical dimensions, this leads to 1 T⁻¹ = 2π T⁻¹, which is incorrect. Giacomo Prando says "the current state of affairs leads inevitably to ghostly appearances and disappearances of the radian in the dimensional analysis of physical equations" (from Radian#Dimensional analysis) Alien878 (talk) 11:47, 13 September 2023 (UTC)

Can you provide a reference for your definition if 1 Hz = 2π rad/s? The fourth paragraph in Hertz#Definition contradicts explicitly. Angular (pseudo-)units can cause confusion, but I don't think that's the case here. --Wrongfilter (talk) 11:58, 13 September 2023 (UTC)

The magnitude of physical quantities plays no role in dimensional analysis. Although they differ by 12 orders of magnitude. the speed of light has the same dimension as the furlong per fortnight.  --Lambiam 12:22, 13 September 2023 (UTC)

Okay, that was a bad example. One cycle is not necessarily the same as one rotation. However, assuming cycles are unit-less has similar pitfalls as assuming angles are unit-less. Alien878 (talk) 12:41, 13 September 2023 (UTC)

Complete sidetrack, but what property would be best measured in furlongs per fortnight? Spread of slugs in a field, maybe? {The poster formerly known as 87.81.230.195} 51.194.81.165 (talk) 15:05, 14 September 2023 (UTC)

An earlier version of the article informed us that "a garden snail has a top speed of about 78 furlongs per fortnight". Sadly, this eminently useful but uncited fact was mercilessly deleted as being "tr[ivia]".  --Lambiam 11:38, 17 September 2023 (UTC)

Your answer begs the problem.

Speed is the number of meters per second. The meter is defined as a unit in Si by a method of measurement.

Frequency is the number of cycles per second. The cycle is not defined as a unit in the SI, yet we know how to measure it.

What good and do the slugs here? Malypaet (talk) 11:51, 15 September 2023 (UTC)

And the wavelength is the length of a cycle, right? Malypaet (talk) 12:00, 15 September 2023 (UTC)

What I meant was: units are often chosen so that the quantity being measured comes out as a small (and therefore humanly graspable) number; one commonly measures one's height in metres and/or centimetres, or feet and inches, not millimetres or chains, for example.

I was speculating that slugs might spread (in a farmer's fields, say) at the speed of a few furlongs per fortnight. It was a quip about Lambian's mention of the term, which is why I put it in small face (a thing we do here when we are trying to lighten the tone). My indentation and positioninig may have misled you: I meant to put it immediately below Lambiam's post, not Alien878's: apologies for the confusion. {The poster formerly known as 87.81.230.195} 51.194.81.165 (talk) 12:41, 15 September 2023 (UTC)

All of the replies above are quite excellent, and I would like to add to them that the unit of choice is often one of convenience for the application in question. As has been shown above, through dimensional analysis, many of these choices in units are interchangeable or interconvertible with each other, and say the same thing. Let's take that basic one of energy, which happens to be quite applicable to this conversation regarding wavelength (at least as applied to thing like electromagnetic radiation). The unit we are all often taught first in "Physics 101" is the Joule, often explained to us as a N·m. Both mean the same thing. A Joule also is expressed, in SI base, as a kg·m·s^-2, but in your classic "Physics 101" thought experiment of pushing a ball or something, that's not a very unit expression. Now, what if we are looking at mid-infrared light, such as that absorbed during molecular vibrations (FTIR spectroscopy, or the energy difference of scatter in Raman spectroscopy)? Let's take the bending vibration mode of a single molecule of water. If we express that in Joules, we get 3.28×10^-20 J, which isn't easy to comprehend, to but on an x-axis, or to distinguish between different vibrational energies. We could express it in nm, and we would get 6061 nm, which isn't so bad, until you consider the entire range these vibrations usually take place (and the fact that it can be handy to use a different set of units for vibrations than you do for visible light, just so people immediately know what you are talking about on a plot). Now we get anything from 200000 nm to 2500 nm, which is a somewhat annoying range to work with, and when you're primarily caring about higher or lower energies, having to do the mental gymnastics of "the smaller wavelength is the higher energy" is just an annoying and unnecessary step for this application. So, in the field of vibrational spectroscopy, we use the "wavenumber" unit, which is cm^-1. 1 cm^-1 = 1/(nm·(cm/10⁷nm)), which might seem annoying math at first, but if you just work in wavenumbers to begin with, that single molecule water bending vibration becomes 1650 cm^-1, and the range you are likely to work with in any molecule is 50 cm^-1 to 4000 cm^-1, which is a lot easier to work with mentally or plot on a graph. The units of choice are about the application often more than anything. In x-ray spectroscopy, nm and cm^-1 and J would all be terrible units, but keV (kilo-electron volts) works pretty well, since the range there is usually no more than 0.1 - 2000 keV (usually a smaller range, based on the type of x-ray spectroscopy being conducted, whether you are studying ejection of core electrons or just exciting them between orbital energy levels, etc.) --OuroborosCobra (talk) 14:12, 15 September 2023 (UTC)

Yes, but here the fundamental question was not about a choice of equivalent units, because between power and energy there is a subtlety. For example, kinetic energy is independent of time if there is no disturbing event. Whereas in a flow of energy, therefore a power, there is an addition of the energy elements composing the flow over time, at least in the field of accounting. In these two cases the notion of time does not have the same effect. Malypaet (talk) 18:05, 15 September 2023 (UTC)

Taxonomy/phylogeny question

If you have two species in the same family, and a third species in a sister family, am I correct in thinking that that third species is equally closely related to the first two? (I was sure this was the case, but got into an argument on Reddit with someone who claimed otherwise, and now I'm doubting myself). Iapetus (talk) 09:12, 13 September 2023 (UTC)

It depends on how you define interspecies distance. For example, one might use the edit distance between their genomes. Then it is extremely unlikely that your claim will stand. Since the split of the two confamiliar species from their MRCA, the first species may have undergone far more extensive mutations than the second, giving it a larger distance to the extrafamiliar third species. In traditional biology families are not necessarily clades and it is even conceivable that the third species is genetically closer related to one of the two confamiliar species than they are to each other.  --Lambiam 12:43, 13 September 2023 (UTC)

There is no agreed upon measurement of relation between biological species. A usually obvious difference between any two species is that they cannot interbreed. Conventional cladistics declares species related by assigning them to the same genus. Thus in binomial nomenclature, the genus name forms the first part of the binomial species name for each species within the genus. The article Genus details the varying criteria used by taxonomists. Biological family is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy under which genera (plural of genus are sorted.

Example: Panthera leo (lion) and Panthera onca (jaguar) are two species within the genus Panthera. Panthera is a genus within the family Felidae. Philvoids (talk) 13:14, 13 September 2023 (UTC)

See also species problem. --Jayron32 11:32, 14 September 2023 (UTC)

Our article at cladistics may be of assistance here. Cladistsics is an approach to phylogeny that attempts to pare down relationships to simply the last common ancestor. (I'm summarizing; our article seems pretty decent). The upshot for your question is that, you can often see which is the odd one out since the clades will show that A diverged from B/C first and then later B and C split. So, you'll know that A is less related to B and C than B and C are to each other. You'll also know that B and C are equally distant from A - neither is closer to A. Where it gets complicated is that traditional taxonomists did not have access to the tools that are available today; families and orders and so on were built up based on things like anatomical similarities. A huge amount of work has been done over the last few decades to rectify life's "family tree" with the knowledge gained by cladistics (which ultimately doesn't really care about stuff like families and orders and so on) and other tools. Matt Deres (talk) 16:38, 13 September 2023 (UTC)

So in this viewpoint the distance between two species is effectively the time elapsed since their splitting off from their MRCA. Using that as the definition, the claim that the third species is equally distant to the first two is correct.  --Lambiam 07:45, 14 September 2023 (UTC)

Thanks. That's what I thought. For the record, the argument was about the relationship between the megalodon, mako, and great white. The other guy was claiming that megalodon was more closely related to the mako than to the great white, citing a Smithsonian article that stated that but didn't show any cladograms or phylogenies. I contended that the mako and greate white were in the same family, while megalodon is now considered to be in a different family and so was equally close to both, which he rejected. Iapetus (talk) 09:39, 14 September 2023 (UTC).

Our article Megalodon has this: "It was formerly thought to be a member of the family Lamnidae and a close relative of the great white shark (Carcharodon carcharias), but has been reclassified into the extinct family Otodontidae, which diverged from the great white shark during the Early Cretaceous." This statement is unsourced. If correct, the reclassification may have taken place after February 2019, when the Smithsonian article was written.  --Lambiam 15:34, 15 September 2023 (UTC)

Burning of the Temple of Jupiter

The Temple of Jupiter Optimus Maximus article states that the second and third building both burned downed to the point that a new building would be built on the site. However, assuming that both the second and third building were most likely made mostly from stone, marble or some fire-resistant material (unlike the first building from wood), how can such non-wooden structure burn down entirely? 212.180.235.46 (talk) 15:14, 13 September 2023 (UTC)

As the recent fire at Notre Dame Cathedral demonstrates, large ostensibly stone buildings have some underpinnings made of wood. These types of mega-structures tend to push the limits of physical laws and can collapse when wooden support is weakened by fire. What you can end up with is a pile of rubble. --136.54.106.120 (talk) 18:53, 13 September 2023 (UTC)

Also read Lime kiln. This is a kind of kiln where limestone is "burned" into lime, which is a powdery substance. Even if a building doesn't rely on wooden underpinnings, it may have many inflammable contents, and if these burn inside a limestone building (which have been common for millennia), they may produce enough lime that the remnants of the blocks collapse. Nyttend (talk) 19:41, 13 September 2023 (UTC)

Just to add support to that, marble suffers from the same problem. It isn't so much that limestone and marble "burn," but rather that carbonate containing minerals, such as limestone (primarily calcium carbonate) and marble (primarily calcium carbonate and calcium magnesium carbonate) will decompose (technically, calcinate) at high temperatures, releasing the carbonate as carbon dioxide gas and leaving behind calcium oxide. When that happens, you've entirely disrupted the structure of these materials, and they crumble to powder. Quite often, stones in these areas are also high in carbonates; that's why they can mine for limestone and marble there. So, even stone itself can suffer from this problem. --OuroborosCobra (talk) 20:49, 13 September 2023 (UTC)

Thanks. Presumably there was a lot of flammable material inside the temple to sustain such a destructive fire. 212.180.235.46 (talk) 09:03, 14 September 2023 (UTC)

[Biology] What are the differences between the Cheek pouch, Gular skin, and Crop (anatomy)?

There seems to be a lot of overlap in their functions, especially regarding food. 202.190.69.201 (talk) 21:48, 13 September 2023 (UTC)

The articles indicate they are in different locations. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:52, 13 September 2023 (UTC)

Cheek pouches are normally found in some primates and rodents, and are used to store unhusked nuts, grains, etc so that the owner can grab a big load of food and carry it away to a more secure location to eat it. In a captive primate situation I have seen them used to store "stolen" keys, stones, even small scraps of a broken mirror. Crops are found in birds and are used to store grain after the bird has husked it. It can then be pushed down into the gizzard or regurgitated to feed chicks or a mate who is sitting on eggs or babies. Gular skin is not used in food storage or transport, it's purpose is more for sexual signaling or cooling. 49.177.90.146 (talk) 02:10, 15 September 2023 (UTC)

The gular skin of pelicans forms a large pouch used to store fish.  --Lambiam 13:14, 18 September 2023 (UTC)

September 14

How Do Small Changes In Composition Change The Properties Of Molecules And Atoms So Much?

Please do been helping me understand. ~~Alex Salazar 13:31, 14 September 2023 (UTC)

Can you give an example? It’s hard to know what constitutes a “small” change in composition in your mind. Also, it isn’t even always true. Sodium hydroxide and potassium hydroxide differ in 1/3rd of their atoms, and have a 40% difference in mass, but in most applications are practically interchangeable as long as the same number of moles of the salts are used. —OuroborosCobra (talk) 14:16, 14 September 2023 (UTC)

No Need for Been Attack. I will See You if I may Figure Out How This Goes. For Me I Been Suppose There Is A Duality Of Arsenic Acid And Carboxygenic Gas. ~~Alex Salazar 50.237.188.108 (talk) 14:43, 14 September 2023 (UTC)

That's a good question and one which those who design drugs and other commercially-important chemicals would love to know the full answer to! The nearest article on this subject may be Quantitative structure–activity relationship but is a bit technical for non-specialists. Roughly speaking, for drugs and pesticides the analogy of the lock and key model is usually quoted. Mike Turnbull (talk) 15:02, 14 September 2023 (UTC)

I do been wanting to tell you thank you for the citation of me, Mike Turnbull. 50.237.188.108 (talk) 15:54, 14 September 2023 (UTC)

I'm going to disagree a little bit here. That analogy works well for larger molecules (large organic compounds or full on macromolecules, like proteins), but it isn't always so easily apparent for smaller molecules or even small active sites within proteins or enzymes. The example that Alex is talking about, between what is mostly carbon dioxide and arsenic acid, that's not at all what I would consider a "small" composition change, since we have a huge elemental difference, geometry difference, etc., but what if we made it arsenic acid vs phosphoric acid? They are structurally very similar, their elemental composition is identical except for the core atom (arsenic vs phosphorous), but in terms of overall properties, this doesn't seem to have much of an impact. Their pKas are nearly identical, their melting points are fairly close, etc. However, one is extremely toxic, and the other (in moderation of course) is fairly benign and not an uncommon intentional food additive, such as in carbonated beverages. The difference is that arsenic is a metalloid, and phosphorous is strictly a non-metal. Metals and metalloids tend to love to bind to sulfur (some nice inorganic chemistry reasons that I won't get into, but look to electron configurations, d-orbitals, in other words, electron wavefunctions and quantum stuff that isn't apparent at all in a "lock and key model."). It's similarity to phosphorous allows it to bind in place of phosphoric acid in some important areas not related to sulfur, and its binding to sulfur (such as thiols in many amino acids) completely disrupts the function of vital enzymes. Put that together, and the citric acid cycle quickly breaks down, you stop making ATP, and you die. --OuroborosCobra (talk) 14:27, 15 September 2023 (UTC)

September 17

“Kilo press”

In the news today; apparently some kind of equipment used in drug manufacture kilo press. No article on it on WP, nor does it google well. Could someone write it? 2603:7000:2940:21:40F6:C37B:9009:3853 (talk) 05:38, 17 September 2023 (UTC)

It's a hydraulic press used to make the compressed bricks of drugs. Here's an FBI pic of one. I don't think there is even a Wikipedia article on illegal drug packaging in general. Abductive (reasoning) 09:10, 17 September 2023 (UTC)

For information: The fox59 link may not be usable outside the USA. In the UK I see "This content is not available in your country/region" and the tab says "Access Restricted". Martin of Sheffield (talk) 09:18, 17 September 2023 (UTC)

It is a clipping of kilogram press, a term used in releases by the judicial system^[2][3][4] and police departments^[5][6] and in news reports.^{[7][8][9][10]} Since the pressure exerted by one kilogram is puny, the name comes perhaps from the fact that these presses can compress a quantity of one kilogram into a solid brick, as advertized here.  --Lambiam 11:21, 17 September 2023 (UTC)

Wheel load 40 - 50 t/m

This page[11], under section "Crane Sizes & Technical Specifications" lists various Wheel loads from from 30 to "50 t/m".

What's "t/m"?

I think it might be metric ton per meter, but I'm not sure. I googled around and found the Axle load article which says:

The standard rail weight for British railways is now 113 lb/​yd (56.1 kg/m).

I expected a container crane to have a far higher load than a train, but not 900 times more. Satoshit1 (talk) 06:58, 17 September 2023 (UTC)

113 lb/yd is the weight of the rail, not the weight of the train. Quite literally a yard of 113 lb rail weighs 113 lb. See Rail profile#Rail weights and sizes. The axle load article mentions that British practice limits locomotives to 22.5 tonnes per axle whereas the Australian limit is 42 tonnes per axle. Martin of Sheffield (talk) 08:17, 17 September 2023 (UTC)

These port cranes run on rails using groups of wheels. All wheels in a group are connected by balance beams, to make sure all wheels are equally loaded. Within such a group, 30 to 50 tonnes per metre sounds plausible. That number determines the strength of the foundation under the tracks.

For trains, standard axle loads and metre loads have been defined. In Europe, there's a letter for the weight per axle and a number for the weight per metre; German wiki has a nice table: w:de:Streckenklasse. The standard in my country (Netherlands) is that all routes support at least 20 tonnes per axle and 6.4 tonnes per metre (class C2) up to line speed, and most also support 22.5 tonnes per axle and 8 tonnes per metre (class D4) up to 80 or 100 km/h. That's why bulk goods trains are slower than passenger or container trains and can't use some lines during the day. High axle load combined with high speed greatly increases track maintenance, a somewhat unexpected problem when faster trains were introduced in the 1960s and '70s. American and Australian trains are much heavier than European trains, but also much slower for this and other reasons. PiusImpavidus (talk) 09:56, 17 September 2023 (UTC)

How is it possible for a man to become pregnant?

I’ve seen a few people refer to pregnancy in men and I’m wondering how this happens? My understanding of physiology is that a man would not have the uterus required to gestate a fetus. There are also issues regarding gametes (males obviously lacking ova). These are probably the top two things limiting my understanding of how a man could become pregnant. Can anyone explain it to me? Codasoat (talk) 23:08, 17 September 2023 (UTC)

Where did you see this? ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:59, 17 September 2023 (UTC)

Does male pregnancy help? Matt Deres (talk) 00:43, 18 September 2023 (UTC)

Transgender pregnancy is the most relevant article.-gadfium 01:07, 18 September 2023 (UTC)

This just in: Man tests positive on pregnancy test, leaves doctor astonished. Shantavira|^{feed me} 12:07, 18 September 2023 (UTC)

That is a side effect of a metastasised tumour that had invaded his liver. Although the hormones were those usually associated with pregnancy the man was not pregnant. Martin of Sheffield (talk) 14:16, 18 September 2023 (UTC)

As suggested, transgender pregnancy is pertinent. It is referred to in press as a "pregnant man" using self-identification of gender as the definition of "man." It is not "pregnant male" using biological definition of sex at birth. It is likely that this concept if very old as any biological female in history who became pregnant could have self-identified as a man to become the first pregnant man. 12.116.29.106 (talk) 12:56, 19 September 2023 (UTC)

September 18

Dark matter attraction and Galaxy size

Let us consider 2 spheres (or disk as for Galaxy) made up of the same large number of n mass elements, therefore of the same overall mass, but of radius r and 2r, a little on the principle of galaxies in space. What is the difference in the forces of gravity applied to an object located at r/2 for the 2 spheres? I suppose that on the same principle as for galaxies and dark matter, the centripetal attraction for such an object is greater for the small sphere. Malypaet (talk) 08:58, 18 September 2023 (UTC)

If the mass is spherically symmetric, then the attraction is due to the sphere inside the radius. So what happens will depend on the mass distribution, but likely the smaller galaxy will have higher gravity at a fixed distance. In general relativity you will also have to consider gravitoelectromagnetism which will be much greater for the compact arrangement of spinning mass. Doesn't matter if matter is dark, dim or bright. Graeme Bartlett (talk) 09:57, 18 September 2023 (UTC)

"Normal" basic compounds and extreme of proton affinity

1* What is the most basic chemical compound whose molecules or ionic-molecules are overall e-neutral known? (So obviously this criteria excludes the elusive anionic species such as diethynylbenzene(2-) isomers and lithium monoxide(-)) "Known" means that the candidate chemical species must have been synthesized and detected by some means. I gave a special attention to this problem since these basic chemical species would be reasonably isolated as "normal" substances on certain inert surfaces, not just only exist as diluted gas. 2* What is the most basic inorganic/organic compound whose molecules or ionic-molecules are overall e-neutral known? (If the chemical compound in the first question turns out to be inorganic, then the second question should only be answered for the "organic" part, and vice versa). 3* Can there any inert organic solvent be used to dissolve these compounds (as in the case of liquid alkane solution of organolithium compounds)? 4* What are the values of proton affinity of these superbases, in the case they have been measured (in gas phase, of course)? A reply with a good, reliable and readable source for the mentioned compounds is appreciated. I have searched for the answers in various sites on Internet for this problem, but all cases end up with either the articles about Diethynylbenzene(2-) isomers, or the articles about unrelated aspects of more common superbase compounds */\*. 2402:800:63BC:DB8D:B5B5:F01A:57AA:1D66 (talk) 13:26, 18 September 2023 (UTC)

I'm sure you will have read the article superbase. A recent paper that it quotes is doi:10.1021/acs.jpca.2c00521 which is in a reputable journal. That article mentions some neutral superbases and comments that a reliable solvent is HMPA. Mike Turnbull (talk) 13:56, 18 September 2023 (UTC)