sethoflagos

7/8 I guessed +4 hours for St Petersburg.

Depends what you mean by 'overall homogeneity'. If this includes the assumption that your cross-linked product has a uniform molecular weight with exactly the same degree of cross-linking across all particles, then at least in the general case, I see no guarantee of that. Furthermore, I'd tend to view this as a multiphase mixture rather than an ideal fluid. It's more of a dispersion of solids in a liquid medium and what would the viscosity of that solid phase actually mean? But I'm straying a fair bit outside my field here. Perhaps @exchemist or @John Cuthber could add a more expert chemist's perspective.

It will heavily impact whether your software's predicted homogeneity is realistic, utter nonsense or any point between those two extremes. Really. If you're wondering what could possibly go wrong, just think 'lumpy gravy'. Bottom line is that software simulators are no substitute for laboratory work and pilot plant tests however much employers may wish that they were.

Many viscosity models for mixtures employ terms that resemble in form those that characterise entropy of mixing. So if your model indicates a homogenous viscosity, it implies that the entropy is also homogenous which is as good an indicator of complete mixing as you could wish for. You will be on fairly safe ground when dealing with say mixtures of liquid alkanes where the components are fully miscible in all proportions and where much of the research on this subject has been focussed. Don't rely on it for say a suspension of cellulose fibres.

In the absence of any explanation of how Ansys attempts to solve the advection equation in particular, then how can we be expected to judge how reliable it is?

How about Coulomb force? It is so similar in form to Newtonian gravitational force that one wonders whether it too is a fiction. Is spacetime possibly also configured to allow charge to propagate along some electromagetic geodesic as does momentum in a gravitational field? I'm sure this is an idiotic question in a sense, but I'm prepared to endure the humiliation of an informed response.

This is very good. How's this for low-loss compression? On a human level science can never compete with this. For those who think it can, the closing stanza of another poem springs to mind:

In my defence, I would suggest that there is a certain selection bias at play. I tend not to photograph those individuals I didn't notice.

In the absence of a response maybe I can add my further thoughts. If this effect gives rise to six distinct forms of hitrogen molecule (5 para, 1 ortho) and they distribute evenly at equilibrium, then surely this must contribute ln(6) R = 14.9 JK-1mol-1 to the standard entropy? However when I check references like Chem.libretexts the standard entropy for nitrogen (S0 = 191.6 JK-1mol-1) doesn't appear anomalously high. Compare with O2 (S0 = 205.1 JK-1mol-1) & CO (S0 = 197.7 JK-1mol-1). Puzzling.

This is also true of many engineering disciplines where we tend to have greater exposure to more empirical formulae. This helps reinforce the impression that the science is data-driven: that the formulae are more of a convenient shorthand for expressing correlations observed in large to very large datasets. Sometimes the correlation is so clear and simple to suggest an obvious underlying mechanism that further data may confirm. But the rooting remains firmly in real observation. I don't see how lapsing into solipsism and questioning that reality is of any help to anybody.

Would monopoles have anti-particles?

Over the last 25 years or so it has been highly amusing to see German heavy rock band Rammstein quietly but consistently appropriating and repurposing right-wing iconography to serve politically progressive purposes. It's a brilliant strategy. Absolutely immune to any accusation of 'wokeness'. But at the cost of being somewhat challenging to those who want nothing to do with that particular kind of iconography. For those of a nervous disposition, the title means exactly what you think it means so feel free not to view if you think you'll be offended. Though by doing so you'll miss some beautiful wind band intros and outros by members of the Dresdner Staatskapelle Orkester which would be a pity.

I'm not aware of there being such a marked anomaly in nitrogen specific heats as for hydrogen. Perhaps it's something to do with the relative atomic masses. Without knowing the dU and transition temperature values, it's hard to evaluate. But it should appear much like a gradual phase change over some specific temperature band. My guess is that the effect is rather small otherwise it would be cropping up in the literature quite frequently.

There are (as usual) many good points in what you say. But I'll counter with a question. Why when meteorology was quite a long established discipline, did it require a steam engineer, Guy Callendar, to ring the alarm bells? The key is I think summed up in this quote from https://www.thermopedia.com/content/796/. In other words, in order to design an efficient furnace, one needs a very clear understanding of the emissivity of CO2. A level of understanding that wouldn't be at all common in other disciplines (such as meteorology). Combustion engineering was a fairly mature technology by the 1930's and it would not have required a genius among them to extrapolate the behaviour of CO2 inside the furnace out into the wider environment. Indeed, various individuals had been doing this over the previous century or so. Callendar was simply the first to collect a reasonable dataset of historic climate records that indicated increasing anthropogenic warming correlating with an understanding that was largely concentrated within the energy and utilities sectors of industry. I guess that some meterologists at the time might have had there noses put out of joint at being upstaged by a mere engineer.

Sometimes I just can't hide my natural flair for colour coordination 😋

Actually, I enjoy cooking for myself very much and aren't too bad at it. Here's one I did earlier: I'd caught the yellowfin that morning. The sauerkraut, lime pickle and pickled onions are all homemade from local produce, other than the spices. And the darjeeling of course. The big plus of preparing your own food is that you can make whatever you want regardless of anyone else's styles and tastes. This one's a real mish-mash of different traditions so you'd be hard pressed to find anything like it on a regular menu. But you do need to dip into other styles and traditions sometimes whether to extend your repertoire, or just for the simple enjoyment of it.

Check entropy of mixing. The slightest difference in particle properties produces a significant step change in entropy irrespective of the degree of difference. It's this aspect that got me thinking about these spin isomers in the first place. Again: Gibbs' Paradox.

Hey, I'm not knocking your domestic arrangements. But we are all born into cultures that have a relatively restricted diet. Here in Nigeria I have been able to expand that diet to include such delicacies as Ethiopian nightshade, pumpkin leaf and pan-fried locust. I'm not particularly recommending these to anyone else out there, but I do think it's important to understand for instance that insects can be a viable (and surprisingly tasty) food supplement. I'm not particularly keen on the various preparations of cassava, but yam is a perfect starchy component of stews. I'm just saying that we all have a certain tunnel-vision regarding food that is culturally ingrained. We can all benefit by expanding our cultural horizons to make us less dependent on the specific diets we grew up with and along the way maybe find some unexpected delights.

Too late chum. Your comment was entirely inappropriate so welcome to my blocked list. You've nothing to say worth hearing.

That wouldn't be directed at me, would it?

I beg to differ somewhat (though I do understand where you're coming from) One thing a good restaurant does offer is the opportunity to try something new and be educated in a relatively safe environment. Yes, they can be a bit of an expense, but one expensive treat a year isn't going to break the bank. I try to make a habit of giving myself at least one treat a year, just to make what I do seem somehow worthwhile. Anyway, my treat for 2006 (I think) was to take my mother and children for week's holiday in Montparnasse. The deal was they could go wherever they wanted during the day, but the evening meal was a proper sit down job somewhere decent (ie my choice!). The highlight came at La Coupole (I think). I just remember the expression on my mother's face looking first at her 'adventurous' choice of tartare de dourade and then at my plate of la grande choucroute. Fortunately for her, I quite like raw fish and was happy to share. It was a magical bonding moment, and not lost on my then teenage son and daughter. So while I'm quite happy with regular vegetable soup and bacon omelette sandwiches on a day-to-day basis, it's good to know that there are many, many options out there.

Now I can sleep with an untroubled mind!

I'll have to sleep on that one. When I wake up may be I'll have figured out how what you said was different to what I said. Thanks nevertheless!

I found the discussion of J state populations a bit hard to follow. Is the 75% ortho equilibrium limit simply due to equipartition amongst these extra rotational degrees of freedom, or is there more to it than that?

The mental picture I'm getting is that the electron fields recoil first from the collision due in part to their much lower inertia. The consequent relative shift of -Ve potential away from the point of impact then acts on the nuclei and as @swansont says, drags them along. In the extreme case, this mechanism fails and the protons and electron seperate leading to a plasma, which we know happens so that's consistent. It's a classical picture, but there's room for a buch of vitual photons to be showering the nuclei to create some sort of Feynman diagram out of it. As regards the isomeric transition perhaps there's some really narrow window in the collision spectrum where the colliding nuclei are sufficiently closely aligned for an exchange of spin states to occur? The energy transition is in the same ball park as the latent heat of vapourisation (1.445 kJ/mol vs 0.904 kJ/mol) so the kinetics seem credible even if the actual mechanism is opaque. In passing, I find it intriguing that such a quantum oriented phenomenon can have such a marked impact on bulk thermodynamic properties. The anomalous behaviour of the specific heat of hydrogen at low temperatures has been known for a long time of course. It's a classic case of Gibb's paradox: the tiniest imaginable difference between particle species is sufficient to cause a significant step change in macroscopic entropy.