exchemist

Zero is also part of the set of real numbers, isn't it?

I don't know the answer: I was hoping you might, having had it drawn to your attention! But, looking at the ring structure of lactose, on the glucose ring one of the -OH groups is part of the hemi-acetal. If you exclude that one, there remain 3 of them on the glucopyranose ring and 4 on the galactopyranose ring. HOWEVER, looking in my ancient Finar Part 2 (old-fashioned, even at Oxford in the 1970s!) it looks to me as if the methylated OH that is part of the hemi-acetal is hydrolysed in the following hydrolysis step, leaving you with only 3 methylated hydroxyls on the glucose side. So that would account for it. (That would make sense as acetals are easily hydrolysed to give the aldehyde or ketone.) I think that's about the best I can do on this. I hope you can construct an answer now that makes some sort of sense. If we've got it wrong, I'd be interested if you can come back here and let me know the right answer in due course. I must say I found carbohydrate chemistry terribly confusing and tedious, due to the close similarity of all these structures. And the lecturer we had was the most boring man imaginable. So I'm afraid the details are not something that has stayed in my mind 45 years later......... 😁

Well I that's how it looks to me, yes - unless someone else can point out an elephant trap of some kind that we have both missed. But maybe in your answer you need to go through what happens with each procedure, i.e. how Fehling's solution reacts with the free aldehyde, how the -OH groups get methylated, and so forth, in order to show that you have understood the chemistry the question talks about. Do you think that is reasonable? P.S. Why do you think the glucopyranose is only trimethylated?

OK, so what can you say now about this disaccharide?

OK this is not my area of chemistry (I hated carbohydrate chemistry at university), but maybe we can crack this problem between us. First, what does Fehling's solution test for, i.e. what can you say about the disaccharide from the fact it reduces it? Second, what does permethylation do to a sugar? Third, what would a disaccharide involving galactopyranose and glucopyranose suggest to you?

Yes, that's why I selected these links. They also relate to Omicron (the first link has several documents, only one of which is relevant, I think).

How do you propose to generalise from an electronic example to chemistry? And what is the principle, or insight, you want to take from electronics and apply to other cases?

Surely the processes that damp out waves involve energy conversion to heat, through fluid friction, and friction of the fluid against the walls of the containing vessel. If there were no such friction, and gravity were the only influence acting, the waves would continue to reverberate without diminution, wouldn't they? Just as a pendulum would continue to swing indefinitely if it were not for friction.

If there is partial melting then the temperature will not be below zero C. The rest of the freezer will be kept close to zero, but may be slightly above, due to whatever heat leakage there may be through the insulation, which won't be perfect. But I don't think there is any magic about zero C, from the point of view of keeping food from spoiling. Food will keep almost as long at 1C as at 0C. But it's interesting. It's all about suppressing the growth of bacteria. I'm not sure if this is just like a chemical reaction viz. an exponential function of absolute temperature, or whether here is any sharp "switch on" temperature below which they cease to multiply entirely. I can imagine that if the bacterial cytoplasm freezes, all activity may stop. Perhaps someone else can comment.

Well, Arfa, I freely admit I find you confusing, but then you do seem to be flip-flopping between an experiment in an electronic circuit and experiments in general. For instance, how am I to reconcile the two passages I have highlighted in red in your previous post?

I'm sure that after a moment's thought you will be able to think of plenty of experiments that don't involve electricity. Trying to apply Kirchoff's laws to an organic chemical synthesis, or to an experiment on the behaviour of insects, would strike me as pretty crazy, at any rate.

The same as it applies to any other transverse gravity wave on a water surface. The side of the glass moves inward and outward, alternately displacing the edge of the water surface up and down, and then gravity makes the raised surface fall back, or the depressed surface rise back (due to the water displaced upward elsewhere), creating a wave. This behaviour is described in the link I provided. No elastic property of the medium itself is involved, any more than it is in waves on the sea.

It has already been pointed out on this thread, though possibly not explicitly enough. A wave involves displacement of part of a medium from its equilibrium state, creating a restoring influence (a force, in the case of material media) that tends to return the displaced portion to equilibrium. In the case of a surface wave on a liquid (at least on the earth, as in the wine glass), that force is due to gravity. They are transverse gravity waves: https://en.wikipedia.org/wiki/Gravity_wave. The restoring force is thus not due to any elastic property of the liquid. Sound waves in an organ pipe are due to compression and rarefaction of air, which creates restoring forces due to the pressure differences created. These are longitudinal compression waves: https://en.wikipedia.org/wiki/Longitudinal_wave in which it is the elastic behaviour of the medium that causes the restoring force.

You can do plenty of experiments that don't involve anything electrical at all. So it doesn't seem to me that trying to relate the information obtained from an experiment to voltages is a particularly helpful line of enquiry. Arfa?

Why are you muddling up sound (i.e. pressure) waves in an easily compressible medium, like air, with surface waves on the surface of a liquid? The restoring forces in these two cases are due to quite different things.

If your floor is reasonably clean, then I think the bigger issue will be the fact that the food has been exposed to the microbes in the air, because of the hole, for perhaps quite a long period. You don't say what this meal consists of (whether dry or wet, cooked or uncooked, etc). If it was a hot, cooked meal such as a stew, that was supposed to have been sealed from the air in a sterile state after cooking, then you might want to be a bit careful if it has been kept in something with a hole in it for several days. But I really doubt that a few seconds contact with a clean kitchen floor will do much harm.

I'm not what sources you are relying on but in the UK here seems to be a fair amount of evidence that the vaccines work pretty well at reducing the severity of infection with the Omicron variant. There is a paper here on it: https://www.gov.uk/guidance/monitoring-reports-of-the-effectiveness-of-covid-19-vaccination And here: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1046479/S1479_Imperial_Severity.pdf

No it doesn't. Human beings can be seen to be close relatives of the other apes. The relationship to other animals is plainly more distant.

A few observations: We do not know what happened before the Big Bang. It is conjecture. Extrapolation points to a singularity, which would in some models have represented the start of time, in which case there could not have been anything "before". But we don't know if such extrapolation is valid. So what you have written is not "pure science". Absolute zero relates to temperature, the temperature at which no more heat can be extracted from matter. That has nothing to do with the dimensions of the cosmos. So far as I am ware, the term "virtual number" relates to telephone numbers. Zero is a point on the the real number line. But this is the case irrespective of any cosmological model.

Yes under those conditions surface tension provided a (very small) force that seeks to minimise the surface. OK, I should have said "behaves elastically" rather than "is elastic". Is that better?

Sure, but that is not responsible for the restoring force in surface waves on a liquid, which is the the scenario under discussion. That restoring force is gravity, which is not intrinsic to the material.

There was a young man named Green, Who invented a w*nking machine. On the ninety-ninth stroke, The bloody thing broke, And whipped his balls into cream.

A liquid, however, has no shape. It takes on the shape of its container. @Ken Fabian's comments seem to be spot-on. An elastic substance resists deformation, by means of a restoring force generated by the material itself. It is rather perverse to maintain a liquid is elastic, when the only force restoring the surface to flatness is external to the material, viz. gravity.

I agree, but another crucial point about laws is that they represents a common, agreed standard by which conduct can be judged by the community. Laws remove the arbitrary element in deciding whether conduct is acceptable and thereby enable consistency and fairness - which in the end stops us all fighting one another in private disputes.

Professor Bargh sounds like a Private Eye joke. But I mustn't be bitchy...... Seriously I'm not sure how any of this can be applied. Personally, when I find myself in conversation with some who recites a lot of words like respect, respectful and patient, I find I soon want to get away, before my toes start curling.