exchemist
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Everything posted by exchemist
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According to current models, perhaps.
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Surely that is not what science teaches, though? Science gives us predictive models of the physical world, none of which can be proven and consequently none of which can be said to be definitively right.
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But surely these all lighten the skin , by breaking down melanins or inhibiting their synthesis. Thatās the opposite of what the OP is asking about.
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Breast sagging natural vs with a bra
exchemist replied to annie24's topic in Biochemistry and Molecular Biology
Thatās what I did. She got on the scales and I put my hand under one breast, lifted it to the point at which the tension appeared to be gone from the upper slope, and noted the decrease in scale reading. Then ditto with the other. Not very accurate perhaps but gave us an idea. She had quite a generous, though not excessive, bust. Most of my other girlfriends had smaller breasts and a less earthy sense of humour, so the subject never came up with them. š -
Indeed very hard to control for all the variables involved here. Purely anecdotally, my observation is that fatter people often eat more, and often they eat worse, i.e. more ready meals and junk food. Having said that, it is definitely not always the case, so there are other issues to do with varying propensity to convert calories to fat. Some of these effects appear to be hereditary.
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Breast sagging natural vs with a bra
exchemist replied to annie24's topic in Biochemistry and Molecular Biology
I have only had the opportunity to research a small sample ( 12) in the course of a longish life, but in spite of the considerable variety of shapes and sizes I have never observed any musculature in breasts, even though I belonged to a rowing club for over 30 years and married a rower. (I did once try to weigh them though. This arose from a discussion of the old-fashioned appreciative remark āBlimey, you donāt get many of them to the pound!ā - a reference to how one used to buy fruit at the greengrocer. She was a nurse, so was happy, in fact highly amused, to enter into the spirit of the exercise. In her case about a lb each so it was true, for her.) -
Breast sagging natural vs with a bra
exchemist replied to annie24's topic in Biochemistry and Molecular Biology
What? No. What we are saying is a bra that supports the breast will change the shape of the breast but not its volume. Thatās all. Iāve come across what you say here about muscles supporting the breast before. Iāve always struggled a bit with it. What muscles are those? My impression has been that breasts are fairly inert, changing shape as they do when a woman lies down, or stands up, or bends over. So Iām a bit suspicious about muscle tone affecting their shape. But itās not something I have ever got round to discussing with a woman - and I have never gone out with a physiotherapist who might have been an authority on the topic. A quick search threw up this reference, which is in line with my scepticism about any role for muscles in affecting breast shape: https://www.livestrong.com/article/525163-the-results-of-exercise-on-the-female-breast/ -
See also the 2nd thread started by this person. I'm now suspicious this a bot essay-writing exercise with no science behind it. What is particularly suspicious is that this new 2nd thread purports to address the issue I raised here of the need to consider what solvent alternative life chemistries would use, and was posted about an hour after I raised the issue.
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The passage highlighted in red is bullshit. The liquid range of ammonia at STP is from -78C to -33C, a range of only 45 Celsius, compared to a 100 Celsius range for liquid water. My suspicions about this screed of text are now aroused. Like your other thread, It seems be a load of pompous, flowery language, with little or no understanding of science behind it. Are you a real person or just a stupid AI robot, sent here to waste our time? I shall take failure to respond substantively to this as evidence you are the latter.
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Not sure. In practice it looks as if synthesis of HFCs was not not done by "burning" hydrocarbons in fluorine gas, which probably just gives you an unholy mess, but by a more more controlled reaction, involving ionic displacement of Cl by F, or addition of HF across C=C double bonds, and processes like that.
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Yes, somewhat: C-H ~ 400kJ/mol vs. C-F ~ 480kJ/mol. For comparison C-C and C-O are ~ 350kJ/mol. Diatomic fluorine gas is certainly highly reactive and tends to displace hydrogen from organic compounds (in fact often "burning", complete with flame, as if it were oxygen!) , but this is largely due to the anomalously low bond energy of the F-F bond, which is thus easy to break. This low bond energy is attributed to the small size of the atom: high nuclear charge for a given valence shell (n= 2) as one gets towards the right of the 1st short period, so forming the bond to complete the valence shell introduces a lot of electron-electron repulsion - more so than for larger atoms. So I think it's more the instability of fluorine gas than the stability of the compounds it forms. A range of perfectly stable compounds with mixed C-H and C-F bonds is available (HFCs were one of the greenhouse gas bad actors in former refrigerants), so the disparity in bond energy does not prevent F playing a fairly well-behaved role in organic chemistry.
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Yes, like @joigus and @swansont I don't follow this. Fluorocarbons don't require any less carbon than hydrocarbons, for a given chain length. The virtue of carbon, surely, is its unique propensity for catenation, viz. forming long chains, linked by covalent bonds. Your proposal does nothing to lessen dependence on this so far as I can see. Fluorine forms only a single bond, so can't substitute for carbon in this role. By looking at fluorocarbons all you are doing is substituting F for H. As H is the most abundant element in the universe, that would seem, on the face of it, an exercise of doubtful value. Graph of relative elemental abundances below: From: https://en.wikipedia.org/wiki/Abundance_of_the_chemical_elements You also need to pay some attention to what solvent a life chemistry will use. Water would be fairly useless with fluorocarbons, I suspect. Are you envisaging HF or something as the solvent?
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Breast sagging natural vs with a bra
exchemist replied to annie24's topic in Biochemistry and Molecular Biology
Or perhaps the poster meant not volume but bust measurement. That would presumably be a bit less without support. -
Breast sagging natural vs with a bra
exchemist replied to annie24's topic in Biochemistry and Molecular Biology
Why would whether they are in a bra or not affect volume? I would expect the volume to be the same, but just the shape to be different. -
Determinism shown to end contradiction
exchemist replied to jnana's topic in Modern and Theoretical Physics
So far as I can discover, this Dean bloke seems to be some sort of self-promoting (and quite likely self-publishing) nutcase. I canāt find evidence that anyone takes him seriously. What you have posted about his arguments does little to alter my impression. Are you Dean? -
do you believe demon possessions and fallen angels are real
exchemist replied to knowledgeispower917's topic in Religion
Suggest you first consult a dictionary and then come back with any specific points of clarification that you may have. -
Did contaminated fuel cause the Baltimore bridge disaster ?
exchemist replied to toucana's topic in Engineering
Main engine will be RFO for sure. Itās a big one: 9 cylinders of 90cm bore. (The C will I think stand for container ship, normally meaning higher rpm and shorter stroke than, say, the variant for tankers.) However I have just remembered it used to be the practice in some areas to switch to MDF in coastal movements, to comply with local emissions regulations. So what you posted about MDF could be relevant. -
Did contaminated fuel cause the Baltimore bridge disaster ?
exchemist replied to toucana's topic in Engineering
Your link is about MDF. I wonder if the ship was burning that or RFO. (My comments about centrifugal separators relate to RFO.) I heard an interview with a bridge designers saying that if and when they rebuild it, it will probably be a cable stay bridge with piers set much wider apart, well out of the navigable channel.