User talk:Johner

Hi Johner,

Thanks for your edits to Calcium Citrate and Calcium Phosphate — keep up the good work!

Here's your official welcome card:

Welcome!

Hello, Johner, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are a few good links for newcomers:

I hope you enjoy editing here and being a Wikipedian! Please sign your name on talk pages using four tildes (~~~~); this will automatically produce your name and the date. If you need help, check out Wikipedia:Questions, ask me on my talk page, or place {{helpme}} on your talk page and someone will show up shortly to answer your questions. Again, welcome! --Slashme 11:32, 23 May 2006 (UTC)[reply]

Adenosine triphosphate

Hi there, you added some data on the ionisation of ATP to this page, what source did this come from? I'm trying to improve the referencing of this article. Thanks. TimVickers 19:56, 29 December 2006 (UTC)[reply]

Essential

Johner,
Arachidonic acid is essential; see the discussion at "What is essential?" and follow the link to the Cunnane discussion.

Thanks for contributing to the EFA discussion.David.Throop 12:38, 26 January 2007 (UTC)[reply]

Essential fatty acid definition

The definition is given in the article Essential fatty acid : "they must be obtained from food as human cells have no biochemical pathways capable of producing them internally."

As far as I understand, this is not the case of arachidonic acid for the adult human since it is stated in Essential fatty acid interactions that "Most AA in the human body derives from dietary linoleic acid".

Following most assumptions, AA is an essential fatty acid for many mammals, the cat for example and perhaps also for infants but it is never considered to be an EFA for adult human. See also the Example section in Essential fatty acid where it is not cited.

Of course the fact that AA is not an EFA for adult human according to the definition does not mean that this acid is not essential for the human body metabolism.

I did not find any convincing information in the obscure Cunnane paper except that AA is probably an EFA for infants. Johner 21:22, 26 January 2007 (UTC)[reply]

The essential fatty acids were described by Burr and Burr in 1930 as those fatty acids which cured the deficiency disease brought on by a lack of fat in the diet. Arachidonic acid was one of the fatty acids which they tested and found to be effective. Further work has shown that any of the methylene-interrupted ω-3 or-6 fatty acids will work. And the common usage in the field is that the term essential fatty acid comprises all the ω-3 or-6 fatty acids (or at least the polyunsaturated methylene-interrupted ones; there are some conjugated oddities like calendic acid that aren't.) Authorative sources include the whole families, without qualification. So you have:

Heather Hutchins, MS, RD (10/19/2005). "Symposium Highlights -- Omega-3 Fatty Acids: Recommendations for Therapeutics and Prevention". {{cite web}}: Check date values in: |year= (help)CS1 maint: multiple names: authors list (link) CS1 maint: year (link)
- "Omega-3 fatty acids and their counterparts, n-6 fatty acids, are essential polyunsaturated fatty acids (PUFA) because they cannot be synthesized de novo in the body."
Nugent K, Spigelman A, Phillips R (1996). "Tissue prostaglandin levels in familial adenomatous polyposis patients treated with sulindac". Dis Colon Rectum. 39 (6): 659–62. PMID 8646953.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- "Arachidonic acid is an essential fatty acid..."
Carlstedt-Duke J, Brönnegård M, Strandvik B (1986). "Pathological regulation of arachidonic acid release in cystic fibrosis: the putative basic defect". Proc Natl Acad Sci U S A. 83 (23): 9202–6. PMID 3097647.{{cite journal}}: CS1 maint: multiple names: authors list (link)
- "[T]he turnover of essential fatty acids is increased (7). Arachidonic acid is one of the essential fatty acids affected."

You can certainly make a case that arachidonic acid (and eicosapentaenoic and DHA) aren't really essential because the body can make them, in some quantity, from lineolate or lineolinate. But that isn't how the field has generally used the term.

David.Throop 22:14, 26 January 2007 (UTC)[reply]

OK. The problem is that there are two different definitions for EFA which are used by Wiki contributors, the more restrictive one (sometimes referred to as "truly essential" or "really essential") and the one that you cite.

It is confusing for Wiki readers because only one definition (the restrictive one) is clearly given at the head of Essential fatty acid. It would be useful for the coherence of Wikipedia to give the two definitions at that place and explain that both are used in Wiki articles. Perhaps the new (enlarged) definition will subplant the restrictive one in the future but it must be recognized that the restrictive definition is still used by most authors.Johner 11:14, 27 January 2007 (UTC)[reply]

Fair enough. I'll try to work what we've discussed into a subsection under Nomenclature.David.Throop 14:11, 27 January 2007 (UTC)[reply]

That would be nice. Thank you, David, for your patience and efforts on this subject.Johner 18:13, 27 January 2007 (UTC)[reply]

Leukotriene

It would be nice to include images of leukotriene molecules in the leukotriene article as has been done for prostaglandins and prostacyclins. Johner 22:34, 27 January 2007 (UTC)[reply]

Done. David.Throop 06:19, 31 January 2007 (UTC)[reply]

Calcium carbonate

That the equilibrium results are affected by the presence of other ions is not in question. So your annotation is appropriate. But your phrasing makes it sound as if the presence of other ions removes the requirement for electrical neutrality. Of course the solution must be electrically neutral no matter what its ionic content. The presence of other ions simply means that they must be included in the neutrality equation. I haven't thought of a suitable reword for your annotation yet, but I'm posting this to you so that perhaps you will think of it and make the corresponding edit. Karl Hahn (T) (C) 21:50, 12 May 2007 (UTC)[reply]

Of course the electrical neutrality is not in question. In the case where the origin ions content of the solvent water is such that the pH is not neutral (for example a HCl solution), the anion and cation contributions do not cancel in the neutrality equation so that the equation is modified (presence of the Cl^- concentration in the above example). The result is the well known property of the strong dependence of CaCO3 solubility with the acid/alkaline character of the solvent, or stated another way of the maximum Ca++ concentration in water as a function of pH (I am confronted with this problem in my swimming pool just now). I just wanted to stress that the calculation presented in the present version of the paragraph does not take account of this important feature as it only treats the problem of the solubility of CaC03 in pure water (in which case the pH is not a free parameter).

I will try to reformulate the phrasing.

Thank you for your interest and for the considerable improvement you made to this section with respect to my first version. I must confess that I was very surprised by the interest raised by this problem. Wonderful Wikipedia ! Johner 14:19, 13 May 2007 (UTC)[reply]

I did see your update to your annotation, and I like it better than the original. Thanks. Karl Hahn (T) (C) 16:58, 14 May 2007 (UTC)[reply]

"Calcium carbonate" - preceeding => preceding

Hi,

I noticed you reverted my spelling correction for "preceding".

Looking at Wiktionary I can find a proceeding and preceding but no preceeding.

Regards,

JohnI (talk) 22:00, 3 January 2008 (UTC)[reply]

Sorry, in fact I updated the entire paragraph without checking possible changes.

"preceding" is back again.

Regards.

Johner (talk) 09:32, 4 January 2008 (UTC)[reply]

Calcium carbonate again

Hi Johner! Can you have a look at this recent diff and see if it makes any sense. I reverted it pro tem because it was a significant and unsupported change, and asked at WP:WikiProject_Chemistry/Accuracy_disputes for someone to review it but so far nobody has responded. You seem to know the topic well, so I wonder if you would help? Thanks in advance -- Timberframe (talk) 15:17, 21 September 2009 (UTC)[reply]

ArbCom elections are now open!

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