Theophrastus

I'm a smidge lazy, to actually look up the precise MSDS's, but you can look up ammonium and sodium bicarbonate which are (or were) used in baking soda. Calcium sulfate, which is commonly used in plaster and chalk. Calcium carbonate as well. (Is used in chalk) Silicon dioxide, which is basically sand. Calcium chloride, I believe is used as road salt. Glutamic acid is sometimes added to salsa, if I am not mistaken. Pure metals, common in everyday life, such as magnesium, iron, and aluminum, might be worth a look. (I doubt these are all immensely toxic (obviously, as we encounter them constantly, throughout life), but I'm interested to see what it reads on the MSDS, as I do agree that while they take note of all possible percautions (for good reason, mind you) they do have a tendency to be a bit... overly cautious, at times) ps: I could list some more, but my time is sadly scarce. Au revoir!

In terms of reliability, it varies greatly based upon the textbook. I find it depends upon time frame, as eventually texts grow outdated due to further evidence, contrary to percieved fact, at the time it was published. I think that if anything you ought to examine the time frames between the published materials, and analyse it in regards to the content. If the time period is short, generally I find that a lot of the changes are more in terms revision of structure, and modification of the content in terms of what is percieved as prerequisite, what is considered necessary, and what is seen as superfluent or redundant, as well as making clarification of errors in the preceding addition. (the wonders of introductions and footnotes. This is of course also derivitive of the demands of the program, and the like. If you want to be sure, you can always try to find the newer addition at your local public library (a wonderous, not to mention free resource). In terms of experience, I haven't seen the editions you've described, and sadly in that category have little aid to give. Anyhow, best of luck!

Thanks for all the awesome input mokele! In particular, in regards to the evolutionary tendency within Opisthobranchia, of shell reduction; that is something I shall gladly add to my notes. It's also odd, because I always considered nudibranchs to have their own suborder, but it seems, from some of the research I've done following your notice, that the fact has long been reprimmanded. I suppose it serves me right for using an outdated text. As for the "sea hare," I'ld actually heard not too long ago, that one compound it produces was actually thought to be capable of treating cancer. It made it all the way to clinical tests, however, it sadly failed. I also looked further after you mentioned the nematocysts (a name that I have never heard of before), and my obvious question is- has there been any conclusive research into how nudibranchs can digest and process them, without any harm, or if that leads to nothing, what chemicals result in nematocysts' destructive capabilities. (As this by nature could hint towards a possible inhibitor, within the nudibranch) In regards to the relative time of this change, this I would still like to know as it can give further insight into why the change occured (however I certainly agree that the desire for increased mobility and versatility is a part of it). For example, mammalian evolution, really picked up the pace, following the extinction of the dinosaurs (If I remember correctly). In a similar fashion, the circumstances of the time, could dictate the relevant necessities of the animal. Thanks again for the insight, any further help in general from the rest of the community, would be most appreciated! "Sunshine, lollipops and rainbows!" (I'm not quite good with endings) Theo

Yeah, the chemistry- based dummies books are scarcely better, with various mistakes. Certainly not in the case of spelling and grammar, but key notes, structural diagrams, the nature of certain chemical reactions, things that in such a book are of the greatest importance, are commonly incorrect. Chemistry for dummies, which I skimmed through once at Chapters Indigo, I do not really have a serious problem with as due to its nature, it is evidently meant for people who want a basic understanding of chemistry, and nothing more. It lacks detail, oversimplifies, but does so simply due to the nature of its target audience. On the other hand Biochemistry for Dummies, which my parents, noting a growing interest, bought for me, is absolutely horrible. It is downright wrong on numerous accounts, and needless to say after trying to muddle through for several weeks I dropped it, and got Biochemistry and Molecular Biology by Elliot, which while not absolutely brilliant in its detail, was certainly adequate, for the purposes intended. It annoys me further because the book claims itself a supplementary text for an introductory college course to biochemistry. To the contrary however, it might be interesting to do a study, and see how many college students that dare to use it (I really pity the poor blokes) shall actually be capable of passing the class. "Guesses anyone?" -(as a percentage of the whole of course)

For various reasons, (whether for medical research, or their elusiveness) nudibranchs, have quite recently become the subject of much attention. Now I know that nudibranchs are of course related to gastropods, but have evolved in various ways, and after millions of years, they differ drastically from their gastropod relatives. One fundamental difference is the lack of a shell. Nudibranchs, instead protect themselves from predators by means of toxic secretions. What interests me is that these toxins are not produced within the body, but rather, extracted from their prey. All of these things tie into my area of question. Does anyone know at about what time evolution resulted in the rejection of the shell, and accordingly, for what reasons could this have occured, despite the shell's obvious beneficial, defensive function? Secondly, I'ld also like to know any additional information on how nudibranchs converted their digestive systems, in order to be capable of extracting key chemical toxins, from other aquatic flora and fauna, and then proceeded to store them. Any helpful responses, would be appreciated.

Anyhow, I've been stimulated by personal physical experience, to ask, as is already pre- suggested by the title, why do bulging veins occur? In that, I don't mean it in the sense of being able to see the veins clearly, due to lack of skin pigmentation, but rather that the contours of the veins quite literally bulge, so as to make themselves visible, below the skin. As well as asking the question of why this occurs, another interesting observation that I've consecutively made, which may also be open to debate, is that this seems to be a particularly prominent thing for people of Slavic origins. (Russia, Ukraine, Belarus, etc.) (Though this "statistic is one that as any, one cannot be sure of, as it is tainted by personal experience) So to conclude on a rather repetitive note: what's the deal?

Okay (he says with a redundant sigh). I know how it is that water, prisms and the like have varying indexes of refraction for the coloured constituents of light, thus breaking up "white" light, into all the visible wavelengths. (the pretty colours of the rainbow) However, my question is, why does a rainbow typically appear as an orderly arc in the sky? What is going on? Is this question one of human perception, or the science underlying the phenomena itself? I'm confused. (Theo forges a smile, in order to adequately express his thoughts) > ! (adding an exclamation point for effect )

I know that this is enevitably an obvious question, however I myself have no competence in physics, and thus curiosity has compelled me to ask: Why is it that despite a relatively uniform distribution of gravitational force, due to the sun's (somewhat) spherical shape, planets' orbits are elliptical, and not spherical? Or, in simpler terms (as I seem to have inadvertently confused myself): Why do planets have elliptical orbits? Any thoughts? (or answers:D; those are even better!)

Initially, I was a smidge unsure where precisely this question should go, seeing as it isn't quite chemistry based, but at the same time, having a knowledge of physics that would, at best be deemed mediocre, decided to put it in the general thread. I appropriately apologize to any moderator, whose unfortunate duty it may be to rectify the error. Anyhow, to get to the point, I am interested in why ferro, dia, and paramagnetism occur, in various compounds, as while I'm sure everybody knows the nature of the effects, it surprises me that I haven't thought about why such a phenomenon occurs. As always, any aid is most appreciated. "No, you have the largest cookie mr. hippopotamus!":D ps: It's best not to ask about that conclusive quote...

Philosophically inclined? Well, were you in such a predisposition, try Power, by Bertrand Russel (I've read it quite recently; quite an interesting book), or The Prince, by Niccolo Machiavelli. I haven't quite gotten to reading it yet, but from several excerpts, I've discerned to be a very realist- based approach to politics and governance. However, these books are not, like the stories of Brave New World and 1984, in that there is no plot, there are no characters, and the book serves more as a representation of particular ideas, and make for a bit of a difficult read, if you dislike the style. But... hell. Who am I to make such disclaimers? Give it a go, and (hopefully) enjoy! If you liked George Orwell, and are familiar with the revolution in Russia, (The Communistic one!) in 1917 (or 18, can't quite remember...) try reading Animal Farm. Absolutely brilliant satire and metaphors.

Greetings to all, I've been reading up on some biochemistry recently, and one example in the text in regards to the importance of BPG, decreasing the haemoglobin molecule's affinity for oxygen, was in the human foetus, which in order to extract necessary oxygen from its mother, requires for its haemoglobin to have a greater oxygen affinity, and as such, the beta subunit, is replaced by a gamma subunit. The only difference between the two, lies in the fact that the gamma subunit does not allow for the binding of BPG, and thus allows for a higher affinity for oxygen. However, as human beings mature, and as we enter this world, becoming self- sufficient in our respiratory processes, BPG becomes necessary, in order for haemoglobin to release its oxygen, in the necessary quantities to the tissues. Clearly, at some stage in development, the gamma subunits, must be converted to beta subunits. Firstly, I ask, how does this process take place? Is it a direct conversion, between the two forms through the actions of an enzyme, or is it a modification in the production agent of haemoglobin? Secondly, at what stage in development (in terms of time) does this change generally occur? As always any help in the matter, would be most appreciated!

I would like to second Hermanntrude's recommendation, though another good book into the historical progression of chemistry would be "A Short History of Chemistry," by Isaac Asimov.

Ah, a secondary question. Why does magnesium chloride, in particular, act as an anesthetic for gastropods? This, at least, must be a variation upon the initial idea, as while osmosis would be a pathway for water, for anesthetic purposes, the concentration of the solution, must be stringently controlled, and furthermore, only result in the ingestion of the necessary quantity of the salt. Why does it perform in such a manner? Surely, this must be more of a chemical action?

Ah, of course, now I understand. It's similar to the fashion cells regulate concentrations and the like. I was thinking it might have been something chemical, but it seems I've been proven wrong. Thanks iNow! :-)That question's been bugging me for quite a while. ps: sorry for the excessive use of smiles...

An interesting question on hand, for those at SFN (proclamation)! I'ts always been stereotyped in various television shows (particularly pointless children's shows, which I have sadly been coerced to watch due to the existence of younger siblings), that gastropods (regardless of genus; sometimes sea slugs, sometimes terrestrial pulmonates) seem to almost bubble and froth, in an almost disintegrative manner, when on contact with salt. Why does this seem to occur, or does it even? After all, there are tons of saltwater gastropods? I know magnesium chloride, in particular works as an anesthetic, in reasonable quantities, however, what does our dear friend common table salt have to do with it? Any help? ps: It seems that salt has a dark side as well! "(to be stated in a darth vaderly voice) Join the dark side!...we have cookies!":-)

I'ld like to say that if anyone is beginning to examine the concepts of abiogenisis, they ought to look at the famous Urey- Miller experiment, in which a mixture of gases like ammonia, hydrogen, methane and the like, that would have been prevalent in prebiotic conditions (simulating the atmospheric conditions hypothesised in the era), were subject to electrical discharge, simulating lightning, which given the violent conditions in the atmosphere at the time would not have been uncommon. After a weeks time, Urey and Miller analysed the contents of the mixture, which surprisingly, due to various chemical processes contained substancial amounts of amino acids (the majority, in the form of glycine, however, 21 others were also formed), and resulting compounds, due to further intermolecular reactions, and in varying the conditions slightly, in repeated experiments, were capable of producing a variety of organic molecules, such as nucleic acids, sugars and fats. Just something interesting for everyone to look into, in light of heated debate. I'm actually quite sorry I haven't read all of the links (to this folly I'ld attribute a lack of time), as I've read a few and they're quite interesting. Just as a note, this experiment was done in 1953! Already, over 50 years ago there was indication of the possibility of abiogenisis, so it would be interesting to see how research has progressed. I'm also a bit annoyed of these metaphors and the like, being used for DNA. DNA, I find is not digital or the like, but rather a chemical means for reproduction. It serves its purpose through chemical processes and reactions, not some magical method in which it takes the role of some manner of blueprint, or model.

Not a bad point (a rather noteworthy one in fact:-))- I suppose I myself have fallen (initially figuritively, however following this sentence, I shall make it my duty to slip off this chair for effect). (Ow!) I probably wasn't thinking straight (as if I ever am) as one would think it to be common knowledge that large magnetic fields, and external electronics equipment don't go well together. In all honesty, I never thought about that, however, the images I was referring to were only taken when the collider was only undergoing construction. Ah well, when all has been said and done, I suppose that were stupidity material, I would implode under the strength of my own gravitational field:D. Alas...

Ah, my apologies... I've given it a go, and I can't do it. It's quite strange as I believe I've done it once, which is what made me pose this question. I suppose it must have been some sort of temporary glitch. Sorry for wasting your time in that reply.

A quick question, as I wish to know this, rather than playing around with precious reputation points, but if I am to unselect the approve button beside a reputation comment, does that transform it into anti- reputation, which works against a user, or something along those lines? (yes I know, not a real word...) Or does it rather simply mean the comment is not meant to boost reputation, but is merely conversational? ps: Anti- reputation reminds me of anti- matter, just without the fuss of mass- destruction, and death.

Having read only a sparse amount of content initially, I'm actually very interested in this thread, given a previous interest in mallacology that hasn't quite receeded. I hope that if anyone finds an answer, that they post it, please. I really doubt this is a whole answer, but I know that aragonite over time, deteriorates in ordinary conditions to form calcite, and as such may be a valid reason for why there are less older aragonite- based shells. This deterioration would occur following the mollusk's death, or the mollusk's rejection of the shell, as there would be no living epithelial mantle to upkeep (is that even a word?) shell growth. I'm not sure however whether this is a solution, as I have heard that the material, retains its initial (aragonite's) needle- like (or pseudohexagonal as it is in some cases) crystal structure. Similarly, the time required for such a process, I am unsure of. My greatest hopes that we achieve our goal, of an answer, and a thanks to Cdarwin for the interesting question! Merged post follows: Consecutive posts merged(adjoin with preceding post) I've done some further research into shell structure, and found that McCrunchy's initial guess seems to be correct, as most shells, while bearing a calcite base, generally formed in crystals growing perpendicular to the mantle, the outer layer, consisting of conchiolin, an organic matrix, is generally structured parallel to the mantle, preparing the necessary conditions, to allow for aragonite, not calcite growth, on the outside surface. Together, they form the periostracum, the strong outer layer, of the shell. This of course, can be seen as optimum, as McCrunchy said, due to aragonite's greater strength, and protection is of course one of the main functions of the shell. In terms of strength, the conchiolin also allows for strong bonding with nacre, or mother- of- pearl, on the inside of the shell, and regardless, the result is one of a strong matrix for the shell. The iridescent colour of the final mother- of- pearl, is in fact due to optical interference between the layers, a testament to the structure. I'm quite sure that it has been proven that calcite, due to the oceanic conditions, 100's of millions of years ago was the primary material for the shell but it seems that it was at some point, replaced in key regions by aragonite, due to its more optimum qualities. I'm not sure about whether this is a complete trend, or whether the change is dependent upon geographic region, and other key factors, which it probably is. In terms of an evolutionary perspective, I've found that many purely calcite based shells, result from the lack of this outer layer, the periostracum, for various reasons, which as we have discussed, is based mostly of conchiolin and crystalised aragonite. However, in my research, while it seems that a calcite/ aragonite shell is more beneficial, the periostracum is not rather common amongst mollusc shells. This I think I can attribute to a similar fact to why calcite develops more readily in nature: it is simply easier. While aragonite is more conservative in the conditions it requires for formation, generally formed geologically as a product of rare conditions, as it is unstable at ordinary temperatures and pressures. Similarly, the mollusc must recreate these circumstances, for aragonite to form, whereas calcite, is a more common polymorph, as it is the one that most regularly forms, under ordinary conditions. Purely aragonite- based shells also exist, such as in the class, polyplacophora, which is particularly well- known for its hard interlinked shell plates, which protect its otherwise fragile body. As McCrunchy said, such can be seen as evolution on the mollusc's part, due to the greater strength of aragonite, however, just as before, due to the greater simplicity of the production of a calcite layer, the calcite- based shell structure remains more common. Any additional detail to what I've found is most welcome, particularly from the perspective of reasoning for this evolutionary process. Any more information, in regards to the reasoning underlying the general majority of species, utilising a calcite based shell in spite of non- optimum conditions is also welcome, as are any corrections to the above. Hope this help answer your question! ps:In regards to my initial guess, I've realised that the problem is that while the calcite morphs into aragonite, various methods of analysis of the crystal structure can easily be used to attain what the initial calcium carbonate polymorph was, which of course yields my initial idea, null and void. pps: For your bemusement and interest, I have several links to show where I'm coming from... http://en.wikipedia.org/wiki/Mollusc_shell http://en.wikipedia.org/wiki/Conchiolin http://www.ncbi.nlm.nih.gov/pubmed/17540895 ppps: While you may hear that magnesium carbonate, and calcium and magnesium phosphate minerals also exist in shells, with incredibly rare exceptions, they are only found in trace amounts, and thus irrelevant to the question, as they do not compose the base structure. Only include these if they are vital in particular biochemical reactions (thanks)

I did a similar project, (think of a science- fair type style, except without the liberty of choice for your field of study) earlier this semester, and yes, you have the essentials. I agree with captainpanic about the leaching of water into cracks in rocks, which increase in size as the water, freezing, expands. In regards to chemical equations, those, I find are quite key in making the work easily comprehensable and I recommend that you draw the crystal lattice structure of the initial and resulting minerals (examples of course) You should also mention that due to the greater surface area of crude protrusions, in contrast to flat surfaces, weathering is often spheroidal, resulting in a round- ish shape, which eases erosion and transportation of the rock. I'm not sure whether this is too late, given the time of the post, however, best of luck! Cheerio.

In terms of sex, you can also test for the presence of chromesomes, however as I said, this was within the text, so I'm guessing it is possible to attain age by means of blood samples. If you have any precise information to demean the statement, I'ld love to have it, however, I generally don't go by gut feelings. The problem I suppose is indicators. If there are no age- type indicators within blood, then it is impossible to extrapolate age. I suppose I should initially have broadened the question: Are there any chemicals, proteins hormones and the like, the quantity or quality of which can be used for the basis of an indication of age?

Wait, upon heating and the like, how would the alcohol and chlorine (or any other halogen) interact?

Good news! I've checked the library catalogue, and I found a fifth edition copy of Berg's biochemistry. It's currently on hold for me, so I should be able to get my hands on it in a week or two. Thanks for the tip; I like pretty pictures! Thanks again!

I wonder, heat would theoretically accelerate the reaction between magnesium and acetic acid. Couldn't one assume that in heating the magnesium beforehand, the reaction would accelerate? The heat would make even more acetic acid vapour, but at the same time, passing it through a sodium carbonate solution would be adequate to remove these. Unlike hydroxide, magnesium acetate is soluble, and thus, won't inhibit the furthering of the reaction like hydroxide. Anyway, I'll give it a go this afternoon, and if I finally figure out how to post pictures on the web, I'll post the results.