paulsutton

Sorry for the delay in this. The book I have is : Structural Mechanics Second Edition Ray Hulse & Jack Cain ISBN: 978-0-335-80457-5 palgrave.com

Yes, Nature does have a canny ability to throw a spanner in the works of current thinking, Even the JWST is re writing our understanding of the universe early history, so as you said nature has many things that don't fit. Once we reach the moon, we will probably end up re-writing everything on stress based on what we learn in micro gravity on the moon. Different environment will throw up more problems, just that the stakes will be much higher i guess, as we can't evacuate a moon base. As we are talking about materials and stresses, what do people make of this?77 'It's crazy' - villagers mystified as river dramatically changes course https://www.bbc.co.uk/news/articles/cqxlv7x1527o Would there be a connection, it does look like human intervention by land owners may have had unexpected consequences.

I found a book in a charity shop on Structural Mechanics which seems to cover some (or may be all) the topics @studiot is covering so I I will give that a read too.

I was thinking that, given that 1 mole of a substance still has the same number of atoms, e,g 1 gram of Hydrogen and 238 grams of Uranium would still have 6.022 x 10^23 atoms. So they may calculate based on that, and as you said infer the 1/2 life. Maybe that is a question for another thread.

That is pretty cool, I wonder what he would think about the fact that his experiment is still going after nearly 100 years, Then again look at the 1/2 life of some radioactive isotopes, some take seconds others take days, months or even years.

Is this why people are advised to lie on their back and float in water, if the get in trouble, as it increases the surface area and buoyancy due to the upward forces? Interesting geological / geochemistry differences given Devon and Somerset are next to each other, how do they contrast with Dorset ?

Yes, but isn't excusive or written as XOR as opposed to OR. for an OR gate?

Just found this course on Futurelearn, which may give some insight into your question https://www.futurelearn.com/courses/justice-fundamental-rights-and-artificial-intelligence Paul

I will try and do some more digging in terms of haemoglobin. In terms of what was mentioned before near the coast | was more thinking of cars rusting due to salt (or rather sea) water ( even though I think it is more corrosion) rather than silver tarnishing, sorry I need to be more clear on things. Re Haemoglobin https://www.tandfonline.com/doi/pdf/10.1179/135100003225002817 Seems to explain the process, with oxygen and haemoglobin, this is a little above me, but I do understand what a REDOX (Reduction and Oxidation) where Reduction is gaining electrons and oxidation loses electrons). Seems quite a complex set of processes going on with this.

Agreed, however it doesn't stop what ever metal you are using reacting with the environment, chrome for example will tarnish, silver does over time, i think more so in salty environments such as near the coast. Am I right in thinking Oxidation is still transfer of electrons (loss) even if this is iron or hemoglobin to oxyhemoglobin in blood. Paul

I am not sure, Mastodon has a feature where if you upload a flyer for example, the alt text generator can take the image and try and extract the text elements (it has mixed results),, So I think the first stage may be just OCR and see what it comes up with, If you can manually edit a few words, that may help, perhaps then run through a spell / grammar check or similar and see what comes from that. If you want the output to be just readable, you don't want AI or anything inserting new words that could easily alter the meaning of the original text. It probably requires manual intervention either way,

So to reply to @studiot I have tried to look up some of the terms / ideas presented above and put my thoughts / interpretations below along with references to where I got the explanation from. * Archimedes Principle. [Archimedes Principle.](https://www.britannica.com/science/Archimedes-principle) covers the laws of buoyancy and states that " that any body completely or partially submerged in a fluid (gas or liquid) at rest is acted upon by an upward, or buoyant, force,"* [1] * Convert [Newtons to grams](https://www.convertunits.com/from/newton/to/gram) * Terzaghi introduced the notion of 'effective stress'. [2] If we apply this to sand then the sand, if placed in a heap (with a slope) needs to have enough strength to stop that slope moving (or as per [2]_ slumping. [2]. Comment, this makes sense, if you're on a beach and try and take the top layer of dry sand and pile this up, it is harder to create a pile, where as digging deeper to the sand that has more firmness (due to water content) can be dug out and piled up, the same goes for making sandcastles, they are likely to stand on their own if the sand is damp and sticks together, nevertheless if you use very wet sand you end up with a similar situation as with the dry sand, it won't keep it's shape. * Contact force, [3] These are forces between two objects * Contact stress [4] I don't fully understand this from reading the source I found. (Don't understand dwell pressure) * Direct (also called normal) force and stress [5] From the source (wikipedia) "In continuum mechanics, stress is a physical quantity that describes forces present during deformation. For example, an object being pulled apart, such as a stretched elastic band, is subject to tensile stress and may undergo elongation. An object being pushed together, such as a crumpled sponge, is subject to compressive stress and may undergo shortening" So I get this, so if I pull something it becomes longer, and I guess weaker as it becomes more elongated, going the other way the stress of compression can also impact. * Tangential or shear force and shear stress ( not indirect or abnormal ), [6] I think I get the principle behind this, so two objects moving against each other. I guess another example is to rip sheet of paper, by holding and pulling in opposite directions causing the paper to be pulled (ripped) apart. Would I be right in thinking that if I try and bolt two materials together that are held in tension, the bolt must be strong enough (tensile strength) to resist the two forces pulling apart that the bolt is holding together. References 1.[Archimedes Principle.](https://www.britannica.com/science/Archimedes-principle) 2 [33.2: Terzaghi's Effective Stress Principle](https://eng.libretexts.org/Bookshelves/Materials_Science/TLP_Library_I/33%3A_Granular_Materials/33.2%3A_Terzaghi's_Effective_Stress_Principle) 3 [Contact force](https://en.wikipedia.org/wiki/Contact_force) 4 [Contact Stress at the Beginning of Demolding[(https://www.sciencedirect.com/topics/engineering/contact-stress) 5 [Stress (mechanics)](https://en.wikipedia.org/wiki/Stress_(mechanics)) - This may not be the correct reference 6 [Shear forces](https://en.wikipedia.org/wiki/Shear_force) Hope this helps Paul

I am not sure what some of these mean exactly, so alongside any explanation here, I am going to do my own digging and research them ( it is kinda expected here after all) it will be interesting to compare findings as they should be the same or very similar explanations ( if I find the right sources). Paul

I was thinking this, as we can pour liquids and also pour a container of Sodium Chloride into a beaker, despite the latter being made of small (granular) particles. With landslides, I usually think of these as being mostly caused by rain fall for example causing the ground to I guess to lose cohesion and move down a hillside or cliff face. We have had this in Dorset, https://www.bbc.co.uk/news/uk-england-dorset-68332305 However, I think these are caused by the area being very dry and collapsing (maybe weight related), the ground also cracks in very dry weather, ( probably the correct term is fissure ) Avalanches (IIRC) are moving snow but are these on top of a pocket of air or is there a sort of air pocket in front of the moving snow. Does the shape of the particles also play a part, I think Salt (NaCl) is cuboid (or at least looking at the structure diagrams it is) graphite is layers so they slide, compared to diamond which is more ridged), Sand appears to be trangular or perhaps pyramid shaped https://chem.libretexts.org/Courses/Honolulu_Community_College/CHEM_100%3A_Chemistry_and_Society/14%3A_Earth/14.02%3A_Silicates_and_the_Shapes_of_Things So maybe this is also a factor in how easy something will move around (even if sold). Paul

This is really important as you said with climate change and changes to agricultural methods we know that insect and bee populations has been seriously reduced hopefully this can be rolled out to reverse some of the damage. Important as we need bees to help grow crops etc. It will be interesting if this can be turned in to an off the shelf product, people could buy at garden centres for example, we know the importance of allowing parts of a garden to grow wild, or plant specific flowers etc to help bees etc, This could give that a boost. Paul

Thanks and good point re article or how it is written. I have undertaken some more digging and found some better links to the research firstly from the Dressel university news page https://drexel.edu/news/archive/2026/March/liquid-breaking-point Secondly to the published paper https://journals.aps.org/prl/abstract/10.1103/t2vy-32wr On Physical review letters Hope fully these help a little more, Paul Would monomolecular layers. refer to Graphene,? which if I understand it is a single layer of carbon atoms, even though this is also an allotropic form of carbon.

Interesting article from 'Interesting Engineering' https://interestingengineering.com/science/scientists-discover-liquids-can-fracture So a simple question on this, what makes a liquid, a liquid in terms of viscosity, given that water is free flowing (if put on a tray and the tray is moved around the water will move around freely). However, if I put cooking oil on the tray and move the surrounding tray requires more tilt to move the oil, (it also depends on friction from the tray I guess (smooth vs rough surface). So do we think about solids and liquids differently ? By fracturing are they suggesting that the bonds in the molecules break or are they referring to the forces that hold the molecules in state where the state would be classed as a liquid. I think oils have long chain, so is it the chain that is pulled for forced apart. Paul

With chemicals such as PFAs is the impact on health based on long term exposure or short term exposure, I think with Asbestos the impact can be felt decades after exposure, but science has known the long term effects for decades (I think) but with newer chemicals surely the long term studies are not there.

You can use Sodium Thiosulfate to clean Silver. Paul What happens if you dilute acetic acid ? So 100ml measuring cylinder, put 10ml of acetic acid and 90ml of water (probably distilled) you then get a 10% solution. Would that make a difference, same would go for Citric acid, which as that can be bought in powder solution you could perhaps make known molar concentrations. Paul

Thanks, this makes more sense now, so the antibiotics in this case would kill any, I guess, dormant virus cells, before they can either move elsewhere or be transmitted to others.

There is current an outbreak of Meningitis B in Kent, United Kingdom, According to the BBC the students are being given vaccines and also preventitive anti biotics. I may be wrong here, but I thought anti biotics are used to treat infections, and not as a preventitive measure (which it what vaccines are for), Am I right here or just not understanding something. Thanks Paul

Thanks for this, if nothing else it confirms there is no right or wrong way as there are multiple conventions, I know things change over time, some are agreed changes, simple things like spelling Sulphur as Sulfur for example Does all the different group conventions make study more challenging or would a university / exam board use one convention.?

I have asked this on Mastodon, as it was related to another post I made there, but I thought I would ask here too Group 4 elements on the @compoundchem@mstdn.social infographic Carbon, Silicon etc, https://www.compoundchem.com/2013/12/29/group-4/ Whereas Wikipedia https://en.wikipedia.org/wiki/Group_4_element Suggests group 4 is Titanium, Zirconium, Most periodic tables are group 1,2 on the left, then there is a jump over the transition to group 3, Boron, Aluminum, Transition element groups are numbered IIIB, IVB (which wikipedia lists as group 4) 2nd group of the transition elements. So which is correct here, or does it depend on the periodic table you are looking at? Paul

This lecture is scheduled for the 28th Feb, but looks interesting s I am sharing here. I have also asked on Mastodon if a recording will be available. AllEventsAstronomy vs The billionaire space race

ScienceDailySchrödinger’s color theory finally completed after 100 yearsA century after Erwin Schrödinger sketched out a bold vision for how we perceive color, scientists have finally filled in the missing pieces. A Los Alamos team used advanced geometry to show that hue,So if we have software that recognizes colour, does this mean that software would need updating to allow for any changes to ideas on how we perceive colour?