Shape-Memory AlloyA shape-memory alloy is exactly what it sounds like: an alloy of two (or more) metals that somehow can “remember” the original shape it was folded into. One of the more famous examples of this is nickel-titanium, or nitinol, will spontaneously fold from a crumpled state back to the ordered, cold forged state when heated. A video of this process can be seen here. This works because of a small phase change in the metal itself, when shaped the atoms arrange themselves into organized crystal structures. Distorting the metal then causes these crystal structures to become disorganized and energetically unfavourable, application of heat then allows the original crystal structure to be formed again by overcoming the energy barrier. The special thing about SMA’s is that the crystal structures can be reversed while in most alloys the structures naturally decay due to diffusion of atoms within the metal.Shape-memory alloys have many applications, ranging from uses in medicine and robotics right through to the more novel, as seen in this lamp designed by Japanese design group Nendo. In this case the heat from the bulb causes the lamp to “bloom” as the strips of alloy move back to their preformed shape.

Shape-Memory Alloy

A shape-memory alloy is exactly what it sounds like: an alloy of two (or more) metals that somehow can “remember” the original shape it was folded into. One of the more famous examples of this is nickel-titanium, or nitinol, will spontaneously fold from a crumpled state back to the ordered, cold forged state when heated. A video of this process can be seen here. This works because of a small phase change in the metal itself, when shaped the atoms arrange themselves into organized crystal structures. Distorting the metal then causes these crystal structures to become disorganized and energetically unfavourable, application of heat then allows the original crystal structure to be formed again by overcoming the energy barrier. The special thing about SMA’s is that the crystal structures can be reversed while in most alloys the structures naturally decay due to diffusion of atoms within the metal.

Shape-memory alloys have many applications, ranging from uses in medicine and robotics right through to the more novel, as seen in this lamp designed by Japanese design group Nendo. In this case the heat from the bulb causes the lamp to “bloom” as the strips of alloy move back to their preformed shape.

Siderophores

Iron is one of those things that life needs, it’s at the heart of many proteins such as the hemoglobin in your blood. But getting that sweet, sweet ferrous metal is not always so easy. That’s why many creatures have evolved to use special chemical compounds known as siderophores (Greek for iron carrier). Siderophores are produced within the cell and then released into the extracellular environment where they bind to iron ions, helping to solubilize them and thus transfer them into the cell. Enterobactin (pictured above) is a particularly potent siderophore that works somewhat like the claw in one of those games where you try and retrieve a stuffed animal. In this case the oxygen atoms surround and bind to the iron atom to form metal-ligand bonds.

Materials That Fix ThemselvesThe quest for a self-repairing material has been an on going one, for years chemists have dreamed of being able to artificially recreate something that seems so trivial in biology. Now a team at the University of California, San Diego have achieved that using hydrogels. Hydrogels (or aquagels) are hydrophilic polymers which are highly absorbent and have a degree of flexibility very similar to natural tissues, allowing them to be prime components of tissue scaffolding. By manipulating the side chains of the constituent polymers, UCSD scientists have managed to achieve polymers that once broken can rejoin or “heal” by latching on to one of these “dangling” side chains.Image

Materials That Fix Themselves

The quest for a self-repairing material has been an on going one, for years chemists have dreamed of being able to artificially recreate something that seems so trivial in biology. Now a team at the University of California, San Diego have achieved that using hydrogels. Hydrogels (or aquagels) are hydrophilic polymers which are highly absorbent and have a degree of flexibility very similar to natural tissues, allowing them to be prime components of tissue scaffolding. By manipulating the side chains of the constituent polymers, UCSD scientists have managed to achieve polymers that once broken can rejoin or “heal” by latching on to one of these “dangling” side chains.

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Soap Films and the Minimal Surface

One subject of particular interest to me is soap films, while they hold wonder for children they’re also amazing in scientific terms. The  shape and structure of a soap films is determined by what configuration minimizes surface area, this is why bubbles are round. However other interesting shapes known as minimal surfaces arise such as the catenoid and helicoid. The catenoid is the shape formed by rotating a caternary around it’s axis of symmetry, the catenary in turn is the shape formed by a hanging chain. The helicoid is a minimal surface that can be formed from a catenoid without any deformation or stretching. Both of these shapes (along with the plane) have zero mean curvature and also minimize surface area and as such are energetically favorable shapes for soap films (with boundaries) to exist in.

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Chemistry on ComputersOne of the most lengthy components of chemistry is all that trial and error to find out exactly how to make the chemical you want, or even just to assess the chemical properties once you have made a chemical. The problem is, there simply isn’t a way to predict how a molecule will behave. Until now. Computer scientists have recently developed an algorithm which can predict certain features of a molecule based off other examples. While this doesn’t give exact answers they found that by using 1000 examples they could calculate the atomization energies of over 6000 other molecules to a precision of 1%. The major problem that had been facing this “designed” approach had lay in the complexity of chemistry equations, most notably the Schrödinger equation which can only be solved efficiently and accurately for 1 electron systems. Instead this Machine Learning approach, which has been used in stock markets for years, gives approximations accurate enough to find what you need to know. As such, research that previously took years may be able to be completed in a fraction of the time.Image

Chemistry on Computers

One of the most lengthy components of chemistry is all that trial and error to find out exactly how to make the chemical you want, or even just to assess the chemical properties once you have made a chemical. The problem is, there simply isn’t a way to predict how a molecule will behave. Until now. Computer scientists have recently developed an algorithm which can predict certain features of a molecule based off other examples. While this doesn’t give exact answers they found that by using 1000 examples they could calculate the atomization energies of over 6000 other molecules to a precision of 1%. The major problem that had been facing this “designed” approach had lay in the complexity of chemistry equations, most notably the Schrödinger equation which can only be solved efficiently and accurately for 1 electron systems. Instead this Machine Learning approach, which has been used in stock markets for years, gives approximations accurate enough to find what you need to know. As such, research that previously took years may be able to be completed in a fraction of the time.

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Show Us What You’re Made Of!

The word “protein” is a fairly house hold term, but it seems to me that most people don’t actually know what it is to any level greater than “oh that thing in food that makes you strong!”. A protein is basically a polymer made of amino acids pictured is a basic structure), in humans (and all eukaryotes) proteins are made up from 21 types of amino acids, although the actual number of amino acids is fairly innumerable. Proteins are created at ribosomes within the cell and are coded for by mRNA which is essentially a copy of DNA. The amino acids are transported by tRNA which matches to the mRNA and thus creates the order of amino acids. It is this order which governs the shape of the protein and thus its function, as such small mutations in the DNA can be disastrous such as in sickle cell anemia. Proteins fold due to hydrophobic forces created by side chains (which would be where the R is in the diagram) of the amino acid and are stabilized due to things such as hydrogen bonds. These proteins then go on to make up a large number of structures in your body, from the enzymes that digest your food, to the protein channels that regulate the flow of chemicals in and out of your cells and right down to the haemoglobin in your blood supplying you with oxygen. The protein pictured here is known as the Green Fluorescent Protein and is what is responsible for all those genetically engineered “glow in the dark” animals.

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Ever wondered what flavors look like? Here you go!

Each one of these shows some chemical present in your every day food that contributes to the flavors you know and love seen through the microscope!

Top: capsaicin from chillis
Middle: glucose (sugar), catechin (present in teas) and honey
Bottom: some stuff from strawberries and lettuce!

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Hydrogen Bonding

Hydrogen bonding is a common “force” in nature, it’s what holds your DNA and proteins together and what makes water so weird and wonderful. Without it you wouldn’t be you, in fact you probably wouldn’t be anything. Hydrogen bonds are both inter and intra molecular forces in that it can act between different molecules (in the case of DNA bases) or within the same molecule (such as single chain proteins). Hydrogen bonding arises from polarity within a molecule, for this to happen a hydrogen must be bonded to an electronegative atom such as oxygen, fluorine or nitrogen (or be part of something like CHCl3). This causes the probability of an electron being around the hydrogen to decrease thus leaving it with a partial positive charge whilst the electronegative species has a slight negative charge. The slightly positive hydrogen is then attracted to other electronegative atoms that neighbor it. This causes an attractive force between them and gives an organized structure such as the crystalline form of ice or the hexagonal shape of a snowflake.

Fluorite

Fluorite is a mineral composed of calcium fluoride (CaF2) and aside from having a cool cubic structure also comes in a variety of different colours. The coolest thing about fluorite however is that it fluoresces under ultraviolet radiation. In fact the very word fluoresce comes from this mineral (fluo in latin originally means “to flow” and was given to fluorite because of its uses in iron smelting). However the fluorite itself is not the thing doing the glowing but rather impurities within its crystal structure such as yttrium, europium (which is pictured) or small organic compounds. These and other impurities also give fluorite its diverse range of colours, leading it to be dubbed the “most colourful mineral in the world”. The mechanism of fluorescence is that UV radiation is absorbed by excitation of electrons into higher energy levels. These excited electrons then fall back to the ground state and emit energy in the form of a photon of visible light in the process.

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Electroplating

So I mentioned batteries the other day and thought I should follow up with a bit more electrochemistry. Electroplating is simply the act of using an electrical current to deposit a layer of one thing (usually a metal) on top of another thing. This is fairly common procedure for many things including making car parts and taps shiny by depositing a layer of chromium. In electroplating the object to be covered is located at the cathode (the negative end) and must be electrically conductive. Another electrode is also needed and in some cases is made of the material to be deposited. Both these electrodes are then placed in a solution containing dissolved metal salts (such as copper sulfate). The ions in this solution allow the flow of an electrical current along with providing the metal necessary to coat the cathode. When this system is switched on the dissolved metal ions move towards the cathode and begin to adhere to the surface. This is because the positive charge on the metal ion is removed by the addition of electrons from the power source. This turns the water soluble ionic metal into the non soluble solid metal we all know, coating the cathode in the process. This continues until all the metal ions in the solution are used up or the current can no longer flow. In cases where the anode is made of metal it may also begin to dissolve as it attempts to make up for the ion imbalance in the solution, thus it reduces in mass and itself can transfer to the cathode.

Electroplating can also lead to fractals as seen in the SEM image.


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oblivioncontinuum: Glowsticks: how do they work? The emission of light is the only physics principle involved here, but the chemistry isn’t that hard to understand the basis of. Glowsticks work by mixing two compounds, typically hydrogen peroxide and a phenyl oxalate ester. The hydrogen peroxide is kept in a separate glass tube, which is broken when the glowstick is bent. The ester is then oxidized by the hydrogen peroxide, which creates a chemical called phenol and an unstable peroxyacid ester. That peroxyacid ester decomposes and additional phenol is released amongst a cyclic peroxy compound, which decomposes into carbon dioxide. This decompostion releases a substantial amount of energy, which is not observed without the presence of a fluorescent dye. Moving on. The dye is the component capable of chemiluminescence, which is why light is not emitted without it. When the energy from the decomposing cyclic peroxy compound is transferred to the dye, the electrons are temporarily excited into a higher energy level and when they eventually fall back to the ground state, the loss of energy of the electron is released as a photon. The colour, or frequency of this photon depends on how much energy it is released with. The higher the energy, the further toward the violet end of the spectrum the light emitted will be. Different dyes rely on different amounts of energy to excite electrons, which is why other frequencies are emitted.  The speed and intensity of the reaction is dependent on the chemicals used, but also the temperature. Putting a glowstick in the freezer slows the atoms’ collisions down, therefore releasing less energy over the same amount of time which causes less photons to be emitted. However, the reaction lasts a lot longer. The opposite is true for higher temperatures, where the light is brighter, but the glowstick won’t last as long. In conclusion, glowsticks are really cool.

oblivioncontinuum:

Glowsticks: how do they work?

The emission of light is the only physics principle involved here, but the chemistry isn’t that hard to understand the basis of. Glowsticks work by mixing two compounds, typically hydrogen peroxide and a phenyl oxalate ester. The hydrogen peroxide is kept in a separate glass tube, which is broken when the glowstick is bent. The ester is then oxidized by the hydrogen peroxide, which creates a chemical called phenol and an unstable peroxyacid ester. That peroxyacid ester decomposes and additional phenol is released amongst a cyclic peroxy compound, which decomposes into carbon dioxide. This decompostion releases a substantial amount of energy, which is not observed without the presence of a fluorescent dye. Moving on.

The dye is the component capable of chemiluminescence, which is why light is not emitted without it. When the energy from the decomposing cyclic peroxy compound is transferred to the dye, the electrons are temporarily excited into a higher energy level and when they eventually fall back to the ground state, the loss of energy of the electron is released as a photon. The colour, or frequency of this photon depends on how much energy it is released with. The higher the energy, the further toward the violet end of the spectrum the light emitted will be. Different dyes rely on different amounts of energy to excite electrons, which is why other frequencies are emitted. 

The speed and intensity of the reaction is dependent on the chemicals used, but also the temperature. Putting a glowstick in the freezer slows the atoms’ collisions down, therefore releasing less energy over the same amount of time which causes less photons to be emitted. However, the reaction lasts a lot longer. The opposite is true for higher temperatures, where the light is brighter, but the glowstick won’t last as long. In conclusion, glowsticks are really cool.

New ‘smart’ nanotherapeutics send drugs directly to the pancreas

bloodredorion:

Although it will need to be further tested before being ready for clinical use, it could potentially improve treatment for Type I diabetes.


The approach was found to increase drug efficacy; it is concentrated at target sites, such as regions of the pancreas that contain the insulin-producing cells.

The dramatic increase in efficacy also means that much smaller amounts of drugs would be needed for treatment, opening the possibility of significantly reduced toxic side effects, as well as lower treatment costs.

Using nanoparticles that can be programmed to deliver drug or stem cell therapies to specific disease sites is an excellent alternative to systemic treatments because improved responses can be obtained with significantly lower therapeutic doses and hence, fewer side effects.

Mayonnaise

Not all the knowledge I have is useful. For example I can tell you that mayonnaise was invented 4 years before the sandwich (which was invented by the now hilariously named Earl of Sandwich) in 1756. I can also tell you the deep mysteries of mayonnaise function. At its simplest all mayonnaise is oil, vinegar (or lemon juice) and a little bit of egg. As you can imagine though vinegar and oil don’t get on very well and instead like to separate. So how do we go from two relatively disgusting separated compounds to the deliciousness that is mayonnaise? Mayonnaise exists as a colloid, which is simply a mixture of two things which don’t dissolve in each other and don’t separate out over time, in this case oil in vinegar. What stops them from otherwise separating is located in the egg yolk. The compound in question is known as lecithin which is pictured on the right, while on the left we have a scanning electron microscope image of frozen mayonnaise. Lecithin has two features of interest, firstly it’s a polar molecule and secondly it has a long carbon chain. This is useful because it means that the carbon chain can integrate and become embedded in the droplets of oil. The positive charges at the opposite end then repel each other and so prevent the oil droplets from coming together and coagulating. In this sense the lecithin behaves as an emulsifier.

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