Yearly Roundup 1

Well it has been a very unique year. 2016 will go down in history as a year with a lot of controversy and a spree of tragic celebrity deaths, but hopefully some fortunate things as well. If a recount all the main physics stories was required the most major must be the discovery of gravitational waves. This is perhaps the most phenomenal revelation of the decade and so certainly makes it top of the year. The naming of the four new elements is certainly something we don’t get very often and so is probably worth a mention. In the field of biophysics there was the very first baby born with the DNA of three people in order to prevent the child inheriting an hereditary disease. The “special particle” in the large hadron collider was definitely news but maybe not for the right reasons but there was the announcement of the tetraquark family that was discovered when old data was re-examined. JUNO finally managed to reach its destination of course and in other astrophysics news there was the discovery of a plausibly inhabitable planet near alpha centurai and possibly my favourite but least talked about stories of all: Scientists have designed a solar sail powered spaceship just a couple of centimetres long. It has the capability to to travel at between 15% and 20% the speed of light and so could make it to the local centurai stars in about 20 to 30 years. Just the message they would send back would take 4 years to reach us but it would be the first human contact with another star. I almost become starry eyed thinking about it myself.

So even though it may seem all gloomy and the doom callers seem to be finally getting it right, there’s still a lot of positive things going on. No matter how everyone else is going to remember this year I will always remember it as both the year I started this blog and also a year of spectacular scientific achievement. So, until tomorrow, and I must say this has been a long time coming, good night and happy new year.

Sneaking Sulphur Species Into The Body

Chemists have great skill when it comes to knowing what chemicals will be given off in reactions and how these will interact with already present chemicals and so on. For instance if a lot of a halogenoalkane like methane chloride (CH3Cl) reacts with ammonia (NH3) then quite simply the whole CHthat was attached to the Cl previously replaces one H on the NH3. This leaves hydrochloric acid (H+Cl from the removed parts) and methylamine (CH3NH2). But since there is still CH3Cl present it can react and replace another hydrogen on the nitrogen. This happens again and again until you are left with:

Tetra methyl ammonium chloride (thank you to the University College of London for this image)

So the main puzzle that gets created for biologists is how do they make  a useful reaction occur where they want it. The chemical they want delivered is hydrogen sulphide (H2S) as in small quantities it can help reduce oxidation in cells. Hydrogen sulphide is the chemical that makes rotten eggs spell so bad and generally when the human body has evolved to be repelled by something you really don’t want to go near it. Anyone who has encountered H2S in a pure form will know the safety procedures necessary and so to get it into the body safely is a challenge. To perform this feat the scientists noticed that when human cells are under oxidised stress, species like hydrogen peroxide (H2O2) are formed. The solution is to build  a specific biological molecule that contains carbonyl sulphide (COS, which rapidly is converted into H2S by the body) and then releases the COS when a trigger molecule, like the hydrogen peroxide, reacts with it. It is still unclear how well this method will work in vivo practice but in laboratories results already seem promising.

Recording Star Reverberations

Stars have been a common subject over the last year primarily because there are many parts of astrophysics that are still a mystery. The brilliant thing about astronomy is that it is a part of physics that anyone can take part in. Even the most amateur astronomer can use basic photometry to  learn something about an observed object. Photometry is just recording the brightness of an object over a period of time. If an object dims it is probably because something is moving across it and blocking out some of the light. If a star is being observed its probably an exoplanet and if it is another planet in our solar system dimming it must be one of their moons. Professional photometry isn’t performed from the ground (and when it is its normally done on top of mountains in the Bahamas or the like) it is usually done from telescopes positioned in space. The most famous of these, The Kepler Space Telescope, has been recording the brightness of a white dwarf for three months (exactly 78.7 days).

This star has only half the mass of The Sun but five times the surface temperature and has an almost complete helium atmosphere. This means that it is actually a variable star with a constantly changing luminosity, the hottest white dwarf that has ever been recorded to pulsate. By observing a change in luminosity, probably brought about by a solar spot, the rotation of the white dwarf was also calculated to be about 10.2 hours. This star also demonstrates some unique astroseismology, the equivalent to earthquakes for a star. Standing waves form inside the star’s plasma and these oscillating modes can reveal details about the star’s internal structure. This white dwarf, however, contained eleven completely independent modes which allow researchers check on their rotation estimate. This information goes into a growing database focused on answering the questions of stellar evolution one of the many things that astrophysics still needs to work out.

Self Casting Ceramic Shapes

Ceramography is the study of how to create and prepare ceramics. Ceramics are non metallic solids formed from either metallic or non metallic compounds which are shaped and then heated to harden. Despite their infamy for being brittle they are very hard materials with a high strength and are very difficult to fracture. They are tough enough to be used in some ballistic vests in order to slow or stop a bullet. Ceramics ability to conduct heat well and a good resistance to wear is why they are used in car brakes and coated on to jet turbines. Their electrical properties also mean that ceramics can make good dielectrics in capacitors. There have even been laboratory models made of a car engine made completely of ceramic that requires no cooling and won’t wear down overtime. The problem is that small cracks can easily develop and so mass production isn’t feasible yet.

Many of these uses required the ceramics to be in a specific shape at quite a small size. Normally to create such intricate models injection moulding or another top down fabrication method is used. After being created the parts are then dryed and sintered. Since the shape is already set this step can be hazardous as the heat can distort the ceramics, especially multiple layer ceramics, and cause internal cracks as some layers expand faster then others. But a new idea has been suggested to get around this try to make the ceramics form their shape during the sintering step. Taking inspiration from how plant fibres can self distort alumina (Al2O3) pigment were set up inside the ceramic as to control the rate of shrinking when heated. This method doesn’t require any extra equipment, minimises waste material and reduces the risk of micro fractures occuring. This method should also hopefully be applicable to glass formation   and it is theorised that it might be able to manipulate ceramics and glasses up to a scale of a couple of centimetres. With development this research should be able to create new designs and geometries which are currently unavailable to modern engineering.

Theoretically True Topological Photonics

Topological insulators are materials in which the electrons can only move along the surface while the core remains an insulator. In some unique circumstances when superconductivity is induced the electrons can move without any interference even when impurities are present in the insulator. Using the infamous logic: “If it works for particles, why not waves” the study of topological photonics was created. Through meticulous design, materials can be created that interact with light in very unique ways using topological mathematics as a base. These materials are exclusively 2D existing only as a single scattering layer for the light. One of the most interesting discoveries was that much like the electrons, the photons were willing to bypass any impurities that would normally cause them to be reflected. Light’s behaviour in these materials has greatly developed our ideas about electromagnetic interactions in solids relating to both their transmission and scattering. The disadvantage being that there is only so much that can be done when your working in only two dimensions.

However a recent paper has shown that it is at least theoretically possible to create a 3 dimensional topological system if it is created inside a dielectric material. This insures that the electric and magnetic field interact in such a way to produce a synthetic gauge field, an effective field which is produced by the  Lorentz force and the Coriolis force (which is in itself imaginary), which causes Electrons to begin to display Dirac distributions. Now that it has been shown to be plausible that 3D photonic topologies can be created it is now just a question of how to manufacture one and if it was to be manufactured what effects would it demonstrate.

Combining Effects To Effectively Convert Heat

Efficiency is a very important thing. It is simply the amount of energy that is used for the intended purpose compared to the amount that is put in to the device. Electric radiators are probably the most efficient things you’ll find as almost all the energy put into them gets converted into heat. Light bulbs are some of the most inefficient devices for the exact same reason, almost all the energy gets converted into heat when really we want light. Although sound is occasionally a factor loss into heat is always present as any friction or air resistance slows any moving things whether they be electrons in a wire or balls in the air.

There is something called a transverse thermoelectric device which when heated produce electric fields at a right angle to the direction of incoming heat due to the temperature gradient. This is related to the Nernst effet where a material is heated under a magnetic field and so an electric field forms as the electrons become thermally excited and are acted upon by the magnetic field. The spin Seebeck effect is where two points of different temperature in a magnet cause a spin current (flow of spin up electrons) to form which then induces itself in a non magnetic metal placed nearby. The spin current is converted by the Hall effect into a voltage difference so a direct current flows.

It has been shown that it is possible to combine Nernst effect and spin Seebeck effect in macromaterials such as conducting magnets made from nickel or bismanol (Ni and MnBi) containing nanoparticles of gold or platinum (Au and Pt) which both have strong spin orbits. These materials showed a great ability to convert heat, the kind that would normally be wasted, into electricity by using both of these effects with the nickel platinum combination being the most effective. This not only proves the spin Seebeck effect is present beyond the thin films it normally operates in but also provides at least a theoretical  improvement to many electronic devices.

Weekly Roundup 51

Well this is it, the last weakly roundup before the new year and landing on Christmas day as well. As I predicted the science news has all but ceased for the holidays. I was however quite impressed with the story about the lightening photography and the one about pack evolution. Both of these topics are far flung from my own expertise as are many of the things I have written about over the course of the year. Looking at my first set of posts I am glad to see that over the year my style and content has improved where at the beginning I would average about 100 words I now often write over 300 on any post. I have also (basically) managed to achieve my goal to do one post every day as my statistics page tells me I have published 352 (which will soon be 353) posts and there have currently been 359 days past in this year. Luckily the numbers are bolstered by the pages I have written on the non-news topics. Overall I am very proud of what I have archived and I would tell you what my plans are for the next year but I have a special post planned out for that.

Anyway, I hope everybody has a lovely Christmas day and until tomorrow, goodnight.