Many food producing plants are sprayed with pesticides of some kind. Currently the greatest source of human contamination with these pesticides is on the hand of the people who work in the fields. They come into contact with the plants before they can be washed and depending on the quality of gloves provided the risk of contamination can be high. A new scientific paper has recently been published describing how different brands of gloves often used by amateur gardeners were tested to see how permeable they were to three common pesticides: acetamiprid (C10H11ClN4), pirimicarb (C11H18N4O2) and chlorpyrifos-methyl (C9H11Cl3NO3PS). The conditions these gloves would be under in use was reproduced as best as possible. Chlorpyrifos-methyl was found to pass through latex gloves with ease, penetrating in less than 20 minutes. Although acetamiprid and pirimicarb took a couple of hours to pass through neoprene and latex and all three had a breakthrough time of around 8 hours for butyl gloves. Vinyl and nitrile gloves held back the pesticides for around an hour but the surprising results came from the observations after the gloves had been compromised. Even four days after the original exposure non of the pesticides has been observed exiting the gloves and when the interior was tested the concentration for all three were high. This means that over repeated use the gloves fail and perhaps even make the situation worse holding the pesticides inside. Even water proof gloves are not necessarily pesticide proof and in the future safety information for these gloves should include not only expected breakthrough time but also capacity to hold these chemicals. The importance of educating non occupational plant handlers who might be exposed is also necessary.
Once upon a time I was working with a high power atmospheric laser. To check the beam alignment and where the focal point was I had to hold piece of cardboard in front of the device’s aperture and press a handheld button. A loud bang would occur and the cardboard would turn instantly black. If the mark was a perfect square it meant was in line and the louder the noise the closer to the desired distance I was. At one point I held the cardboard far past the focal point and pressed the button multiple times. It made me jump when the last exposure let out the same massive bang that the perfect one had. It turned out that the heat, gas and vapour given off lensed the laser back into a focal point even at that distance resulting in the shocking noise. I was reminded of this story while planning today’s post, for it is on the focusing and scattering of lasers in free space due to an induced plasma.
Scientists have found that with a strong enough laser the air it moves through becomes ionised. Passing through the produced ions can cause the originally near infra red laser to give off white light that can then scatter further and also diffract based in the plasma’s nature. Understanding this is important as it allows the structure of the plasma to be deduced based on the diffraction pattern produced and also means that this effect can be mitigated in actual experimental or industrial equipment. When the laser is allowed to focus a high pitch noise is heard similar to the bang in my experience. The patterns projected on a screen by this laser are intricate and multichromatic, it seems that the projections are very sensitive perhaps being chaotic in nature meaning the slightest change in parameters can lead to the biggest effect.
In previous posts I have talked about a variety of 2D materials. Black phosphorous, metal dichalcogenides and a whole lot on graphene. Once before I also talked about boron nitride (BN) although referencing its optical properties and brushing over its general crystal layout. The existence of boron nitride (which is often shown as h-BN) as a 2D structure would imply that other nitrides should also exist in 2D, this is at least true for the other chemical groups we have found. But none have ever been discovered. Theory claims there should be other nitride compounds beyond h-BN and they should share many of the same properties, most noticeably a wide band gap of about 4 to 6 electron volts (eV).
This has all changed recently however with the development of 2D gallium nitride (GaN). Since it was so reluctant to form by classical techniques graphene was used as a structure holder while the GaN was grown by slow deposition a couple of molecules at a time. The gallium nitride produced was quite a lot different from the 3D variety. The atomic structure and density of this GaN is experimentally different and varies even from the theoretical prediction. It appears that stabilising 2D nitrides is almost impossible without a foundation of graphene, it may be possible that this is causing the strange results as the material is technically a bilayer structure. Of course a question that could be asked is “if the carbon is required to maintain the the gallium nitride, should it not be counted in the chemical formula in some way?” More experiments need to be done to see if nitrides truly can stand on their own all will always be unstable relying on graphene as crutch.
Currently one profession that takes a massive number of physics graduates is banking. Maths is also highly favoured but the practical understanding that comes with physics is what pushes it slightly above. One of my friends actually attended a recruitment convention just before finishing his degree. Upon meeting two people from the finance sector and telling them he was studying physics and expected a 2:1 he was instantly offered a job in analysis once he finished despite his speciality really being quantum physics. The high proportion of scientists in economics might be an explanation for the trend of absolutism that is currently running through the field. Economics, despite being a wonderful subject, should never be considered a science as it ultimately comes down to human decision. Any field that relies so heavily on a human determinant can not exist in an empirical way. All major economic theories, despite being taken as facts, have failed to prevent financial disasters in the past. Half the challenge is science is working out what isn’t. So beware the absolutist and the soothsayer who claim to know the definite path to the best future, for these people will speak convincing words with conviction nonpareil. But ultimately it is everyone’s duty to learn enough to decide for themselves.
Until tomorrow, goodnight, and keep thinking.
Quantum vacuum fluctuations are one of the most well known concepts of quantum physics. So long as the total energy is conserved between time 0 and time 1, the energy at time 0.5 can actually be different. This can cause pair production of particles which then annihilate and the total energy is the same as that at the beginning. By using a laser pump (named because it pumps more energy into a system, it is in fact just a laser) it is possible to make the vacuum fluctuation produced photons to undergo spontaneous parametric down conversion. This is where the photon produces two new photons that have to share the qualities of the original. This produces squeezing of the photons which I have talked about before.
It has been known for a long time that this squeezing takes a magnitude that is symmetric with half of the frequency of the laser used to pump it. In other words graphically with squeezing against frequency of the laser, reflecting about the frequency axis won’t effect the graph. Now a new result has been found; when a superconducting microwave cavity (a superconducting box permeated by microwave radiation) is pumped, coherence can be achieved between different frequency modes. This means that all the standing microwaves in the box, whatever their wavelength, are all moving up and down in harmony. By changing the qualities of the pumping laser, the quantum fluctuation leading to the photon pairs are altered, and the mode of the waves can be controlled. The ability to engineer quantum vacuums has many possible uses in data storage and computing as well as opening up previously impossible experiments.
The average time a surgically extracted heart can last before being placed back into a body is about five hours. Once all the blood has been drained, the heart is submerged in a solution of between 0°C and 4°C. Using preservatives such as Viaspan and application of machine perfusion (mechanically pumping blood through the organ) the quality of the organs and the suitable time in which they can be transplanted can be improved. But a new discovery has been made that may push the transplant time even further back.
It experiments performed on rats, the extracted hearts were put in an environment of high pressure carbon monoxide (CO) and oxygen (O2) and it was found that even when left between 24 and 48 hours the surgery was a success. There was no noticeable difference between the control group (had hearts that had only just been removed) and the experimental group. The CO is really the key here as it has the ability to delay inflammation, apoptosis and oxidation of the heart’s cells. It also reduces damage caused by reperfusion injury, where the blood flowing back into a deoxygenated sector causes more stress rather than returning the heart to normal functional standards. Even tissue analysis on the hearts of both groups showed there was no difference is cells death or increased risk of heart attack. The simplicity of using a pressurised gas, two commons ones at that, means that this method has a great chance of making serious improvements to the ways in which organs are stored. Perhaps even without the use of excessive technical equipment.
There are four types of nuclear radiation: alpha, beta, gamma and neutron radiation. The first three are the ones most commonly talked about but if asked which is the most damaging most would reply with gamma rays, probably thinking of the Hulk before all else. Their answer is sort of true. If you wanted to be stuck in a room with an emitter of radiation you would probably ask for an alpha emitter. But if you has to ingest the radioactive substance instead your answer should switch to the gamma ray emitter. This is because damage caused by ionising is inversely proportional to the distance these radiation can travel. The more ionising the more likely to ionise the air and be stopped. Gamma is the least ionising but will pass through anything that isn’t a metre of concrete. Alpha is the most ionising but won’t even get through a piece of paper let alone your skin. These effect of these three types of radiation on the body are well understood but what isn’t known is the effect of space radiation.
The radiation in space is of a different breed. Proton and neutron radiation is common along with fast moving heavy ions all together known as high energy particle radiation. Carbon-12, oxygen-16, silicon-28 and iron-56 all cause severe ionisation when passing though the body, even worse then alpha particles (helium-4) due to their much grater mass and charge. A study was performed by exposing mice to the worst offender, iron-56, and seeing what came as a result. It was consistently shown that apart from expected results, like cancer, the mice all seemed to gain weight over the twelve months after receiving the doses. It is believed that the mice have had their leptin producers damaged. Leptin tells the body when it needs to finish eating by inhibiting hunger once consumption begins. It should be noted that the radiation exposure was ten times the expected amount a human would sustain travelling to Mars. So the chances of astronauts gaining considerable weight is unlikely. But we should still be wary of radiation affecting the hormones and other possible illnesses that could result.