#Science #Chemistry #MendeleevNumbers #MaterialProperties
Russian scientists crack Mendeleev mystery
Russian scientists have created a chemical space mapping method and cracked the mystery of Mendeleev Numbers.
Scientists had long tried to come up with a system for predicting the properties of materials based on their chemical composition until they set sights on the concept of a chemical space which places materials in a reference frame such that neighboring chemical elements and compounds plotted along its axes have similar properties.
This idea was first proposed in 1984 by the British physicist, David G. Pettifor, who assigned a Mendeleev number (MN) to each element.
Yet the meaning and origin of MNs were unclear. Scientists from the Skolkovo Institute of Science and Technology (Skoltech) puzzled out the physical meaning of the mysterious MNs and suggested calculating them based on the fundamental properties of atoms.
They showed that both MNs and the chemical space built around them were more effective than empirical solutions proposed until then. Their research supported by a grant from the Russian Science Foundation’s (RSF) World-class Lab Research Presidential Program was presented in The Journal of Physical Chemistry C.
Systematizing the enormous variety of chemical compounds, both known and hypothetical, and pinpointing those with a particularly interesting property is a tall order. Measuring the properties of all imaginable compounds in experiment or calculating them theoretically is downright impossible, which suggests that the search should be narrowed down to a smaller space.
David G. Pettifor put forward the idea of a chemical space in the attempt to somehow organize the knowledge about material properties. The chemical space is basically a reference frame where elements are plotted along the axes in a certain sequence such that the neighboring elements, for instance Na and K, have similar properties.
The points within the space represent compounds, so that the neighbors, for example NaCl and KCl, have similar properties, too. In this setting, one area is occupied by superhard materials and another by ultrasoft ones.
Having the chemical space at hand, one could create an algorithm for finding the best material among all possible compounds of all elements. To build their “smart” map, Skoltech scientists, Artem R. Oganov and Zahed Allahyari, came up with their own universal approach that boasts the highest predictive power as compared to the best known methods.
For many years scientists were clueless as to how Pettifor derived his MNs (if not empirically), while their physical meaning remained a nearly “esoteric” mystery for years.
“I had been wondering about what these MNs are for 15 years until I realized that they are most likely rooted in the atom’s fundamental properties, such as radius, electronegativity, polarizability, and valence. While valence is variable for many elements, polarizability is strongly correlated with electronegativity.
This leaves us with radius and electronegativity which can be reduced to one property through a simple mathematical transformation. And here we go: we obtain an MN that turns out to be the best way to describe all the properties of an atom, and by a single number at that,” explains Artem R. Oganov, RSF grant project lead, a professor at Skoltech and MISiS, a Member of the Academia Europaea, a Fellow of the Royal Society of Chemistry (FRSC) and a Fellow of the American Physical Society (APS).
The scientists used the calculated MNs to arrange all the elements in a sequence that posed as the abscissa and ordinate axes at the same time. Each point in space In corresponds to all compounds of the corresponding elements. In this space, using measured or predicted properties of compounds, one can map any specific characteristic, for example, hardness, magnetization, enthalpy of formation, etc. A property map thus produced clearly showed the areas containing the most promising compounds, such as superhard or magnetic materials
One of the claims made by the #governments of the world to justify imposing the regulations and programmes of a #biosecurity state on their populations is that they are ‘following the science’. By the same token, those who uncritically support these measures — in both #mainstream and social media — claim that anyone who criticises or opposes them are ‘anti-science’.
As #Professor #Levitt states: it is not governments that are following the science; rather, it is #politics that has ‘infected’ the scientists. By making the statements of eminent scientists with the courage to speak out against Government and #media lies more widely known, it is our hope that the debate the people of #Britain should be having will be opened to the knowledge we should be applying to this crisis, which goes far beyond a virus with the fatality rate of a severe #flu, and which threatens the existence of our human rights, civil liberties and democratic politics.
People are insisting on refereed reports. No-one wants to share anything. The #scientists are more panicked and scared of reality than anybody else.
This has got nothing to do with the politics. As a group, scientists have failed the younger generation.
‘Deciding what to do in this situation is really, really difficult. We cannot rely on one or two voices. There should have been a committee formed, either by the Nobel Foundation, by Lindau, by The Royal Society, The National Academy, in the middle of February when this was coming down the road, and we should have discussed this.
‘Instead, we let #economics and #politics dedicate the science.
There was total #panic. And the fact is that almost all the science we were hearing — for example, from organisations like the World Health Organisation — was wrong.
We had Facebook censoring [views contrary to] the World Health Organisation.
Nobody said to me: “Let me check your numbers”. They all just said: “Stop talking like that”.
.. but the fact is that viral cases and deaths follow a time trajectory, and I think that physicist and theoretical chemists who understand trajectories are way better qualified.
‘I am not against #lockdown. I’m against stupid lockdown without considering the full picture. That is, not just combating a
virus that is exactly as dangerous as flu, but also avoiding the economic damage that every country has caused itself, except #Sweden
In other words, everything is data-driven, but people have chosen not to look at the data. In many places, the politics has infected the scientists. Certainly in the USA the politics has infected the scientists.’
‘I think the problem is not just science and public. It’s science to other scientists. Nobody ever said: “You’re saying this: can I check your numbers” This is something which any intelligent person could do themselves in a few days. Every science needs problems to be worked over.
The one place that did have some intelligent #conversation — but I only got involved in it very late — was the European Molecular Biology Lab.
The #criticism is wonderful, because [with]good science, you have to be able to stand up to criticism. Scientists expect to be torn apart. We circled the wagons against this, and it really, really hurt us.’
‘I’m not saying that corona is like flu. But It has exactly the same excess death and age-ranges as flu, and flu is a very serious disease, so I’m not undermining [the existence of] #COVID.
Scientists are arrogant, and refuse to listen to people not in their fields. Scientists are getting away Scott-free for causing billions of dollars’ worth of damage, and this is something which cannot be allowed to happen.
‘It’s not just the World Health Organisation. #Ferguson wanted Sweden to lock down, and got Britain to lock down. And when the numbers become normal, exactly what you would expect without lockdown, he then says: “Ah, it’s because of lockdown”. This is terrible science. This is science which should go on trial. Scientists cannot cause damage like this and refuse to listen.
‘The fact is that #epidemiology and modelling has been a disgrace. They have not looked at the #data. They have been wrong at every turn. We’re going to see that, although coronavirus is a different disease, the net #impact of death is going to be very similar to severe flu. And it’s going to be that way without lockdown.
Scientists in Hawaiʻi have uncovered a glitch in a piece of code that could have yielded incorrect results in over 100 published studies that cited the original paper.
The glitch caused results of a common chemistry computation to vary depending on the operating system used, causing discrepancies among Mac, Windows, and Linux systems. The researchers published the revelation and a debugged version of the script, which amounts to roughly 1,000 lines of code, on Tuesday in the journal Organic Letters.
“This simple glitch in the original script calls into question the conclusions of a significant number of papers on a wide range of topics in a way that cannot be easily resolved from published information because the operating system is rarely mentioned,” the new paper reads. “Authors who used these scripts should certainly double-check their results and any relevant conclusions using the modified scripts in the [supplementary information].”
Luo’s results did not match up with the NMR values that Williams’ group had previously calculated, and according to Sun, when his students ran the code on their computers, they realized that different operating systems were producing different results. Sun then adjusted the code to fix the glitch, which had to do with how different operating systems sort files.
Further inspection revealed that 35,000 litres of sulphuric acid, caustic soda and phosphoric acid were being illegally held in huge 1,000-litre barrels at the the 650-square metre unit. Some 50 propane bottles were also found at the site.Here are some photos from inside the location:
Designing materials from scratch to produce blue is difficult even today, Subramanian says. "So much chemistry has to come together," he says. Subtle changes in the arrangement of neighboring atoms can throw off the energy levels of an atom's electrons, altering the color it can absorb. The red of rubies and the green of emeralds both spring from chromium ions surrounded by six oxygen atoms; other atoms in the two stones cause the color difference by altering the chromium's energy levels. Such effects are very hard to predict, Subramanian says: "If rubies and emeralds did not exist in nature, no one would know how to create them."#Science #Biology #Chemistry #Colours #Blue
But scientists have not given up hunting for new blues, continuing an age-old quest with 21st century tools. Although Subramanian's discovery came about by accident, other researchers are methodically using physics, chemistry, and genetics to find or create new blues for painters to dazzle with, edible colorants that make food more interesting, and blue flowers that, so far, only exist in artists' imaginations.