Cesium is pronounced as SEE-zee-em. Cesium was discovered by Robert Wilhelm Bunsen and Gustav Robert Kirchhoff, German chemists, in through the spectroscopic analysis of Durkheim mineral water. They named cesium after the blue lines they observed in its spectrum. Today, cesium is primarily obtained from the mineral pollucite CsAlSi 2 O 6. Obtaining pure cesium is difficult since cesium ores are frequently contaminated with rubidium , an element that is chemically similar to cesium.
In the earlier study, a group of 24 patients with brain tumors had cesium brachytherapy seeds implanted within the tumors. There were minimal side effects, and it was overall a well-tolerated form of treatment. The idea for using cesium brachytherapy seeds as a treatment for cancer dates back to the s and was described in a study published in the journal Radiology.
A study published in the Journal of Medical Physics , discusses using cesium seeds for treatment in prostate cancer with positive results. And while more research is still needed to understand more about the treatment, all of the studies have shown that using cesium brachytherapy seeds for cancer therapy is encouraging. Mr Lobo is targeting a wide range of clients that all have one thing in common - they need to synchronise a network that operates at speeds far faster than any trains.
Consider for example electricity grids. As wind and solar energy become more widespread, the grid will need to time accurately its reactions to unexpected lulls in the wind or passing clouds. Get that wrong, and you end up with blackouts.
Mr Lobo's biggest target is the financial markets, which these days are dominated by computers programmed to place thousands of trades per second, transmitted down wires at almost the speed of light. In this world, the equivalent of a train crash would be ill-timed bets that rack up millions of dollars in losses, and might even briefly sink the market in the process. Unsurprisingly, financial regulators increasingly require a super-accurate timestamp on every transaction.
But the accuracy of caesium clocks has introduced a potentially disastrous glitch into the world's timekeeping. To understand why, we need to rewind to That year, the official international standard second was redefined based on the caesium transition. Yes, caesium has redefined time itself. The duration of 9,,, periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium atom.
It was a momentous decision. Until then, mankind had always defined time even Railway Time by reference to the movement of the sun relative to the earth.
No more. The sun was dethroned, and caesium took its place - though one wonders how long it will be before strontium or ytterbium knocks caesium off its perch. The switch to atomic time was for good reason. The rotation of the earth, it turned out, was not such a reliable measure of time. No day or year is exactly the same length. First off, the earth is very gradually slowing down and thus the average day is getting infinitesimally longer. Then you have to add in the idiosyncrasies of oceanic tides, tectonic drift and the convection of the earth's mantle, all of which cause minuscule wobbles.
This is a big issue for Felicitas Arias, whose job is to keep time for the entire world. When UTC was first adopted in the s, long before the advent of GPS, it posed a potential problem for sailors, who still relied on clocks to work out their longitude on the high seas. In the late 17th Century, clock and watch design was part of national security.
Navigation and mapping were both essential for the successful conduct of war - and England was involved in a sequence of wars against the French and the Dutch in this period. Lisa Jardine: How the world's first smartwatch was built. They still exploited a system that the super-accurate clocks of another British pioneer of timekeeping, John Harrison, had first made possible in They compared the position of the sun or the stars at their particular location, with the time on a clock taken from another fixed location, typically Greenwich.
Every four minutes' difference represented a single degree east or west. But in order for this technique to continue working, they insisted that UTC remain synchronised with the earth's wobbly rotation.
And that means every now and then an extra "leap second" is inserted. And it is Ms Arias' job to decide when. Then they came back every two or two-and-a-half years. But every time a leap second needs to be inserted, all the atomic clocks across the world need to be changed. Most of us wouldn't notice a second or two every couple of years, but computers do.
They might momentarily shut down, which would, apparently, make them vulnerable to cyber-attack. Or they could get out of sync, leading to electronic train crashes. It hasn't happened yet but Ms Arias believes the consequences could be disastrous. The prospect of City traders losing out on million-dollar deals may not fill you with horror, but she's worried that as power stations, mobile phone networks and satellite navigation systems are increasingly synched to caesium time they could fail too.
Although most ionic lattices consist of an array of larger close-packed anions with smaller cations in the interstices, in CsCl the cesium cations 1.
This leads to a structure that can be described most accurately as simple cubic cesium cations with chlorine anions occupying every eight-coordinate cubic site. This looks analogous to a body-centered cubic structure composed of just one type of atom.
Cesium, like the other alkali metals, readily dissolves in liquid ammonia to produce "solvated electrons" and cesium cations. The solvated electrons possess a characteristic blue color caused by transmitted light and are paramagnetic. At high concentrations the cesium-ammonia solution becomes quite viscous and turns bright gold due to reflected light. On exposure to oxygen, cesium readily forms seven different oxides ranging from Cs 7 O to CsO 3.
Researchers at Bell Labs in the early s reported that doping buckminsterfullerene, C 60 , with the alkali metal potassium led to room-temperature conductivity and low-temperature superconductivity. In collaboration with physics and chemistry colleagues, my group produced the first pure samples of K 3 C 60 and determined the structure to be face-centered cubic C 60 with potassium in all octahedral and tetrahedral sites.
K 3 C 60 has a superconducting transition temperature of To apply "negative" pressure, we replaced K with Rb, which produced an increase in the transition temperature to
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