Cesium is recovered from cesium azide by heating it. Cesium has the second lowest melting point of all metallic elements, which limits its uses. Cesium readily combines with oxygen and is used as a getter, a material that combines with and removes trace gases from vacuum tubes. Cesium is also used in atomic clocks, in photoelectric cells and as a catalyst in the hydrogenation of certain organic compounds.
Since it is easily ionized and has a high mass, cesium ions may one day be used as a propellant in ion engines on spacecraft. Cesium reacts violently with water and ice, forming cesium hydroxide CsOH. Cesium hydroxide is the strongest base known and will attack glass. Cesium is currently being researched in treatment of several forms of cancer, including brain tumors, according to a study published in in the journal Frontiers in Surgery.
Cesium, a radioactive isotope of cesium, is used with iodine, another radioactive isotope, in a brachytherapy seed.
According to the American Brachytherapy Society , a brachytherapy seed is a radioactive pod that is placed directly within the cancerous tissue. Brachytherapy seeds have been shown to be effective in several forms of cancer including prostrate, cervical, and endometrial cancers.
The above study refers to a previous study published in in the Journal of Neurosurgery. 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.
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.
That's why there is a move now to get rid of leap seconds completely and go over to unadulterated atomic time. Most sailors already use satellite navigation, so it might not be such a serious problem for them today as it was in the past. But severing the link between time and the motion of the celestial bodies completely would have some significant consequences.
Because the earth's spin is slowing, the time on your watch would gradually diverge from the rising and setting of the sun. She's surprisingly relaxed about the prospect. She points out that most of us are already out of sync with solar time. Due to the earth's elliptical orbit, the sun can be as much as 16 minutes out of line with mean solar time.
Add the distortion of time zones, which average time across huge regions, and the difference is far greater. China, which is almost 5,km wide, has a single time zone spanning 1h40 of solar time.
The decision of some countries to adjust the clocks twice a year as a "daylight saving" measure exaggerates the issue yet further. Nevertheless many nations resist the move to end leap seconds. The UK, for example, whose Greenwich Meridian was for centuries the benchmark for global timekeeping, insists that leap seconds are not a serious inconvenience. And maybe that is a reasonable position given just how slippery the whole concept of time can be.
In scientists sent three caesium clocks around the world on commercial airliners.
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