Ultra-thin slices of diamonds reveal geological processes

Diamonds are not only beautiful and valuable gems, they also contain information of the geological history. By using ultra-thin slices of diamonds, Dorrit E. Jacob and her colleagues from the Macquarie University in Australia and the University of Sydney found the first direct evidence for the formation of diamonds by a process known as redox freezing. In this process, carbonate melts crystallize to form diamond. The slices were prepared by Anja Schreiber of the GFZ German Research Centre for Geosciences in Potsdam, Germany. The work is published in Nature Communications. The study shows that the reduction of carbonate to diamond is balanced by the oxidation of iron sulphide to iron oxides.

Siberia's Udachnaya diamond mine, by Stepanovas (Stapanov Alexander). (Own work) [GFDL (http://www.gnu.org/copyleft/fdl.html) or CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/)], via Wikimedia Commons

The researchers used the new nano-scale technique of Transmission Kikuchi Diffraction to discover rims of the iron oxide mineral magnetite just a few ten thousandths of a millimetre thick around sulphide minerals inside the diamonds. The GFZ's Anja Schreiber prepared these slices using a focussed beam of charged atoms (ions) to ablate the surface. The already ultra-thin slices were re-thinned after being mounted on a carbon-coated copper grid. This process was carried out for the first time successfully on a grid and yielded the data set used for the study.

The results also solve a puzzle that has occupied diamond researchers for decades, namely the over-abundance of sulphide occurring as inclusions in diamond. Iron sulphides are the most common inclusions in diamond even though there is only about 0.02% of sulphur in the mantle: it now appears that the oxidation of the iron sulphides directly causes the formation of the diamonds that include them.

For more information visit:-

https://www.sciencedaily.com/releases/2016/06/160621115443.htm

http://www.prlabs.co.uk/lab-supplies.php?N=dimethyl-sulphide-for-synthesis&Id=36347

ExoMars: 'giant nose' to sniff out life on Mars prepares for launch

Space engineers are making final preparations for the launch of a robot spacecraft designed to sniff out signs of life on Mars.

The probe, ExoMars 2016 – the first of a two-phase exploration of the Red Planet by European and Russian scientists – is scheduled to be blasted into space on a Proton rocket from Baikonour cosmodrome in Kazakhstan at 0931 GMT on Monday.

The spacecraft consists of a module called Schiaparelli that will test heat shields and parachutes in preparation for future probe landings on Mars and a second main component, the Trace Gas Orbiter or TGO, that will analyse the planet’s atmosphere. In particular it will seek out the presence of the gas methane which, on Earth, is produced by living organisms.

“Essentially our spacecraft is a giant nose in the sky,” said Jorge Vago, an ExoMars project scientist based with the European Space Agency (Esa). “We are going to use it to sniff out the presence of methane on Mars and determine if it is being produced by biological processes.”

Methane is normally destroyed by ultraviolet radiation within a few hundred years of its creation. Its presence on Mars would therefore suggest life had recently been active there. The US robot rover Curiosity, which landed on Mars in 2012, initially found no sign of methane. Subsequent analyses in 2014 did report the presence of methane in the Martian atmosphere in one area. However, some scientists have argued that it may have been created by non-biological means.

On Earth most methane is generated biologically, but it can be made by chemical processes under the surface. To differentiate between these two processes, the ExoMars trace gas detector will not only analyse methane levels in more detail than any previous mission but also study other gases that will provide information about its likely source. “If methane is found in the presence of other complex hydrocarbon gases, such as propane or ethane, that will be a strong indication that biological processes are involved,” said another project scientist, Manish Patel, of the Open University.

“However, if we find methane in the presence of gases such as sulphur dioxide, a chemical strongly associated with volcanic activity on Earth, that will be a pretty sure sign that we are dealing with methane that has come from the ground and is a byproduct of geological processes.”

By NASA, ESA, and The Hubble Heritage Team (STScI/AURA) [Public domain], via Wikimedia Commons

ExoMars is expected to arrive at the Red Planet on 19 October after a journey of 308m miles (496m km) across space, and will be followed by a second ExoMars mission, a Mars rover, scheduled for launch in 2018 – although Esa officials have warned that it may be delayed by budget problems.

On Friday, Russian engineers completed the rollout of the giant Proton rocket that will carry ExoMars to its destination, and on Saturday, staff at Esa’s mission control centre in Darmstadt, Germany – which will run the mission once in space – conducted a dress rehearsal for the launch. “We do a similar dress rehearsal for every launch,” said Paolo Ferri, head of mission operations for Esa. “It’s a milestone that caps off several years of preparation for any complex mission – designing, building and testing the ground systems, preparing the flight operations procedures and then finally an intensive period of team training.”

Finally, on Monday, the spacecraft is scheduled take off from Baikonour. Then, when it has reached orbit, the TGO, still linked to the Schiaparelli test lander, will separate from the fourth stage of its Proton launcher and begin its seven-month journey to the Red Planet.

For more information, visit:-

https://www.theguardian.com/science/2016/mar/13/exomars-giant-nose-life-on-mars-prepares-launch

http://www.prlabs.co.uk/lab-supplies.php?N=bisdiphenylphosphino-methane-for-sy&Id=38134

On this day in history: Krakatoa erupted

In 1927, Krakatoa began a new volcanic eruption on the seafloor along the same line as the cones of previous activity. By 26 Jan 1928, a growing cone had reached sea level and formed a small island called Anak Krakatoa (Child of Krakatoa). Sporadic activity continued until, by 1973, the island had reached a height of 622 ft above sea level. It was still in eruption in the early 1980s. The volcano Krakatoa is on Pulau (island) Rakata in the Sunda Strait between Java and Sumatra, Indonesia. It had been quiet since its previous catastrophic eruption of 1883. That threw sulphur and pumice 33 miles high and 36,380 people were killed either by the ash fall or by the resulting tidal wave. The only earlier known eruption was in 1680, and was only moderate.

Volcano, by ISS Crew Earth Observations experiment and the Image Science & Analysis Group, Johnson Space Center. [Public domain], via Wikimedia Commons

The combination of pyroclastic flows, volcanic ash, and tsunamis had disastrous results in the region. There were no survivors from the 3,000 people located on the island of Sebesi, about 13 km (8.1 mi) from Krakatoa. Pyroclastic flows killed around 1,000 people at Ketimbang on the coast of Sumatra some 48 km (30 mi) north from Krakatoa. The official death toll recorded by the Dutch authorities was 36,417, although some sources put the estimate at 120,000 or more. Many settlements were destroyed, including Teluk Betung (Bandar Lampung), and Sirik and Serang in Java. The areas of Banten on Java and Lampung on Sumatra were devastated. There are numerous documented reports of groups of human skeletons floating across the Indian Ocean on rafts of volcanic pumice and washing up on the east coast of Africa, up to a year after the eruption. Some land on Java was never repopulated; it reverted to jungle, and is now the Ujung Kulon National Park.

Ships as far away as South Africa rocked as tsunamis hit them, and the bodies of victims were found floating in the ocean for months after the event. The tsunamis which accompanied the eruption are believed to have been caused by gigantic pyroclastic flows entering the sea; each of the four great explosions was accompanied by massive pyroclastic flows resulting from the gravitational collapse of the eruption columns.This caused several cubic kilometers of material to enter the sea, displacing an equally huge volume of seawater. The town of Merak was destroyed by a tsunami 46 m (151 ft) high. Some of the pyroclastic flows reached the Sumatran coast as much as 40 km (25 mi) away, having apparently moved across the water on a cushion of superheated steam. There are also indications of submarine pyroclastic flows reaching 15 km (9.3 mi) from the volcano.

Smaller waves were recorded on tidal gauges as far away as the English Channel. These occurred too soon to be remnants of the initial tsunamis, and may have been caused by concussive air waves from the eruption. These air waves circled the globe several times and were still detectable on barographs five days later.

For more information visit:-

http://www.todayinsci.com/12/12_29.htm

https://en.wikipedia.org/wiki/1883_eruption_of_Krakatoa

https://www.prlabs.co.uk/lab-supplies.php?N=sulphur-1000ppm-for-icp&Id=60224

On this day in Science History: The Last Fragments of Comet Shoemaker-Levy Struck Jupiter

In 1994, the last of the large fragments of the comet Shoemaker-Levy struck Jupiter (Fragment W).

This was a comet that broke apart, colliding with Jupiter and providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its role in reducing space debris in the inner Solar System.

"Shoemaker-Levy 9 on 1994-05-17" by NASA, ESA, and H. Weaver and E. Smith (STScI) - http://hubblesite.org/newscenter/archive/releases/1994/26/image/c/ (direct link). Licensed under Public Domain via Wikimedia Commons 

The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy.  Shoemaker–Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the 40 cm (16 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by the planet around 20 – 30 years earlier. 

Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull apart the comet. The comet was later observed as a series of fragments ranging up to 2 km (1.2 mi) in diameter. These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 km/s (37 mi/s) or 216,000 km/h (134,000 mph). The prominent scars from the impacts were more easily visible than the Great Red Spot and persisted for many months.

Observers hoped that the impacts would give them a first glimpse of Jupiter beneath the cloud tops, as lower material was exposed by the comet fragments punching through the upper atmosphere. Spectroscopic studies revealed absorption lines in the Jovian spectrum due to diatomic sulfur (S2) and carbon disulfide (CS2), the first detection of either in Jupiter, and only the second detection of S2 in any astronomical object. Other molecules detected included ammonia (NH3) and hydrogen sulfide (H2S). The amount of sulfur implied by the quantities of these compounds was much greater than the amount that would be expected in a small cometary nucleus, showing that material from within Jupiter was being revealed. Oxygen-bearing molecules such as sulfur dioxide were not detected, to the surprise of astronomers.

As well as these molecules, emission from heavy atoms such as iron, magnesium and silicon was detected, with abundances consistent with what would be found in a cometary nucleus. While substantial water was detected spectroscopically, it was not as much as predicted beforehand, meaning that either the water layer thought to exist below the clouds was thinner than predicted, or that the cometary fragments did not penetrate deeply enough. The relatively low levels of water were later confirmed by Galileo's atmospheric probe, which explored Jupiter's atmosphere directly.

For more information visit:-

https://en.wikipedia.org/wiki/Comet_Shoemaker%E2%80%93Levy_9

http://www.todayinsci.com/7/7_22.htm

http://www.prlabs.co.uk/lab-supplies.php?N=sulphur-1000ppm-for-icp&Id=60224

http://www.prlabs.co.uk/lab-supplies.php?N=iron-1000ppm-for-icp&Id=60140

http://www.prlabs.co.uk/lab-supplies.php?N=magnesium-1000ppm-for-icp&Id=60155

Antimony

Antimony is a chemical element with symbol Sb (from Latin: stibium) and atomic number 51. A lustrous grey metalloid, it is found in nature mainly as the sulfide mineral stibnite (Sb₂S₃).

 

Antimony compounds have been known since ancient times and were used for cosmetics.  Nowadays Antimony is mainly used as its trioxide in making flame-proofing compounds and in certain alloys.  The Egyptians had a hieroglyph for Antimony......

Antimony has no known biological role, but it is a potent toxin, with effects that are similar to arsenic poisoning. When ingested, antimony strongly bonds to sulfur-containing enzymes, thereby inactivating them. Antimony is even more toxic when inhaled as the gas, stibine, SbH₃. Poisoning by antimony ingestion manifests as gastric distress, and large doses cause vomiting, and kidney and liver damage, followed by death a few days later.

It was thought that Mozart was a victim of poisoning at the hand of rival composer, Antonio Salieri, although historians don't give this hypothesis any credence. It is far more likely that Mozart was poisoned by his doctors. A heavy drinker, Mozart was known to also overindulge in the popular hangover cure of the day that contains antimony, tartar emetic, C₄H₄KO₇Sb, which was provided by his doctors.

Stibnite

For some time, China has been the largest producer of antimony and its compounds, with most production coming from the Xikuangshan Mine in Hunan. The industrial methods to produce antimony are roasting and subsequent carbothermal reduction or direct reduction of stibnite with iron.

For more information visit:-
http://www.theguardian.com/science/grrlscientist/2012/feb/24/1?guni=Article:in%20body%20link
http://en.wikipedia.org/wiki/Antimony