The Great London [Search results for Chemistry] 

Hot vents on the seabed could have spontaneously produced the organic molecules necessary for life, according to new research by UCL chemists. The study shows how the surfaces of mineral particles inside hydrothermal vents have similar chemical properties to enzymes, the biological molecules that govern chemical reactions in living organisms. This means that vents are able to create simple carbon-based molecules, such as methanol and formic acid, out of the dissolved CO2 in the water.

The discovery, published in the journal Chemical Communications, explains how some of the key building blocks for organic chemistry were already being formed in nature before life emerged - and may have played a role in the emergence of the first life forms. It also has potential practical applications, showing how products such as plastics and fuels could be synthesised from CO2 rather than oil.

"There is a lot of speculation that hydrothermal vents could be the location where life on Earth began," says Nora de Leeuw, who heads the team. "There is a lot of CO2 dissolved in the water, which could provide the carbon that the chemistry of living organisms is based on, and there is plenty of energy, because the water is hot and turbulent. What our research proves is that these vents also have the chemical properties that encourage these molecules to recombine into molecules usually associated with living organisms."

The team combined laboratory experiments with supercomputer simulations to investigate the conditions under which the mineral particles would catalyse the conversion of CO2 into organic molecules. The experiments replicated the conditions present in deep sea vents, where hot and slightly alkaline water rich in dissolved CO2 passes over the mineral greigite (Fe3S4), located on the inside surfaces of the vents. These experiments hinted at the chemical processes that were underway. The simulations, which were run on UCL's Legion supercomputer and HECToR (the UK national supercomputing service), provided a molecule-by-molecule view of how the CO2 and greigite interacted, helping to make sense of what was being observed in the experiments. The computing power and programming expertise to accurately simulate the behaviour of individual molecules in this way has only become available in the past decade.

"We found that the surfaces and crystal structures inside these vents act as catalysts, encouraging chemical changes in the material that settles on them," says Nathan Hollingsworth, a co-author of the study. "They behave much like enzymes do in living organisms, breaking down the bonds between carbon and oxygen atoms. This lets them combine with water to produce formic acid, acetic acid, methanol and pyruvic acid. Once you have simple carbon-based chemicals such as these, it opens the door to more complex carbon-based chemistry."

Theories about the emergence of life suggest that increasingly complex carbon-based chemistry led to self-replicating molecules - and, eventually, the appearance of the first cellular life forms. This research shows how one of the first steps in this journey may have occurred. It is proof that simple organic molecules can be synthesised in nature without living organisms being present. It also confirms that hydrothermal vents are a plausible location for at least part of this process to have occurred.

The study could also have a practical applications, as it provides a method for creating carbon-based chemicals out of CO2, without the need for extreme heat or pressure. This could, in the long term, replace oil as the raw material for products such as plastics, fertilisers and fuels.

This study shows, albeit on a very small scale, that such products, which are currently produced from non-renewable raw materials, can be produced by more environmentally friendly means. If the process can be scaled up to commercially viable scales, it would not only save oil, but use up CO2 - a greenhouse gas - as a raw material.

Source: University College London [April 27, 2015]

Few Americans may be aware of it, but in 1952 a killer fog that contained pollutants covered London for five days, causing breathing problems and killing thousands of residents. The exact cause and nature of the fog has remained mostly unknown for decades, but an international team of scientists that includes several Texas A&M University-affiliated researchers believes that the mystery has been solved and that the same air chemistry also happens in China and other locales.

Texas A&M researcher Renyi Zhang, University Distinguished Professor and the Harold J. Haynes Chair of Atmospheric Sciences and Professor of Chemistry, along with graduate students Yun Lin, Wilmarie Marrero-Ortiz, Jeremiah Secrest, Yixin Li, Jiaxi Hu and Bowen Pan and researchers from China, Florida, California Israel and the UK have had their work published in the current issue of >Proceedings of the National Academy of Sciences.

In December of 1952, the fog enveloped all of London and residents at first gave it little notice because it appeared to be no different from the familiar natural fogs that have swept over Great Britain for thousands of years.

But over the next few days, conditions deteriorated, and the sky literally became dark. Visibility was reduced to only three feet in many parts of the city, all transportation was shut down and tens of thousands of people had trouble breathing. By the time the fog had lifted on Dec. 9, at least 4,000 people had died and more than 150,000 had been hospitalized. Thousands of animals in the area were also killed.

Recent British studies now say that the death count was likely far higher -- more than 12,000 people of all ages died from the killer fog. It has long been known that many of those deaths were likely caused by emissions from coal burning, but the exact chemical processes that led to the deadly mix of fog and pollution have not been fully understood over the past 60 years.

The 1952 killer fog led to the passage of the Clean Air Act in 1956 by the British Parliament and is still considered the worst air pollution event in the European history.

Through laboratory experiments and atmospheric measurements in China, the team has come up with the answers.

"People have known that sulfate was a big contributor to the fog, and sulfuric acid particles were formed from sulfur dioxide released by coal burning for residential use and power plants, and other means," Zhang says.

"But how sulfur dioxide was turned into sulfuric acid was unclear. Our results showed that this process was facilitated by nitrogen dioxide, another co-product of coal burning, and occurred initially on natural fog. Another key aspect in the conversion of sulfur dioxide to sulfate is that it produces acidic particles, which subsequently inhibits this process. Natural fog contained larger particles of several tens of micrometers in size, and the acid formed was sufficiently diluted. Evaporation of those fog particles then left smaller acidic haze particles that covered the city."

The study shows that similar chemistry occurs frequently in China, which has battled air pollution for decades. Of the 20 most polluted cities in the world, China is home to 16 of them, and Beijing often exceeds by many times the acceptable air standards set by the U.S. Environmental Protection Agency.

"The difference in China is that the haze starts from much smaller nanoparticles, and the sulfate formation process is only possible with ammonia to neutralize the particles," Zhang adds.

"In China, sulfur dioxide is mainly emitted by power plants, nitrogen dioxide is from power plants and automobiles, and ammonia comes from fertilizer use and automobiles. Again, the right chemical processes have to interplay for the deadly haze to occur in China. Interestingly, while the London fog was highly acidic, contemporary Chinese haze is basically neutral."

Zhang says China has been working diligently over the past decade to lessen its air pollution problems, but persistent poor air quality often requires people to wear breathing masks during much of the day. China's explosive industrial and manufacturing growth and urbanization over the past 25 years have contributed to the problem. "A better understanding of the air chemistry holds the key for development of effective regulatory actions in China," he adds.

"The government has pledged to do all it can to reduce emissions going forward, but it will take time," he notes. "We think we have helped solve the 1952 London fog mystery and also have given China some ideas of how to improve its air quality. Reduction in emissions for nitrogen oxides and ammonia is likely effective in disrupting this sulfate formation process."

Source: Texas A&M University [November 15, 2016]

Using the oldest fossil micrometeorites -- space dust -- ever found, Monash University-led research has made a surprising discovery about the chemistry of Earth's atmosphere 2.7 billion years ago.

The findings of a new study >published in the journal Nature -- led by Dr Andrew Tomkins and a team from the School of Earth, Atmosphere and Environment at Monash, along with scientists from the Australian Synchrotron and Imperial College, London -- challenge the accepted view that Earth's ancient atmosphere was oxygen-poor. The findings indicate instead that the ancient Earth's upper atmosphere contained about the same amount of oxygen as today, and that a methane haze layer separated this oxygen-rich upper layer from the oxygen-starved lower atmosphere.

Dr Tomkins explained how the team extracted micrometeorites from samples of ancient limestone collected in the Pilbara region in Western Australia and examined them at the Monash Centre for Electron Microscopy (MCEM) and the Australian Synchrotron.

"Using cutting-edge microscopes we found that most of the micrometeorites had once been particles of metallic iron -- common in meteorites -- that had been turned into iron oxide minerals in the upper atmosphere, indicating higher concentrations of oxygen than expected," Dr Tomkins said.

"This was an exciting result because it is the first time anyone has found a way to sample the chemistry of the ancient Earth's upper atmosphere," Dr Tomkins said.

Imperial College researcher Dr Matthew Genge -- an expert in modern cosmic dust -- performed calculations that showed oxygen concentrations in the upper atmosphere would need to be close to modern day levels to explain the observations.

"This was a surprise because it has been firmly established that the Earth's lower atmosphere was very poor in oxygen 2.7 billion years ago; how the upper atmosphere could contain so much oxygen before the appearance of photosynthetic organisms was a real puzzle," Dr Genge said.

Dr Tomkins explained that the new results suggest the Earth at this time may have had a layered atmosphere with little vertical mixing, and higher levels of oxygen in the upper atmosphere produced by the breakdown of CO 2 by ultraviolet light.

"A possible explanation for this layered atmosphere might have involved a methane haze layer at middle levels of the atmosphere. The methane in such a layer would absorb UV light, releasing heat and creating a warm zone in the atmosphere that would inhibit vertical mixing," Dr Tomkins said.

"It is incredible to think that by studying fossilised particles of space dust the width of a human hair, we can gain new insights into the chemical makeup of Earth's upper atmosphere, billions of years ago." Dr Tomkins said.

Dr Tomkins outlined next steps in the research.

"The next stage of our research will be to extract micrometeorites from a series of rocks covering over a billion years of Earth's history in order to learn more about changes in atmospheric chemistry and structure across geological time. We will focus particularly on the great oxidation event, which happened 2.4 billion years ago when there was a sudden jump in oxygen concentration in the lower atmosphere."

Source: Monash University [May 12, 2016]

Scientists have discovered that stunted growth can be a genetic response to ocean acidification, enabling some sea creatures to survive high carbon dioxide levels, both in the future and during past mass extinctions.

Using natural CO2 seeps as test sites, the international team of marine scientists and palaeontologists have studied the way in which sea snails cope in more acidic conditions ‒ simulating the change in seawater chemistry that will occur in future as more atmospheric CO2 is absorbed by the ocean.

The researchers say their findings, published in Nature Climate Change, provide an explanation as to why marine species that survived previous mass extinction events were much smaller – a phenomenon known as the ‘Lilliput effect’.

The research was funded by the EU MedSeA project and the UK Ocean Acidification Research Programme, and involved researchers from 10 institutions including Plymouth University, the University of Southampton, the Natural History Museum, London, and colleagues in Italy, Monaco, Norway and New Caledonia.

Its results provide a stark warning about the impact that continuing ocean acidification could have on marine ecosystems unless we drastically slow the rate of carbon dioxide emissions.

Dr Vittorio Garilli, at Paleosofia-APEMA, Palermo, said: “Two species of snails growing at shallow water CO2 seeps were smaller than those found in normal pH conditions, and adapted their metabolic rates to cope with the acidified seawater. These physiological changes allowed the animals to maintain calcification and to partially repair shell dissolution.”

Professor Jason Hall-Spencer, of the School of Marine Science and Engineering at Plymouth University, said: “Organisms that have been exposed to elevated CO2 levels over multiple generations provide valuable insights both into changes we can expect in marine ecosystems as CO2 emissions continue to rise unchecked, and into past mass extinctions."

“Not only do they demonstrate a similar magnitude and direction of body size change as fossil organisms, but they also reveal the physiological advantages of dwarfing,” added Professor Marco Milazzo at Palermo University.

Measurements showed that the shells from high CO2 seawater were about a third smaller than those in “normal” environments. Some of the snails were taken to the Marine Environmental Studies Laboratory at the International Atomic Energy Agency in Monaco, where their calcification rates were measured in aquaria.

Study co-leader Dr Riccardo Rodolfo-Metalpa, from the Institut de Recherche pour le Développement, said: “They developed a surprising ability to calcify and cope with shell dissolution at pH values which were thought too low for calcification to occur.”

The results – published in the paper Physiological advantages of dwarfing in surviving extinctions in high CO2 oceans – confirmed the theory that the snails had adapted to the conditions over many generations.

Professor Richard Twitchett, of the Department of Earth Sciences at the Natural History Museum, said: “The fossil record shows us that mass extinctions and dwarfing of marine shelled species are repeatedly associated with episodes of past global warming. It is likely that similar changes will increasingly affect modern marine ecosystems, especially as the current rate of ocean acidification and warming is so rapid."

Professor Hall-Spencer added: “It is critical that we understand the mechanisms by which certain species survive chronic exposure to elevated CO2 since emissions of this gas are already having adverse effects on marine foodwebs and putting food security at risk.”

Author: Andrew Merrington | Source: University of Plymouth [April 21, 2015]

Scientists analysing samples from Mars' surface have so far not conclusively detected organic compounds that are indigenous to Mars, which would be indicators of past or present life. The inconclusive results mean that researchers are now suggesting that a good place to find these organic compounds would be deep underground – from rocks that have been blasted to the surface by meteor impacts. This is because such rocks have been sheltered from the Sun's harmful radiation and from chemical processes on the surface that would degrade organic remains.

Now, a team of scientists from Imperial College London and the University of Edinburgh has replicated meteorite blasts in the lab. The aim of the study was to see if organic compounds encased in rock could survive the extreme conditions associated with them being blasted to the surface of Mars by meteorites.  The study, >published in Scientific Reports, suggests that rocks excavated through meteorite impacts may incorrectly suggest a lifeless early Mars, even if indicators of life were originally present.

In the study the team replicated blast impacts of meteorites of around 10 metres in size. The researchers found that the types of organic compounds found in microbial and algal life - long chain hydrocarbon-dominated matter- were destroyed by the pressures of impact. However, the types of organic compounds found in plant matter – dominated by aromatic hydrocarbons - underwent some chemical changes, but remained relatively resistant to impact pressures. Meteorites often contain organic matter not created by life, which have some similarities in their organic chemistry to land plants. The team infer that they also should also be resistant to blast impacts.

Their study could help future missions to Mars determine the best locations and types of blast excavated rocks to examine to find signs of life. For example, it may be that meteorite impacts of a certain size may not destroy organic compounds or scientists may need to concentrate on rocks excavated from a certain depth.

Professor Mark Sephton, co-author of the research from the Department of Earth Science and Engineering at Imperial College London, said: "We've literally only scratched the surface of Mars in our search for life, but so far the results have been inconclusive. Rocks excavated through meteorite impacts provide scientists with another unique opportunity to explore for signs of life, without having to resort to complicated drilling missions. Our study is showing us is that we may need to be nuanced in our approach to the rocks we choose to analyse."

Dr Wren Montgomery, co-author of the study from the Department of Earth Science and Engineering, added: "The study is helping us to see that when organic matter is observed on Mars, no matter where, it must be considered whether the sample could have been affected by the pressures associated with blast impacts. We still need to do more work to understand what factors may play an important role in protecting organic compounds from these blast impacts. However, we think some of the factors may include the depths at which the rock records are buried and the angles at which meteorites hit the Martian surface."

Previous in situ analyses of the Martian terrain have found inconclusive evidence for the existence organic compounds – so far only finding chlorinated organic matter. The issue for scientists has been that it is not easy to look at simple chlorine-containing organic molecules and determine the origin of the organic compound components.

NASA's Viking landers in 1976 detected chlorine-containing organic compounds, but they were thought to be chemical left-overs from cleaning procedures of Viking's equipment before it left Earth. Later, the Phoenix Mission in 2008 discovered chlorine-containing minerals on the Martian surface, but no organic compounds. In 2012 the Mars Science Laboratory Mission detected chlorinated organic matter, but they thought that the analysis process, which involved heating chlorine containing minerals and carbonaceous material together, was producing chlorine-containing organic compounds. Working out whether the source of the carbon found on Mars was carried once again from Earth or was indigenous to Mars remains frustratingly difficult for scientists.

The team carried out their research by subjecting the different types of organic matter to extreme pressure and temperature in a piston cylinder device. They then did a chemical analysis using pyrolysis-gas chromatography mass spectrometry.

The next steps will see the team investigating a broader range of pressures and temperatures, which would help them understand the likely effects of a greater range of meteorite impacts. This would enable them to identify the specific conditions under which organic material may escape the destructive effects of blasts – even when excavated from deep underground by violent events. This could help future Mars missions further refine the types and locations of rocks that they can analyse for signs of past or present life.

Author: Colin Smith | Source: Imperial College London [August 08, 2016]

The build-up and subsequent release of warm, stagnant water from the deep Arctic Ocean and Nordic Seas played a role in ending the last Ice Age within the Arctic region, according to new research led by a UCL scientist.

The study, published today in Science, examined how the circulation of the ocean north of Iceland -- the combined Arctic Ocean and Nordic Seas, called the Arctic Mediterranean -- changed since the end of the last Ice Age (~20,000-30,000 years ago).

Today, the ocean is cooled by the atmosphere during winter, producing large volumes of dense water that sink and flush through the deep Arctic Mediterranean. However, in contrast to the vigorous circulation of today, the research found that during the last Ice Age, the deep Arctic Mediterranean became like a giant stagnant pond, with deep waters not being replenished for up to 10,000 years.

This is thought to have been caused by the thick and extensive layer of sea ice and fresh water that covered much of the Arctic Mediterranean during the Ice Age, preventing the atmosphere from cooling and densifying the underlying ocean.

Dr David Thornalley (UCL Geography) said: "As well as being stagnant, these deep waters were also warm. Sitting around at the bottom of the ocean, they slowly accumulated geothermal heat from the seafloor, until a critical point was reached when the ocean became unstable.

"Suddenly, the heat previously stored in the deep Arctic Mediterranean was released to the upper ocean. The timing of this event coincides with the occurrence of evidence for a massive release of meltwater into the Nordic Seas. We hypothesize that this input of melt water was caused by the release of deep ocean heat, which melted icebergs, sea-ice and surrounding marine-terminating ice sheets."

This study highlights the important impact that changes in ocean circulation can have on climate, due to the ocean's capacity to redistribute vast quantities of heat around the globe. For example, scientists are currently concerned that ongoing changes in ocean circulation may result in warmer subsurface water that will cause enhanced melting and retreat of certain ice sheets in Greenland and Antarctica.

Dr Thornalley added: "To help predict the role of the ocean in future climate change, it is useful to investigate how ocean circulation changed in the past and what the associated climate effects were."

In this study, researchers from UCL, Woods Hole Oceanographic Institute and other partner institutions analysed the composition of calcite shells of small single-celled organisms (called foraminifera) that are found in ocean floor sediment. The shells of these organisms record the chemistry of the deep ocean at the time they were living, enabling the researchers to reconstruct past changes in ocean circulation.

By measuring the radiocarbon content of these shells, the research team was able to determine how rapidly deep water was being formed in the Arctic Mediterranean. A number of different techniques were then used to constrain past temperature changes, including measuring the ratio of magnesium and calcium, and the arrangement of isotopes of carbon and oxygen within the calcite shells of the foraminifera, both of which vary according to the temperature of the water in which the foraminifera grew.

A warmer, deep Arctic Mediterranean during glacial times has been suggested in previous studies, too. As summarised by co-author Dr Henning Bauch (GEOMAR/Germany) "It is good to see that new, independent proxy data would give strong support now to these former hypotheses."

Source: University College London [August 13, 2015]

Various specimens of Africa’s earliest coelacanth have been found in a 360 million year-old fossil estuary near Grahamstown, in South Africa’s Eastern Cape.

More than 30 complete specimens of the new fossil species, Serenichthys kowiensis, were collected from the famous Late Devonian aged Waterloo Farm locality, by palaeontologist Dr Robert Gess and described by him in collaboration with Professor Michael Coates of the University of Chicago.

Gess did the research whilst he was completing his PhD at the Evolutionary Studies Institute at the University of the Witwatersrand. An article describing the new species will be published in the in the prestigious Zoological Journal of the Linnean Society of London on Monday, 21 August.

“Remarkably, all of the delicate whole fish impressions represent juveniles. This suggests that Serenichthys was using a shallow, waterweed-filled embayment of the estuary as a nursery, as many fish do today,” says Gess.

The fossils come from black shales originally disturbed by road works at Waterloo Farm. These shales are the petrified compacted remains of mud, which was deposited in the quiet reaches of an estuary not unlike some of those along the Eastern Cape coast today.

“This earliest known record of a coelacanth nursery foreshadows a much younger counterpart, known from the 300 million year old Mazon Creek beds of Illinois in the United States,” says Gess.

“This glimpse into the early life history of ancient coelacanths raises further questions about the life history of the modern coelacanth, Latimeria, which is known to bear live young, but whether they, too, are clustered in nurseries remains unknown,” explains Coates.

360 million years ago, Africa was part of the southern supercontinent Gondwana, made up of Africa, India, Australia, Antarctica and South America. At that time, the rocks of Waterloo Farm were forming along the shores of the semi-enclosed Agulhas Sea, not far from the South Pole.

Gess originally identified coelacanth remains from the locality whilst carrying out excavations at Waterloo Farm in the mid-1990s under the supervision of Dr Norton Hiller, of the Rhodes University Geology Department. These fossils were not, however, well enough preserved to be reconstructed and described. His painstaking excavation of tons of shale salvaged during subsequent roadworks has now shed light on dozens more specimens, a few of which are preserved in exquisite detail.

These were prepared under a microscope and have allowed the species to be reconstructed in minute detail. They prove to be a new genus and species.

Coelacanths are believed to have arisen during the Devonian Period (about 419.2 ± 3.2 million years ago), however only five species of reconstructable Devonian coelacanths have previously been described, in addition to a number of very fragmentary remains. None of these came from Africa, but rather from North America, Europe, China and Australia. The new species gives important additional information on the early evolution of coelacanths.

“According to our evolutionary analysis (conducted by Gess and Coates), it is the Devonian species that most closely resembles the line leading to modern coelacanths,” says Gess.

The new species was discovered a mere 100km from the mouth of the Chalumna River, off which the type specimen of Latimeria chalumnae (the first discovered modern coelacanth) was caught in 1938.

Furthermore, the Geology Department at Rhodes, where Gess was based when he found his first fossil coelacanth, is on the site of the former Chemistry Department where Latimeria was first described. In keeping with the naming of its living relative (after an Eastern Cape river), the species name of the new fossil form, kowiensis, is after the Kowie River which rises among the hills where it was found, and the genus name, Serenichthys, honours Serena Gess, who provided land for the storage of more than 70 tons of black shale rescued from roadworks for ongoing research – in which all the new material was found.

All specimens have been deposited in the palaeontological collection of the Albany Natural History Museum, in Grahamstown, Eastern Cape Province, South Africa.

Source: University of the Witwatersrand [September 21, 2015]

Marine turtles experienced an evolutionary windfall thanks to a mass extinction of crocodyliforms around 145 million years ago, say researchers.

Crocodyliforms comprise modern crocodiles and alligators and their ancient ancestors, which were major predators that thrived on Earth millions of years ago. They evolved into a variety of species including smaller ones that lived on land through to mega-sized sea-swimming species that were up to 12 metres long. However, around 145 million years ago crocodyliforms, along with many other species, experienced a severe decline - an extinction event during a period between two epochs known as the Jurassic/Cretaceous boundary.

Now a PhD student and his colleagues from Imperial College London and University College London have carried out an extensive analysis of 200 species of crocodyliforms from a fossil database. One of the findings of the study is that the timing of the extinction coincided with the origin of modern marine turtles. The team suggest that the ecological pressure may have been lifted from early marine turtle ancestors due to the extinction of many marine crocodyliforms, which were one of their primary predators.

Jon Tennant, lead author of the study from the Department of Earth Science and Engineering at Imperial, said: "This major extinction of crocodyliforms was literally a case of out with the old and in with the new for many species. Marine turtles, the gentle, graceful creatures of the sea, may have been one of the major winners from this changing of the old guard. They began to thrive in oceans around the world when their ferocious arch-predators went into terminal decline."

In the study, published in the journal Proceedings of the Royal Society B, the researchers point to evidence in the records of a dramatic extinction of crocodyliforms during the Jurassic/Cretaceous boundary. Up to 80 per cent of species on land and in marine environments were wiped out. This decline was primarily due to a drop in sea levels, which led to a closing off of shallow marine environments such as lagoons and coastal swamps. These were the homes and primary hunting grounds for many crocodyliforms.

The decimation of many marine crocodyliforms may also have laid the way for their ecological replacement by other large predatory groups such as modern shark species and new types of plesiosaurs. Plesiosaurs were long-necked, fat-bodied and small-headed ocean-going creatures with fins, which later went extinct around 66 million years ago.

Other factors that contributed to the decline of marine crocodyliforms included a change in the chemistry of ocean water with increased sulphur toxicity and a depletion of oxygen.

While primitive crocodyliform species on land also suffered major declines, the remaining species diversified into new groups such as the now extinct notosuchians, which were much smaller in size at around 1.5 metres in length. Eusuchians also came to prominence after the extinction, which led to today's crocodiles.

To carry out the study on crocodyliforms the team used the Paleobiology Database, which is a professionally curated digital archive of all known fossil records. The team analysed almost 1,200 crocodyliform fossil records.

Scientists have known since the early 1970s about the Jurassic/Cretaceous boundary extinction from fossil records. However, researchers have focussed on other extinction events and as a consequence less has been done to understand in detail the effects of Jurassic/Cretaceous boundary extinction on species like crocodyliforms.

The next steps will see the analysis extended to other groups including dinosaurs, amphibians and mammals to learn more about the effects of the Jurassic/Cretaceous boundary on their biodiversity

Source: Imperial College London [March 09, 2016]

A new study presents evidence that the rise of atmospheric oxygenation did indeed occur 2.4-2.1 billion years ago. It also shows that biological usage of copper became prominent after the so called 'Great Oxidation Event.' An international team of researchers has recently published the study in the Proceedings of the National Academy of Sciences.

"Our findings make it possible to reconstruct nutrient content in early marine settings and demonstrate that the iron-rich content of the early oceans must have severely restricted the availability of nutrients important for life", says Dr Ernest Chi Fru of Stockholm University, who has led the research group.

The study suggests a gradual shift in mainly negative copper isotopic composition of marine carbon-rich sediments, beginning at 2.4 billion years ago (Ga), to permanently positive values after 2.3 Ga. The authors argue that the change reflects the drawn-out nature of the Great Oxidation Event (GOE), when atmospheric oxygen content went from virtually nothing, starting at 2.4 Ga, to peak at near present day levels by 2.3 Ga.

Fundamentally, the high iron content of the early oceans are suggested to have played a critical role in determining trace metal availability, whereby copper levels increased when decreasing marine iron content fell by about 1 000 times after the GOE. The research has been made by examining carbon-rich rocks deposited at the bottom of ancient oceans 2.66-2.1 billion years ago.

"The appearance of oxygen in the atmosphere is one of the most important changes in Earth's geological history that enabled the evolution of oxygen based life. Understanding the chemistry of the very early oceans and how nutrients were made available, guide our steps towards understanding the processes that govern our own evolution", says Dr Ernest Chi Fru of Stockholm University.

The study provides a tool for tracking how oxygen levels have fluctuated through Earth's history and the evolutionary changes that accompanied these fluctuations.

"Our study is highlighting how the isotopic ratios of copper can unlock the evolution of Earth's early oceans from being oxygen-poor to more like they are today. We now hope to apply this technique to understanding other major geological events in the Earth's history", says Professor Dominik Weiss, co-author from Imperial College London.

Source: Stockholm University [April 18, 2016]

Dazzling treasures combining gold and precious pigments - some of the finest illuminated manuscripts in the world - will go on display on Saturday 30 July in celebration of the Fitzwilliam Museum’s bicentenary.

The majority of the exhibits are from the Museum’s own rich collections, and those from the founding bequest of Viscount Fitzwilliam in 1816 can never leave the building and can only be seen at the Museum. For the first time, the secrets of master illuminators and the sketches hidden beneath the paintings will be revealed in a major exhibition presenting new art historical and scientific research.

Spanning the 8th to the 17th centuries, the 150 manuscripts and fragments in >COLOUR: The Art and Science of Illuminated Manuscripts guide us on a journey through time, stopping at leading artistic centres of medieval and Renaissance Europe. Exhibits highlight the incredible diversity of the Fitzwilliam’s collection: including local treasures, such as the Macclesfield Psalter made in East Anglia c.1330-1340, a leaf with a self-portrait made by the Oxford illuminator William de Brailes c.1230-1250, and a medieval encyclopaedia made in Paris c.1414 for the Duke of Savoy.

Four years of cutting-edge scientific analysis and discoveries made at the Fitzwilliam have traced the creative process from the illuminators’ original ideas through their choice of pigments and painting techniques to the completed masterpieces.

“Leading artists of the Middle Ages and early Renaissance did not think of art and science as opposing disciplines,” says curator, Dr Stella Panayotova, Keeper of Manuscripts and Printed Books. “Instead, drawing on diverse sources of knowledge, they conducted experiments with materials and techniques to create beautiful works that still fascinate us today.”

Merging art and science, COLOUR shares the research of MINIARE (Manuscript Illumination: Non-Invasive Analysis, Research and Expertise), an innovative project based at the Fitzwilliam. Collaborating with scholars from the University of Cambridge and international experts, the Museum’s curators, scientists and conservators have employed pioneering analytical techniques to identify the materials and methods used by illuminators.

“This has been an exciting project,” says research scientist, Dr Paola Ricciardi. “By combining imaging and spectroscopic analysis — methods more commonly associated with remote sensing and analytical chemistry — and by exploring such a diverse range of manuscripts, we can begin to understand how illuminators actually worked.”

“A popular misconception is that all manuscripts were made by monks and contained religious texts, but from the 11th century onwards professional scribes and artists were increasingly involved in a thriving book trade, producing both religious and secular texts. Scientific examination has revealed that illuminators sometimes made use of materials associated with other media, such as egg yolk, which was traditionally used as a binder by panel painters.”

Other discoveries include pigments rarely associated with manuscript illumination – such as the first ever example of smalt detected in a Venetian manuscript. Smalt, obtained by grinding blue glass, was found in a Venetian illumination book made c.1420. Evidently, the artist who painted it had close links with the famed glassmakers of Murano. This example predates by half a century the documented use of smalt in Venetian easel paintings.

Analyses of sketches lying beneath the paint surfaces, and of later additions and changes to paintings help to shed light on manuscripts and their owners. One French prayer book, made c.1430, was adapted over three generations to reflect the personal circumstances and dynastic anxieties of a succession of aristocratic women.

Adam and Eve were originally shown naked in an ABC commissioned c.1505 by the French Queen, Anne of Brittany (1476-1514) for her five-year-old daughter. However, a later owner, offended by the nudity, gave Eve a veil and Adam a skirt. Infrared imaging techniques and mathematical modelling have made it possible to reconstruct the original composition without harming the manuscript.

The Museum’s treasures will be displayed alongside carefully selected loans — celebrated manuscripts from Cambridge libraries as well as other institutions in the UK and overseas. These include an 8th century Gospel Book from Corpus Christi College, the University Library’s famous Life of Edward the Confessor, magnificent Apocalypses from Trinity College and Lambeth Palace, London, and a unique model book from Göttingen University.

Visitors will be encouraged to make their own discoveries in the exhibition galleries and online through a new, free digital resource: >ILLUMINATED: Manuscripts in the Making. With hundreds of high resolution digital images and infrared photographs, this interactive, cross-disciplinary resource offers users in-depth information on the manuscripts’ contents, patrons, cultural and historical contexts, as well as scientific data relating to artists’ techniques and materials.

With over 300 illustrations in full colour, the authoritative exhibition catalogue encompasses subjects as diverse as the trade in pigments, painting techniques, the medieval science of optics and modern-day forgeries. Catalogue entries and essays by leading experts offer readers insight into all aspects of colour from the practical application of pigments to its symbolic meaning.

“We are delighted to be presenting this exhibition in our bicentenary year,” says director, Tim Knox. “Ten years ago The Cambridge Illuminations was the Museum’s first ever record breaking exhibition, attracting over 80,000 visitors. People were enchanted by the remarkable beauty and delicacy of the manuscripts. I am convinced that our bicentenary visitors will again be equally inspired by the superb illuminations collected and treasured at the Fitzwilliam for 200 years, and will value this rare opportunity to find out how they were made and how we are preserving them for the future.”

COLOUR: The Art and Science of Illuminated Manuscripts will run during the second half of the Fitzwilliam’s bicentenary year, from 30 July to 30 December 2016. Admission is free.

Source: The Fitzwilliam Museum [August 01, 2016]

Astronomers using ESO telescopes and other facilities have found clear evidence of a planet orbiting the closest star to Earth, Proxima Centauri. The long-sought world, designated Proxima b, orbits its cool red parent star every 11 days and has a temperature suitable for liquid water to exist on its surface. This rocky world is a little more massive than the Earth and is the closest exoplanet to us -- and it may also be the closest possible abode for life outside the Solar System. A paper describing this milestone finding will be published in the journal Nature on 25 August 2016.

Just over four light-years from the Solar System lies a red dwarf star that has been named Proxima Centauri as it is the closest star to Earth apart from the Sun. This cool star in the constellation of Centaurus is too faint to be seen with the unaided eye and lies near to the much brighter pair of stars known as Alpha Centauri AB.

During the first half of 2016 Proxima Centauri was regularly observed with the HARPS spectrograph on the ESO 3.6-metre telescope at La Silla in Chile and simultaneously monitored by other telescopes around the world >[1]. This was the Pale Red Dot campaign, in which a team of astronomers led by Guillem Anglada-Escudé, from Queen Mary University of London, was looking for the tiny back and forth wobble of the star that would be caused by the gravitational pull of a possible orbiting planet >[2].

As this was a topic with very wide public interest, the progress of the campaign between mid-January and April 2016 was shared publicly as it happened on the Pale Red Dot website and via social media. The reports were accompanied by numerous outreach articles written by specialists around the world.

Guillem Anglada-Escudé explains the background to this unique search: "The first hints of a possible planet were spotted back in 2013, but the detection was not convincing. Since then we have worked hard to get further observations off the ground with help from ESO and others. The recent Pale Red Dot campaign has been about two years in the planning."

The Pale Red Dot data, when combined with earlier observations made at ESO observatories and elsewhere, revealed the clear signal of a truly exciting result. At times Proxima Centauri is approaching Earth at about 5 kilometres per hour -- normal human walking pace -- and at times receding at the same speed. This regular pattern of changing radial velocities repeats with a period of 11.2 days. Careful analysis of the resulting tiny Doppler shifts showed that they indicated the presence of a planet with a mass at least 1.3 times that of the Earth, orbiting about 7 million kilometres from Proxima Centauri -- only 5% of the Earth-Sun distance >[3].

Guillem Anglada-Escudé comments on the excitement of the last few months: "I kept checking the consistency of the signal every single day during the 60 nights of the Pale Red Dot campaign. The first 10 were promising, the first 20 were consistent with expectations, and at 30 days the result was pretty much definitive, so we started drafting the paper!"

Red dwarfs like Proxima Centauri are active stars and can vary in ways that would mimic the presence of a planet. To exclude this possibility the team also monitored the changing brightness of the star very carefully during the campaign using the ASH2 telescope at the San Pedro de Atacama Celestial Explorations Observatory in Chile and the Las Cumbres Observatory telescope network. Radial velocity data taken when the star was flaring were excluded from the final analysis.

Although Proxima b orbits much closer to its star than Mercury does to the Sun in the Solar System, the star itself is far fainter than the Sun. As a result Proxima b lies well within the habitable zone around the star and has an estimated surface temperature that would allow the presence of liquid water. Despite the temperate orbit of Proxima b, the conditions on the surface may be strongly affected by the ultraviolet and X-ray flares from the star -- far more intense than the Earth experiences from the Sun >[4].

Two separate papers discuss the habitability of Proxima b and its climate. They find that the existence of liquid water on the planet today cannot be ruled out and, in such case, it may be present over the surface of the planet only in the sunniest regions, either in an area in the hemisphere of the planet facing the star (synchronous rotation) or in a tropical belt (3:2 resonance rotation). Proxima b's rotation, the strong radiation from its star and the formation history of the planet makes its climate quite different from that of the Earth, and it is unlikely that Proxima b has seasons.

This discovery will be the beginning of extensive further observations, both with current instruments >[5] and with the next generation of giant telescopes such as the European Extremely Large Telescope (E-ELT). Proxima b will be a prime target for the hunt for evidence of life elsewhere in the Universe. Indeed, the Alpha Centauri system is also the target of humankind's first attempt to travel to another star system, the StarShot project.

Guillem Anglada-Escudé concludes: "Many exoplanets have been found and many more will be found, but searching for the closest potential Earth-analogue and succeeding has been the experience of a lifetime for all of us. Many people's stories and efforts have converged on this discovery. The result is also a tribute to all of them. The search for life on Proxima b comes next..."

>Notes

>[1] Besides data from the recent Pale Red Dot campaign, the paper incorporates contributions from scientists who have been observing Proxima Centauri for many years. These include members of the original UVES/ESO M-dwarf programme (Martin Kürster and Michael Endl), and exoplanet search pioneers such as R. Paul Butler. Public observations from the HARPS/Geneva team obtained over many years were also included.

>[2] The name Pale Red Dot reflects Carl Sagan's famous reference to the Earth as a pale blue dot. As Proxima Centauri is a red dwarf star it will bathe its orbiting planet in a pale red glow.

>[3] The detection reported today has been technically possible for the last 10 years. In fact, signals with smaller amplitudes have been detected previously. However, stars are not smooth balls of gas and Proxima Centauri is an active star. The robust detection of Proxima b has only been possible after reaching a detailed understanding of how the star changes on timescales from minutes to a decade, and monitoring its brightness with photometric telescopes.

>[4] The actual suitability of this kind of planet to support water and Earth-like life is a matter of intense but mostly theoretical debate. Major concerns that count against the presence of life are related to the closeness of the star. For example gravitational forces probably lock the same side of the planet in perpetual daylight, while the other side is in perpetual night. The planet's atmosphere might also slowly be evaporating or have more complex chemistry than Earth's due to stronger ultraviolet and X-ray radiation, especially during the first billion years of the star's life. However, none of the arguments has been proven conclusively and they are unlikely to be settled without direct observational evidence and characterisation of the planet's atmosphere. Similar factors apply to the planets recently found around TRAPPIST-1.

>[5] Some methods to study a planet's atmosphere depend on it passing in front of its star and the starlight passing through the atmosphere on its way to Earth. Currently there is no evidence that Proxima b transits across the disc of its parent star, and the chances of this happening seem small, but further observations to check this possibility are in progress.

This research is >published in the journal Nature.

Source: European Southern Observatory (ESO) [August 25, 2016]