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  • richardmitnick 1:24 pm on December 13, 2017 Permalink | Reply
    Tags: , , , , , Extragalactic jets and why they collapse, Extragalactic jets are powerful streams of particles blasted from feeding supermassive black holes, The research was conducted mathematically using 3D computer simulations to study how instabilities and turbulence develop, U Leeds, Usually at the hearts of active galaxies such as quasars and radio galaxies, Weak points in the structure of extragalactic jets may be what causes them to collapse into enormous plumes   

    From U Leeds via COSMOS: “Extragalactic jets, and why they collapse” 

    U Leeds bloc

    University of Leeds

    COSMOS

    13 December 2017
    Lauren Fuge

    Mathematics shed light on a powerful but poorly understood astronomical phenomenon.

    1
    An artist’s impression of an extragalactic jet. MARK GARLICK/SCIENCE PHOTO LIBRARY.

    Weak points in the structure of extragalactic jets may be what causes them to collapse into enormous plumes, according to researchers at the University of Leeds, UK.

    First observed in 1918 zooming out from the massive galaxy Messier 87, extragalactic jets are powerful streams of particles blasted from feeding supermassive black holes, usually at the hearts of active galaxies such as quasars and radio galaxies. They are remarkably energetic and stretch out for millions of light-years.

    Scientists still don’t know much about these powerful phenomena. Even their composition is uncertain. Two popular models suggest they are made up of either positron-electron plasma or a mix of electrons, positrons, and atomic nuclei. It is well-known, however, that although they mostly remain stable, sometimes these monstrous streamers disintegrate into huge plume-like structures.

    The study, published in Nature Astronomy, discovered that this disintegration is likely caused by unexpected weak points, causing instabilities similar to those that can develop in water flowing through a curved pipe.

    According to lead author Kostas Gourgouliatos, the weak points are created by their narrow oval shape, which gives them a curved boundary.

    “Instability starts at the curved boundary, travels upstream on the jet and then converges at one point,” explains Gourgouliatos. “Below this point the jet stays tidy and tight but everything above will be destroyed and creates a large cosmic plume.”

    The research was conducted mathematically, using 3D computer simulations to study how instabilities and turbulence develop. But the collapse can also be observed.

    “When the jet disintegrates into a plume it releases heat, making them easier to spot on telescopes,” Gourgouliatos says. “The jets and their plumes are so bright that sometimes they outshine their host galaxies and are always more easily spotted than black holes, which are inferred indirectly.”

    The formation and evolution of these highly complex phenomena are still open areas of research. It is thought that as a black hole devours gas and dust from its accretion disc, particles can be accelerated to immense speeds and form two narrow but highly energetic beams, like giant party poppers in space.

    “The observed instability exhibited some rather unexpected features,” adds co-author Serguei Komissarov. The stability seems to be related to the centrifugal force acting on the fluid elements that zoom out along curved streamlines. According to Komissarov, nobody expected such centrifugal instability to be important in jet dynamics.

    See the full article here.

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    U Leeds Campus

    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
  • richardmitnick 3:06 pm on July 18, 2017 Permalink | Reply
    Tags: , , , U Leeds   

    From COSMOS: “How giant atoms may help catch gravitational waves from the Big Bang” 

    Cosmos Magazine bloc

    COSMOS

    7.18.17
    Diego A. Quiñones, U Leeds

    Huge, highly excited atoms may give off flashes of light when hit by a gravitational wave.

    1
    Some of the earliest known galaxies in the universe, seen by the Hubble Space Telescope. NASA/ESA

    NASA/ESA Hubble Telescope

    There was a lot of excitement last year when the LIGO collaboration detected gravitational waves, which are ripples in the fabric of space itself.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    And it’s no wonder – it was one of the most important discoveries of the century. By measuring gravitational waves from intense astrophysical processes like merging black holes, the experiment opens up a completely new way of observing and understanding the universe.

    But there are limits to what LIGO can do. While gravitational waves exist with a big variety of frequencies, LIGO can only detect those within a certain range. In particular, there’s no way of measuring the type of high frequency gravitational waves that were generated in the Big Bang itself. Catching such waves would revolutionise cosmology, giving us crucial information about how the universe came to be. Our research presents a model that may one day enable this.

    In the theory of general relativity developed by Einstein, the mass of an object curves space and time – the more mass, the more curvature. This is similar to how a person stretches the fabric of a trampoline when stepping on it. If the person starts moving up and down, this would generate undulations in the fabric that will move outwards from the position of the person. The speed at which the person is jumping will determine the frequency of the generated ripples in the fabric.

    An important trace of the Big Bang is the Cosmic Microwave Background.

    CMB per ESA/Planck

    ESA/Planck

    This is the radiation left over from the birth of the universe, created about 300,000 years after the Big Bang. But the birth of our universe also created gravitational waves – and these would have originated just a fraction of a second after the event. Because these gravitational waves contain invaluable information about the origin of the universe, there is a lot of interest in detecting them. The waves with the highest frequencies may have originated during phase transitions of the primitive universe or by vibrations and snapping of cosmic strings.

    An instant flash of brightness

    Our research team, from the universities of Aberdeen and Leeds, think that atoms may have an edge in detecting elusive, high-frequency gravitational waves. We have calculated that a group of “highly excited” atoms (called Rydberg atoms – in which the electrons have been pushed out far away from the atom’s nucleus, making it huge – will emit a bright pulse of light when hit by a gravitational wave.

    To make the atoms excited, we shine a light on them. Each of these enlarged atoms is usually very fragile and the slightest perturbation will make them collapse, releasing the absorbed light. However, the interaction with a gravitational wave may be too weak, and its effect will be masked by the many interactions such as collisions with other atoms or particles.

    Rather than analysing the interaction with individual atoms, we model the collective behaviour of a big group of atoms packed together. If the group of atoms is exposed to a common field, like our oscillating gravitational field, this will induce the excited atoms to decay all at the same time. The atoms will then release a large number of photons (light particles), generating an intense pulse of light, dubbed “superradiance”.

    As Rydberg atoms subjected to a gravitational wave will superradiate as a result of the interaction, we can guess that a gravitational wave has passed through the atomic ensemble whenever we see a light pulse.

    By changing the size of the atoms, we can make them radiate to different frequencies of the gravitational wave. This can be this useful for detection in different ranges. Using the proper kind of atoms, and under ideal conditions, it could be possible to use this technique to measure relic gravitational waves from the birth of the universe. By analysing the signal of the atoms it is possible to determine the properties, and therefore the origin, of the gravitational waves.

    There may be some challenges for this experimental technique: the main one is getting the atoms in an highly excited state. Another one is to have enough atoms, as they are so big that they become very hard to contain.

    A theory of everything?

    Beyond the possibility of studying gravitational waves from the birth of the universe, the ultimate goal of the research is to detect gravitational fluctuations of empty space itself – the vacuum. These are extremely faint gravitational variations that occur spontaneously at the smallest scale, popping up out of

    Discovering such waves could lead to the unification of general relativity and quantum mechanics, one of the greatest challenges in modern physics. General relativity is unparalleled when it comes to describing the world on a large scale, such as planets and galaxies, while quantum mechanics perfectly describes physics on the smallest scale, such as the atom or even parts of the atom. But working out the gravitational impact of the tiniest of particles will therefore help bridge this divide.

    But discovering the waves associated with such quantum fluctuations would require a great number of atoms prepared with an enormous amount of energy, which may not be possible to do in the laboratory. Rather than doing this, it might be possible to use Rydberg atoms in outer space. Enormous clouds of these atoms exist around white dwarfs – stars which have run out of fuel – and inside nebulas with sizes more than four times larger than anything that can be created on Earth. Radiation coming from these sources could contain the signature of the vacuum gravitational fluctuations, waiting to be unveiled.

    See the full article here .

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  • richardmitnick 11:03 am on April 13, 2017 Permalink | Reply
    Tags: , Mud volcanoes deliver new clue to life beneath ocean floor, , U Leeds   

    From U Leeds: “Mud volcanoes deliver new clue to life beneath ocean floor” 

    U Leeds bloc

    University of Leeds

    10 April 2017

    1
    Distribution of elements in hydrated mantle rocks. Image credit: Dr Ivan Savov, University of Leeds

    Rock fragments brought to the sea floor by massive mud volcanoes have given scientists new clues about how far life may extend into the Earth’s interior.

    A team of scientists, including Dr Ivan Savov from the University of Leeds, have confirmed the presence of organic matter in rock fragments brought up to the seafloor from as deep as 10 km within the Earth’s mantle – tripling the previously estimated depth limit for life.

    The rock fragments were discovered by Dr Savov as part of a deep sea drilling expedition near the deepest place on the planet – the Challenger Deep in the Pacific Ocean.

    Study co-author Dr Savov, a geoscientist at the School of Earth and Environment, said: “The findings give us new insight into the habitability of the planet.

    “Given the difficulty of obtaining samples from the deep earth, there have not been many opportunities to explore how microbial life can be supported in the absence of photosynthesis. The mantle rocks we studied give us a link between the deep carbon cycle and the surface world.”

    Chemical analysis of the recovered mantel rock fragments reveal evidence for microbial life deep below the mud volcano.

    This is consistent with calculations conducted by the team using the currently known temperature limit for life, 122°C, and the temperatures expected under the mud volcanoes, which suggest that life could exist as deep as 10,000 metres below the sea floor.

    This is considerably deeper than other similar regions such as mid-ocean ridges, and could have provided a sheltered habitat for life, helping it to survive the more violent phases of Earth’s early history such as meteorite bombardment and mass extinctions.

    Lead author Dr Oliver Plümper, Earth scientist at Utrecht University said: “You could think of this organic matter trapped within a rock a bit like a message in a bottle.

    “The mud volcanoes are a unique window into the deep subsurface and allow us to probe processes that are otherwise hidden from us. Finding the organic material within the rock was very exciting as it may point to a deep biosphere below the mud volcanoes.”

    The massive mud volcanoes sit above the Izu-Bonin-Mariana subduction zone, where the Pacific Plate is dragged under the Philippine Sea Plate.

    Fuelled by fluids that are released as the down-going plate heats up, the mantle rocks deep below the mud volcano undergo chemical reactions with the fluids during a process called serpentinization.

    This process is affiliated with life at mid-ocean ridges and may feed microbial life that does not depend on light for its main energy source.

    The study Subduction zone forearc serpentinites as incubators for deep microbial life is published in Proceedings of the National Academy of Sciences of the United States of America (PNAS) 10 April 2017

    From Science Alert:

    11 APR 2017
    PETER DOCKRILL

    3
    Stefano Bolognini/Flickr

    Scientists may have discovered evidence of the deepest microbial life ever found on the planet, detecting the presence of organic matter in rock fragments spewed up by mud volcanoes near the deepest place on Earth, the Mariana Trench.

    3

    “This is another hint at a great, deep biosphere on our planet,” lead researcher Oliver Plümper from Utrecht University in the Netherlands told National Geographic.

    “It could be huge or very small, but there is definitely something going on that we don’t understand yet.”

    Plümper and his team ran a chemical analysis of rock fragments brought up to the seafloor by the South Chamorro Seamount, a large mud volcano underneath the western Pacific Ocean.

    While researchers are hoping to find signs of alien lifeforms lurking under the surface of Jupiter’s moon Europa and Saturn’s moon Enceladus, the discovery highlights the possibility that equally strange and unknown organisms dwell hidden on Earth, buried as far as 10 kilometres (6.2 miles) below the sea floor.

    See the full article here.

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    U Leeds Campus

    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
  • richardmitnick 9:44 pm on December 20, 2016 Permalink | Reply
    Tags: A jet stream within the Earth’s molten iron core, , , , U Leeds   

    From Leeds: “Satellites help discover a jet stream in the Earth’s core” 

    U Leeds bloc

    University of Leeds

    19 December 2016
    No writer credit
    Contact
    Anna Martinez
    Media Relations Officer
    a.martinez@leeds.ac.uk
    +44 (0)113 343 4196

    1
    No image caption. N0 image credit

    A jet stream within the Earth’s molten iron core has been discovered by scientists using the latest satellite data that helps create an ‘x-ray’ view of the planet.

    Lead researcher Dr Phil Livermore, from the University of Leeds, said: “The European Space Agency’s Swarm satellites are providing our sharpest x-ray image yet of the core.

    ESA/Swarm
    ESA/Swarm

    We’ve not only seen this jet stream clearly for the first time, but we understand why it’s there.

    “We can explain it as an accelerating band of molten iron circling the North Pole, like the jet stream in the atmosphere,” said Dr Livermore, from the School of Earth and Environment at Leeds.

    Because of the core’s remote location under 3,000 kilometres of rock, for many years scientists have studied the Earth’s core by measuring the planet’s magnetic field – one of the few options available.

    Previous research had found that changes in the magnetic field indicated that iron in the outer core was moving faster in the northern hemisphere, mostly under Alaska and Siberia.

    But new data from the Swarm satellites has revealed these changes are actually caused by a jet stream moving at more than 40 kilometres per year.

    This is three times faster than typical outer core speeds and hundreds of thousands of times faster than the speed at which the Earth’s tectonic plates move.

    The European Space Agency’s Swarm mission features a trio of satellites which simultaneously measure and untangle the different magnetic signals which stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere. They have provided the clearest information yet about the magnetic field created in the core.

    The study, published today in Nature Geoscience, found the position of the jet stream aligns with a boundary between two different regions in the core. The jet is likely to be caused by liquid in the core moving towards this boundary from both sides, which is squeezed out sideways.

    Co-author Professor Rainer Hollerbach, from the School of Mathematics at Leeds, said: “Of course, you need a force to move the liquid towards the boundary. This could be provided by buoyancy, or perhaps more likely from changes in the magnetic field within the core.”

    Rune Floberghagen, ESA’s Swarm mission manager, said: “Further surprises are likely. The magnetic field is forever changing, and this could even make the jet stream switch direction.

    “This feature is one of the first deep-Earth discoveries made possible by Swarm. With the unprecedented resolution now possible, it’s a very exciting time – we simply don’t know what we’ll discover next about our planet.”

    Co-author Dr Chris Finlay, from the Technical University of Denmark said: “We know more about the Sun than the Earth’s core. The discovery of this jet is an exciting step in learning more about our planet’s inner workings.”

    See the full article here.

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    U Leeds Campus

    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
  • richardmitnick 1:28 pm on October 29, 2015 Permalink | Reply
    Tags: , , , U Leeds   

    From Leeds: “‘One size fits all’ when it comes to unravelling how stars form” 

    U Leeds bloc

    University of Leeds

    29 October 2015
    No Writer Credit

    1

    Observations led by astronomers at the University of Leeds have shown for the first time that a massive star, 25 times the mass of the Sun, is forming in a similar way to low-mass stars.

    The discovery, made using a new state-of-the-art telescope called the Atacama Large Millimeter/submillimeter Array (ALMA), which is based in Chile, South America, is published online today by The Astrophysical Journal Letters.

    ALMA Array
    ALMA

    Lead author Dr Katharine Johnston, from the School of Physics and Astronomy at the University of Leeds, said: “Our groundbreaking observations show that not only does this still-forming massive star feed from a disk of material that surrounds it, like young Sun-like stars do, but it also mirrors low-mass star formation in the way the disk spins around the star.

    “Without a disk to channel material onto the forming star in a thin and dense layer, energetic processes, such as stellar winds from these hot stars, would halt the material before it could reach the star. It’s like when the wind stops you in your tracks on a windy day.”

    The research is one of the final pieces of the puzzle in understanding the lifetimes of the most massive and luminous stars, called O-type stars. These stars are major contributors to heavy element production in the Universe, such as iron and gold, which they eject into space in dramatic supernovae explosions at the end of their lives.

    Bit by bit, evidence for massive stars forming in a similar way to low-mass stars has been growing. However, until now, rotating disks that look exactly like the ones around low-mass stars were only seen around B-type stars, which are less than 18 times the mass of the Sun.

    Above a stellar mass of 18 solar masses, disks that looked like those around low-mass stars have been elusive. For those stars, astronomers often instead observed fluffy rotating structures that were hundreds of times bigger than low-mass disks and looked like gigantic rotating doughnuts rather than disks.

    “We started to think that real disks may not actually exist around the most massive forming stars, and that those stars might have to form in a different way,” said Dr Johnston. “Maybe the accretion into an O-type star was much more chaotic and dynamic than for the birth of our Sun.

    “But our group took ALMA observations which show exactly what we were searching for all this time. We found a disk around an O-type star, which looks very similar to the disk that we think went on to form our Sun and the rest of the Solar System, except a gigantic scaled-up version of it. The disk we have found is at least 10 times larger and 100 times more massive than the disks that we usually see around young stars.”

    The discovery was a long time coming as massive stars form much more quickly than low mass stars, making it harder to catch one in its nascent years. Massive stars are also less abundant than low-mass stars, so you need to look much further into space for one. For instance Orion, our nearest massive star formation region, is almost ten times further away than the nearest observation of a young low-mass star with a disk still around it.

    Professor Melvin Hoare, also from the University’s School of Physics and Astronomy and a co-author of the study, said: “We needed better telescopes to resolve and peer further into the envelopes of gas that surround massive stars while they are forming. We needed a revolutionary telescope like ALMA.

    “We now want to apply for more observing time with the ALMA telescope, this time with even better resolution, to see whether the disk is smooth or fragmenting into pieces that might form other stars or even planets.”

    Further information

    The research paper, A Keplerian-like disk around the forming O-type star AFGL 4176, is published by the The Astrophysical Journal Letters on 29 October 2015.

    See the full article here.

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    U Leeds Campus

    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
  • richardmitnick 9:42 am on February 13, 2015 Permalink | Reply
    Tags: , , , U Leeds,   

    From phys.org: “Scientists discover viral ‘Enigma machine'” 

    physdotorg
    phys.org

    Feb 04, 2015

    1
    A code hidden in the arrangement of the genetic information of single-stranded RNA viruses tells the virus how to pack itself within its outer shell of proteins.

    Researchers have cracked a code that governs infections by a major group of viruses including the common cold and polio.

    Until now, scientists had not noticed the code, which had been hidden in plain sight in the sequence of the ribonucleic acid (RNA) that makes up this type of viral genome.

    But a paper published in the Proceedings of the National Academy of Sciences (PNAS) Early Edition by a group from the University of Leeds and University of York unlocks its meaning and demonstrates that jamming the code can disrupt virus assembly. Stopping a virus assembling can stop it functioning and therefore prevent disease.

    Professor Peter Stockley, Professor of Biological Chemistry in the University of Leeds’ Faculty of Biological Sciences, who led the study, said: “If you think of this as molecular warfare, these are the encrypted signals that allow a virus to deploy itself effectively.”

    “Now, for this whole class of viruses, we have found the ‘Enigma machine’—the coding system that was hiding these signals from us. We have shown that not only can we read these messages but we can jam them and stop the virus’ deployment.”

    Single-stranded RNA viruses are the simplest type of virus and were probably one of the earliest to evolve. However, they are still among the most potent and damaging of infectious pathogens.

    Rhinovirus (which causes the common cold) accounts for more infections every year than all other infectious agents put together (about 1 billion cases), while emergent infections such as chikungunya and tick-borne encephalitis are from the same ancient family.

    Other single-stranded RNA viruses include the hepatitis C virus, HIV and the winter vomiting bug norovirus.

    This breakthrough was the result of three stages of research

    •In 2012, researchers at the University of Leeds published the first observations at a single-molecule level of how the core of a single-stranded RNA virus packs itself into its outer shell—a remarkable process because the core must first be correctly folded to fit into the protective viral protein coat. The viruses solve this fiendish problem in milliseconds. The next challenge for researchers was to find out how the viruses did this.
    •University of York mathematicians Dr Eric Dykeman and Professor Reidun Twarock, working with the Leeds group, then devised mathematical algorithms to crack the code governing the process and built computer-based models of the coding system.
    •In this latest study, the two groups have unlocked the code. The group used single-molecule fluorescence spectroscopy to watch the codes being used by the satellite tobacco necrosis virus, a single stranded RNA plant virus.

    Dr Roman Tuma, Reader in Biophysics at the University of Leeds, said: “We have understood for decades that the RNA carries the genetic messages that create viral proteins, but we didn’t know that, hidden within the stream of letters we use to denote the genetic information, is a second code governing virus assembly. It is like finding a secret message within an ordinary news report and then being able to crack the whole coding system behind it.

    “This paper goes further: it also demonstrates that we could design molecules to interfere with the code, making it uninterpretable and effectively stopping the virus in its tracks.”

    Professor Reidun Twarock, of the University of York’s Department of Mathematics, said: “The Enigma machine metaphor is apt. The first observations pointed to the existence of some sort of a coding system, so we set about deciphering the cryptic patterns underpinning it using novel, purpose designed computational approaches. We found multiple dispersed patterns working together in an incredibly intricate mechanism and we were eventually able to unpick those messages. We have now proved that those computer models work in real viral messages.”

    The next step will be to widen the study into animal viruses. The researchers believe that their combination of single-molecule detection capabilities and their computational models offers a novel route for drug discovery.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 5:34 am on February 13, 2015 Permalink | Reply
    Tags: , , , , , U Leeds   

    From phys.org: “Gold nanotubes launch a three-pronged attack on cancer cells” 

    physdotorg
    phys.org

    Feb 13, 2015

    1
    Pulsed near infrared light (shown in red) is shone onto a tumour (shown in white) that is encased in blood vessels. The tumour is imaged by multispectral optoacoustic tomography via the ultrasound emission (shown in blue) from the gold nanotubes. Credit: Jing Claussen (Ithera Medical, Germany)

    Scientists have shown that gold nanotubes have many applications in fighting cancer: internal nanoprobes for high-resolution imaging; drug delivery vehicles; and agents for destroying cancer cells.

    The study, published today in the journal Advanced Functional Materials, details the first successful demonstration of the biomedical use of gold nanotubes in a mouse model of human cancer.

    Study lead author Dr Sunjie Ye, who is based in both the School of Physics and Astronomy and the Leeds Institute for Biomedical and Clinical Sciences at the University of Leeds, said: “High recurrence rates of tumours after surgical removal remain a formidable challenge in cancer therapy. Chemo- or radiotherapy is often given following surgery to prevent this, but these treatments cause serious side effects.

    Gold nanotubes – that is, gold nanoparticles with tubular structures that resemble tiny drinking straws – have the potential to enhance the efficacy of these conventional treatments by integrating diagnosis and therapy in one single system.”

    The researchers say that a new technique to control the length of nanotubes underpins the research. By controlling the length, the researchers were able to produce gold nanotubes with the right dimensions to absorb a type of light called ‘near infrared’.

    The study’s corresponding author Professor Steve Evans, from the School of Physics and Astronomy at the University of Leeds, said: “Human tissue is transparent for certain frequencies of light – in the red/infrared region. This is why parts of your hand appear red when a torch is shone through it.

    “When the gold nanotubes travel through the body, if light of the right frequency is shone on them they absorb the light. This light energy is converted to heat, rather like the warmth generated by the Sun on skin. Using a pulsed laser beam, we were able to rapidly raise the temperature in the vicinity of the nanotubes so that it was high enough to destroy cancer cells.”

    In cell-based studies, by adjusting the brightness of the laser pulse, the researchers say they were able to control whether the gold nanotubes were in cancer-destruction mode, or ready to image tumours.

    In order to see the gold nanotubes in the body, the researchers used a new type of imaging technique called ‘multispectral optoacoustic tomography’ (MSOT) to detect the gold nanotubes in mice, in which gold nanotubes had been injected intravenously. It is the first biomedical application of gold nanotubes within a living organism. It was also shown that gold nanotubes were excreted from the body and therefore are unlikely to cause problems in terms of toxicity, an important consideration when developing nanoparticles for clinical use.

    Study co-author Dr James McLaughlan, from the School of Electronic & Electrical Engineering at the University of Leeds, said: “This is the first demonstration of the production, and use for imaging and cancer therapy, of gold nanotubes that strongly absorb light within the ‘optical window’ of biological tissue.

    “The nanotubes can be tumour-targeted and have a central ‘hollow’ core that can be loaded with a therapeutic payload. This combination of targeting and localised release of a therapeutic agent could, in this age of personalised medicine, be used to identify and treat cancer with minimal toxicity to patients.”

    The use of gold nanotubes in imaging and other biomedical applications is currently progressing through trial stages towards early clinical studies.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 8:45 am on December 20, 2014 Permalink | Reply
    Tags: , , U Leeds,   

    From Leeds: “Scientists observe the Earth grow a new layer under an Icelandic volcano” 

    Leeds

    University of Leeds

    15 December 2014
    No Writer Credit

    New research into an Icelandic eruption has shed light on how the Earth’s crust forms, according to a paper published today in Nature.

    1

    When the Bárðarbunga volcano, which is buried beneath Iceland’s Vatnajökull ice cap, reawakened in August 2014, scientists had a rare opportunity to monitor how the magma flowed through cracks in the rock away from the volcano.

    2

    The molten rock forms vertical sheet-like features known as dykes, which force the surrounding rock apart.

    Study co-author Professor Andy Hooper from the Centre for Observation and Modelling of Earthquakes, volcanoes and Tectonics (COMET) at the University of Leeds explained: “New crust forms where two tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is difficult to observe.

    “However, in Iceland this happens beneath dry land. The events leading to the eruption in August 2014 are the first time that such a rifting episode has occurred there and been observed with modern tools, like GPS and satellite radar.”

    Although it has a long history of eruptions, Bárðarbunga has been increasingly restless since 2005. There was a particularly dynamic period in August and September this year, when more than 22,000 earthquakes were recorded in or around the volcano in just four weeks, due to stress being released as magma forced its way through the rock.

    Using GPS and satellite measurements, the team were able to track the path of the magma for over 45km before it reached a point where it began to erupt, and continues to do so to this day. The rate of dyke propagation was variable and slowed as the magma reached natural barriers, which were overcome by the build-up of pressure, creating a new segment.

    The dyke grows in segments, breaking through from one to the next by the build up of pressure. This explains how focused upwelling of magma under central volcanoes is effectively redistributed over large distances to create new upper crust at divergent plate boundaries, the authors conclude.

    As well as the dyke, the team found ‘ice cauldrons’ – shallow depressions in the ice with circular crevasses, where the base of the glacier had been melted by magma. In addition, radar measurements showed that the ice inside Bárðarbunga’s crater had sunk by 16m, as the volcano floor collapsed.

    COMET PhD student Karsten Spaans from the University of Leeds, a co-author of the study, added: “Using radar measurements from space, we can form an image of caldera movement occurring in one day. Usually we expect to see just noise in the image, but we were amazed to see up to 55cm of subsidence.”

    Like other liquids, magma flows along the path of least resistance, which explains why the dyke at Bárðarbunga changed direction as it progressed. Magma flow was influenced mostly by the lie of the land to start with, but as it moved away from the steeper slopes, the influence of plate movements became more important.

    Summarising the findings, Professor Hooper said: “Our observations of this event showed that the magma injected into the crust took an incredibly roundabout path and proceeded in fits and starts.

    “Initially we were surprised at this complexity, but it turns out we can explain all the twists and turns with a relatively simple model, which considers just the pressure of rock and ice above, and the pull exerted by the plates moving apart.

    The paper Segmented lateral dyke growth in a rifting event at Bárðarbunga volcanic system, Iceland is published in Nature on 15 December 2014.

    The research leading to these results has received funding from the European Community’s Seventh Framework Programme under Grant Agreement No. 308377 (Project FUTUREVOLC).

    Read the paper here: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14111.html

    See the full article here.

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