#Tabletop accelerator shoots cheap antimatter bullets Make way for the antimatter gun. A tabletop device just 10 square metres in size can spit out energetic bursts of positrons as dense as those kicked out by the giant particle-factories at CERN.
Each positron-packed bullet lasts for just a fraction of a second so don't expect to fill the tank of your antimatter engine any time soon.
Instead the smaller cheaper machine might help labs around the world study deep-space objects such as powerful radiation jets squirted out by black holes.
Antiparticles have the same mass as their ordinary particle counterparts but carry an opposite charge and spin.
The particles annihilate on contact with ordinary matter vanishing in a puff of energy which makes it difficult to produce
and study them On earth. Huge machines at particle physics labs such as CERN near Geneva Switzerland have been churning out antimatter for over a decade.
But it is an expensive pursuit that for CERN requires a 190-metre-long track.
Instead Gianluca Sarri at Queen's university Belfast UK and colleagues used rapid laser bursts to make positrons in their smaller budget device.
The laser pulse ionises inert helium gas generating a stream of high-speed electrons. This electron beam is directed at a thin metallic foil
so that it crashes into metal atoms releasing a jet of electrons and positrons. These particles are separated into two beams with magnets (Physical Review Letters doi. org/m2n.
The team call their device an antimatter gun because the bursts of positrons last just 30 femtoseconds (quadrillionths of a second).
Despite their short duration the beams contain a quadrillion positrons per cubic centimetre says Sarri meaning they are comparable in density to the ones made at CERN.
In 2008 scientists at the Lawrence Livermore National Laboratory in California produced large quantities of antimatter by directing an extremely powerful laser at a tiny gold disc.
Sarri says his setup is much more practical and cheaper: They needed much stronger lasers
and those lasers are expensive. Also they produced streams of positrons that were extremely broad
whereas our jet is a hundred times narrower and remains pencil-like as it propagates he adds.
This is similar to the powerful streams of matter-antimatter observed outside pulsars and black holes. CERN physicist Niels Madsen notes though that the tabletop device has limitations.
It only makes relatively light particles like positrons whereas to make an anti-atom you also need antiprotons
which are almost 2000 times more massive. For now he says making heavier antiparticles is not doable in a small lab in a cheap fashion.
Nor does the smaller machine address the problem of antimatter storage. To hold antimatter stable it must be chilled
and the tabletop method makes searing-hot beams of particles moving at near light speed. As an alternative says Sarri the beams can be used to mimic the way particle fountains from black holes
and pulsars shoot through and interact with gases in the interstellar medium creating mini versions of these enigmatic astrophysical phenomena in the lab for the first time.
This article will appear in print under the headline Antimatter bullets get fast and chea a
#China inches closer to building its own space station Update 11 june 2013: The China National Space Administration successfully launched its Shenzhou-10 mission to low Earth orbit at 0938 GMT today.
The Long March 2f rocket lifted off flawlessly from the Jiuquan space centre in Mongolia's Gobi desert
and headed towards the fledgling spacefaring nation's space station Tiangong 1 around which it is expected to test manoeuvres before docking for a 15-day stay on orbit.
Original article published 10 june 2013china will launch the Shenzhou-10 spacecraft on 11 june lofting three astronauts on a 15-day mission to learn how to rendezvous
and dock with an orbiting module. The mission is the last of three scheduled experiments designed to help astronauts master the skills for building
If you can grow large particles they will disappear very quickly says Nienke van der Marel of Leiden Observatory in The netherlands.
It means there must be some mechanism that is keeping the large dust particles there because they're not drifting inwards.
The planet also only briefly had a magnetic field to protect its surface from cosmic radiation
and minerals that could act like batteries allowing electrons to flow and bring energy to any potential organisms.
and gained electrons and so could have acted as microbial energy sources. All these clues point to ancient Mars hosting neutral slightly salty liquid water that could have supported primitive life.
The rover's Sample Analysis at Mars instrument (SAM) also found carbon dioxide and hints of other carbon-based molecules in the drilled sample.
Unlike with previous soil samples this time the drill has dug beneath the surface layers of rock that have been altered by wind and radiation.
and friction the pulverised particles were sent up the screw-shaped drill bore and into a receptacle where they were sifted
#8th-century tree rings hint at close-range space blast A blast of radiation that hit Earth circa AD 770 may have been caused not by a solar flare but by the energetic debris from the collision of two nearby neutron stars.
Normally levels of the isotope differ by just 0. 05 per cent annually but Miyake found a 1. 2 per cent leap in those years that could only have been caused by extremely high-energy cosmic rays hitting the Earth.
and European trees from the same era while Antarctic ice cores from 775 also have increases in beryllium-10 another isotope caused by cosmic rays.
and thought to be caused by the collision of two neutron stars black holes or white dwarfs. The pair suggest that the odd isotope levels in the trees
and in the Antarctic ice are the first evidence for a burst much closer to home.
They suggest looking for a neutron star between 3000 and 12000 light years away left over from such a merger.
Such particles could help scientists to track specific molecules produced in the body monitor a tumor s environment
In a paper appearing in the Nov 18 issue of Nature Communications the researchers demonstrate the use of the particles which carry distinct sensors for fluorescence
Wherever there is a high concentration of Vitamin c the particles show a strong fluorescent signal but little MRI contrast.
Future versions of the particles could be designed to detect reactive oxygen species that often correlate with disease says Jeremiah Johnson an assistant professor of chemistry at MIT and senior author of the study.
They could also be tailored to detect more than one molecule at a time. You may be able to learn more about how diseases progress
Dual actionjohnson and his colleagues designed the particles so they can be assembled from building blocks made of polymer chains carrying either an organic MRI contrast agent called a nitroxide
or a fluorescent molecule called Cy5. 5. When mixed together in a desired ratio these building blocks join to form a specific nanosized structure the authors call a branched bottlebrush polymer.
For this study they created particles in which 99 percent of the chains carry nitroxides and 1 percent carry Cy5. 5. Nitroxides are reactive molecules that contain a nitrogen atom bound to an oxygen atom with an unpaired electron.
Nitroxides suppress Cy5. 5 s fluorescence but when the nitroxides encounter a molecule such as Vitamin c from
which they can grab electrons they become inactive and Cy5. 5 fluoresces. Nitroxides typically have a very short half-life in living systems
but University of Nebraska chemistry professor Andrzej Rajca who is also an author of the new Nature Communications paper recently discovered that their half-life can be extended by attaching two bulky structures to them.
The researchers found that their imaging particles accumulated in the liver as nanoparticles usually do.
The mouse liver produces Vitamin c so once the particles reached the liver they grabbed electrons from Vitamin c turning off the MRI signal
when the sensor encounters a target molecule such as Vitamin c. They have created also nanoparticles carrying the fluorescent agent plus up to three different drugs.
These particles could also be used to evaluate the level of oxygen radicals in a patient s tumor which can reveal valuable information about how aggressive the tumor is.
However this DNA is produced only when activated by the presence of a predetermined molecule or another type of input such as light.
and an antibiotic derivative called atc but it could be tailored to many other molecules or even signals produced by the cell Lu says.
The researchers have dubbed the system easurable virtual reality (MVR) a spin on conventional virtual reality that designed to visualize a robot erceptions and understanding of the world
You can look at our technology as a high-speed gearbox that every few nanoseconds modulates the amount of power that the power amplifier draws from the battery explains Joel Dawson Eta Devices chief technology officer
The properties of the drug molecule have to be taken into account in the design of local therapy that s effective says Cima.
There s a zone around each one of these devices where it can work depending on the molecule.
#Microscopic walkers find their way across cell surfaces Nature has developed a wide variety of methods for guiding particular cells enzymes and molecules to specific structures inside the body:
The system uses a pair of linked particles with magnetic properties. In the presence of a magnetic field the paired particles begin to tumble across a surface with first one particle
and then the other making contact in effect walking across the surface. So far the work has been carried out on a model cell surface on a functionalized microscope slide
The particles naturally migrate toward high-friction regions where they could then be induced to interact with a surface by active molecules attached to them.
The use of a pattern that localizes particles may be useful to enhance the localization of particles with specific properties.
#Nanoparticles get a magnetic handle A long-sought goal of creating particles that can emit a colorful fluorescent glow in a biological environment
And finally the particles could have a coating of a bioreactive substance that could seek out
and bind with particular molecules within the body such as markers for tumor cells or other disease agents.
For one thing he says such particles have been too large to make practical probes of living tissue: They ve tended to have wasted a lot of volume Bawendi says.
In addition previous efforts were unable to produce particles of uniform and predictable size which could also be an essential property for diagnostic or therapeutic applications.
The new method produces the combination of desired properties in as small a package as possible Bawendi says which could help pave the way for particles with other useful properties such as the ability to bind with a specific type of bioreceptor or another
molecule of interest. In the technique developed by Bawendi s team led by lead author and postdoc Ou Chen the nanoparticles crystallize such that they self-assemble in exactly the way that leads to the most useful outcome:
The magnetic particles cluster at the center while fluorescent particles form a uniform coating around them.
That puts the fluorescent molecules in the most visible location for allowing the nanoparticles to be tracked optically through a microscope.
These are beautiful structures they re so clean Bawendi says. That uniformity arises in part
Initially at least the particles might be used to probe basic biological functions within cells Bawendi suggests.
As the work continues later experiments may add additional materials to the particles coating so that they interact in specific ways with molecules or structures within the cell either for diagnosis or treatment.
Watch how supernanoparticles are made to glow and manipulated with magnets inside a cancer cell. Video: Melanie Gonick/MIT The ability to manipulate the particles with electromagnets is key to using them in biological research Bawendi explains:
The tiny particles could otherwise get lost in the jumble of molecules circulating within a cell.
Without a magnetic handle it s like a needle in a haystack he says. But with the magnetism you can find it easily.
A silica coating on the particles allows additional molecules to attach causing the particles to bind with specific structures within the cell.
Silica makes it completely flexible; it s a well developed material that can bind to almost anything Bawendi says.
For example the coating could have a molecule that binds to a specific type of tumor cells;
We often use the term artificial atoms in the community to describe how we are exploiting a new periodic table of fundamental building blocks to design materials
electrostatic forces to eject streams of ions. The technology has a range of promising applications:
array that generates 10 times the ion current per emitter that previous arrays did. Ion current is a measure of the charge carried by moving ions
which translates directly to the rate at which particles can be ejected. Higher currents thus promise more-efficient manufacturing and more-nimble satellites.
The same prototype also crams 1900 emitters onto a chip that s only a centimeter square quadrupling the array size and emitter density of even the best of its predecessors.
which droplets clumps of molecules rather than ions individual molecules begin streaming off of the emitters.
The ions ejected by Velsquez-Garc a s prototype are produced from an ionic salt that s liquid at room temperature.
and ideally ejected one molecule at a time. Slow the flowwhen the ion current in an emitter gets high enough droplet formation is inevitable.
But earlier emitter arrays those built both by Velsquez-Garc a s group and by others fell well short of that threshold.
Increasing an array s ion current is a matter of regulating the flow of the ionic salt up the emitters sides.
But in the new work they instead used carbon nanotubes atom-thick sheets of carbon rolled into cylinders grown on the slopes of the emitters like trees on a mountainside.
and height of the nanotubes the researchers were able to achieve a fluid flow that enabled an operating ion current at very near the theoretical limit.
which is broken into particles by chemical reactions with both the substrate and the environment. Then they expose the array to a plasma rich in carbon.
The nanotubes grow up under the catalyst particles which sit atop them until the catalyst degrades.
Typically the interest of this type of emitter is to be able to emit a beam of ions
Using their nanotube forest they re able to get the devices to operate in pure ion mode
The reason you d like to be in ion mode is to have the most efficient conversion of the mass of the propellant into the momentum of the spacecraft t
The more we understand about why a molecule is toxic and methods that will make these organisms more tolerant the more people will get ideas about how to attack other more severe problems of toxicity says Stephanopoulos one of the senior authors of the Science paper.
Instead the changes influenced their electrochemical membrane gradients differences in ion concentrations inside and outside the membrane
which produce energy that the cell can harness to control the flow of various molecules into and out of the cell.
which are located in the cell membrane and pump potassium in and protons out. Industrial relevancebefore yeast begin their work producing ethanol the starting material usually corn must be broken down into glucose.
These fatty molecules have shown promise as delivery vehicles for RNA interference a process that allows disease-causing genes to be turned off with small strands of RNA.#
or other large molecules to enter the brain through the bloodstream.##The research was funded by the National institutes of health the Packard Award in Science and Engineering Sanofi Pharmaceuticals Foxconn Technology Group and the Hertz Foundation e
Working with researchers at the Broad Institute the team analyzed blood samples for more than 100 different metabolites molecules such as proteins
and bacteriophage particles that bind to the bacteria and inject the genes. Both of these carriers successfully spread the CRISPR genes through the population of drug-resistant bacteria.
and deformation of the elastomer further activates special mechanically responsive molecules embedded in the elastomer,
both the elastomer and the molecules return to their relaxed state like the cephalopod skin with muscles relaxed.
what counts as infected red blood cells versus some dust particles stuck on the plate. It really takes a lot of practice he says.
Those crystals interfere with the normal magnetic spins of hydrogen atoms. When exposed to a powerful magnetic field hydrogen atoms align their spins in the same direction.
When a second smaller field perturbs the atoms they should all change their spins in synchrony
but if another magnetic particle such as hemozoin is present this synchrony is disrupted through a process called relaxation.
The more magnetic particles are present the more quickly the synchrony is disrupted. What we are trying to really measure is how the hydrogen s nuclear magnetic resonance is affected by the proximity of other magnetic particles Han says.
For this study the researchers used a 0. 5-tesla magnet much less expensive and powerful than the 2
-or 3-tesla magnets typically required for MRI diagnostic imaging which can cost up to $2 million.
Battery pileup ahead One motivation for using the lead in old car batteries is that battery technology is undergoing rapid change, with new, more efficient types, such as lithium-ion batteries,
#RNA combination therapy for lung cancer offers promise for personalized medicine Small RNA molecules including micrornas (mirnas)
treatment with cisplatin a small-molecule standard-care chemotherapy drug; treatment#with nanoparticles carrying both mir-34a and sikras;
If the probe binds to a trapped DNA molecule it means that sequence is methylated.
or designing it to carry a photosensitive molecule that forms hydrogels when exposed to light.
So you could filter how much solar radiation you want coming in and also shed raindrops. This is an opportunity for the future.
For example human nasal passages are lined with cilia small hairs that sway back and forth to remove dust and other foreign particles.
Others have designed such magnetically actuated materials by infusing polymers with magnetic particles. However Wang says it s difficult to control the distribution and therefore the movement of particles through a polymer.
MIT engineers show their magnetic microhairs in action. Video: Melanie Gonick/MIT Instead she and Zhu chose to manufacture an array of microscopic pillars that uniformly tilt in response to a magnetic field.
or particles move across them. The work might enable new kinds of biomedical or microfluidic devices or solar panels that could automatically clean themselves of dust and grit.
or other forces to move fluids or particles. Varanasi s team decided to use external fields such as magnetic fields to make surfaces active exerting precise control over the behavior of particles
or droplets moving over them. The system makes use of a microtextured surface with bumps
or ridges just a few micrometers across that is then impregnated with a fluid that can be manipulated for example an oil infused with tiny magnetic particles or ferrofluid
When droplets of water or tiny particles are placed on the surface a thin coating of the fluid covers them forming a magnetic cloak.
or particle along as the layer itself is drawn magnetically across the surface. Tiny ferromagnetic particles approximately 10 nanometers in diameter in the ferrofluid could allow precision control
when it s needed such as in a microfluidic device used to test biological or chemical samples by mixing them with a variety of reagents.
While other researchers have developed systems that use magnetism to move particles or fluids these require the material being moved to be magnetic and very strong magnetic fields to move them around.
and particles slide around with virtually no friction needs much less force to move these materials.
The researchers found that by controlling the concentration of electrons in a graphene sheet they could change the way the material responds to a short but intense light pulse.
If the graphene sheet starts out with low electron concentration the pulse increases the material s electrical conductivity.
This behavior is similar to that of traditional semiconductors such as silicon and germanium. But if the graphene starts out with high electron concentration the pulse decreases its conductivity the same way that a metal usually behaves.
Therefore by modulating graphene's electron concentration the researchers found that they could effectively alter graphene's photoconductive properties from semiconductorlike to metallike.
The finding also explains the photoresponse of graphene reported previously by different research groups which studied graphene samples with differing concentration of electrons.
We were able to tune the number of electrons in graphene and get either response,
Frenzel says. To perform this study the team deposited graphene on top of an insulating layer with a thin metallic film beneath it;
and the bottom electrode the electron concentration of graphene could be tuned. The researchers then illuminated graphene with a strong light pulse and measured the change of electrical conduction by assessing the transmission of a second low-frequency light pulse.
In a surprising finding the team discovered that part of the conductivity reduction at high electron concentration stems from a unique characteristic of graphene:
its electrons travel at a constant speed similar to photons which causes the conductivity to decrease when the electron temperature increases under the illumination of the laser pulse.
Our experiment reveals that the cause of photoconductivity in graphene is very different from that in a normal metal or semiconductors,
because it presents a systematic study of the doping dependence of the low energy dynamics which has received not much attention so far."
when electrically charged cause electrons to create photons of the same wavelength or color traveling in the same direction.
and screen hundreds of thousands of compounds to identify molecules that can powerfully and precisely influence specific biological pathways relevant to psychiatric disorders.
vaporizing the surrounding water molecules as steam. But initiating this reaction requires very intense solar energy about 1, 000 times that of an average sunny day.
and weak interaction with the rest of the environment including nonmetallic materials and humans. In fact they demonstrated that they could light the bulb at roughly 45 percent efficiency with all six researchers standing in between the two coils.
MIT engineers have developed now the first light-sensitive molecule that enables neurons to be silenced noninvasively, using a light source outside the skull.
or pumps that influence electrical activity by controlling the flow of ions in or out of cells.
these molecules, found in the bacteria Haloarcula marismortui and Haloarcula vallismortis, did not induce a strong enough photocurrent an electric current in response to light to be useful in controlling neuron activity.
Boyden says. ince these molecules come from species other than humans, many studies must be done to evaluate their safety and efficacy in the context of treatment,
It protects the body from the hazards of ultraviolet and other radiation that can damage cells and lead to skin cancer,
such that the orientations of the stacked molecules can be arbitrary and the sizes of the crystals different, forming aggregate structures that are disordered highly.
While eumelanin molecules all share a basic chemistry, more than 100 variations of that composition exist;
the slight variations from one molecule to another may contribute to the disorder that broadens the ability to absorb light,
While this analysis still leaves open questions about the precise structure of eumelanin molecules, Buehler says,
A similar combination of computational modeling based on quantum mechanics molecular dynamics, and direct observation using electron microscopy an probably be applied to many systems,
which provoke calcium ions to stream into each cell as it fires. By engineering fluorescent proteins to glow when they bind calcium,
which can then be recombined using a computer algorithm to recreate the 3-D structure. f you have one light-emitting molecule in your sample,
you can infer the three-dimensional position of where the molecule was, says Boyden, who is a member of MIT Media Lab and Mcgovern Institute for Brain Research.
which uses a helium-filled shell to float as high as a skyscraper and capture the stronger steadier winds available at that altitude.
Hepatocytes grab onto these particles because they resemble the fatty droplets that circulate in the blood after a high-fat meal is consumed. he liver is a natural destination for nanoparticles,
The new MIT particles consist of three or more concentric spheres made of short chains of a chemically modified polymer.
and released once the particles enter a target cell. Gene silencing A key feature of the MIT system is that the scientists were able to create a ibraryof many different materials
400 variants of their particles in cervical cancer cells by measuring whether they could turn off a gene coding for a fluorescent protein that had been added to the cells.
With the best-performing particles, the researchers reduced gene expression by more than 50 percent, for a dose of only 0. 20 milligrams per kilogram of solution about one-hundredth of the amount required with existing endothelial
but the particles also successfully delivered RNA to the kidneys and heart, among other organs.
Although the particles did penetrate endothelial cells in the liver, they did not enter liver hepatocytes. hat interesting is that by changing the chemistry of the nanoparticle you can affect delivery to different parts of the body,
The researchers plan to test additional potential targets in hopes that these particles could eventually be deployed to treat cancer, atherosclerosis,
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