To create their technology the researchers took a unique approach to detecting molecules. anoelectronic sensors typically depend on detecting charge transfer between the sensor
and a molecule in air or in solutionkulkarni says. However these previous techniques typically led to strong bonds between the molecules being detected and the sensor itself.
That binding leads to slow detection rates. nstead of detecting molecular charge we use a technique called heterodyne mixing in
which we look at the interaction between the dipoles associated with these molecules and the nanosensor at high frequencieskulkarni says.
The sensor can detect molecules in sample sizes at a ratio of several parts per billion.
To find out if stripping the lipids from cells also removes other potential molecules of interest#such as proteins DNA
and can be detected with single-molecule resolution in the cells of the transparent organisms. The Cell paper focuses on the use of PACT and PARS as research tools for studying disease and development in research organisms.
They also combined 33 new transcriptomes a set of RNA molecules with 13 genomes both
The first-principle calculations by Rice university theoretical physicist Boris Yakobson and his coauthors postdoctoral researcher Vasilii Artyukhov and graduate student Mingjie Liu show that stretching carbon chains activates the transition from conductor to insulator
Band gaps which free electrons must overcome to complete a circuit give materials the semiconducting properties that make modern electronics possible.
Each carbon atom has four electrons available to form covalent bonds. In their relaxed state the atoms in a carbyne chain would be spaced more or less evenly with two bonds between them.
But the atoms are never static due to natural quantum uncertainty which Yakobson says keeps them from slipping into a less-stable Peierls distortion. eierls said one-dimensional metals are unstable and must become semiconductors
or insulatorsyakobson says. ut it's not that simple because there are two driving factors. ne the Peierls distortion ants to open the gap that makes it a semiconductor.
which says atoms are always in motion. t s more a blur than a vibrationhe says. e can say carbyne represents the uncertainty principle in action
and may apply equally to other one-dimensional chains subject to Peierls distortions including conducting polymers and charge/spin density-wave materials.
Our technology could lead to a bomb-detecting chip for a handheld device that can detect the tiny-trace vapor in the air of the explosive s small molecules. he sensor also could be developed into an alarm for unexploded landmines that
Not only do the unstable nitro groups make the chemicals more explosive they also are characteristically electron deficient.
This quality increases the interaction of the molecules with natural surface defects on the semiconductor.
The device works by detecting the increased intensity in the light signal that occurs as a result of this interaction. e think that higher electron deficiency of explosives leads to a stronger interaction with the semiconductor sensorsays study co-lead author Sadao
and is more electron deficient than the DNT we detected in our experiments so the sensitivity of our device should be even higher than with DNTMA says.
By coupling electromagnetic waves with surface plasmons the oscillating electrons found at the surface of metals researchers were able to squeeze light into nanosized spaces
which provides information on how molecules vibrate. Scientists say the novel idea, published in the journal Analyst, could set a new gold standard for malaria testing.
The study findings identify specific molecular vibrations that help enable charge separationhe process of kicking electrons free from atoms in the initial steps of photosynthesis. oth biological and artificial photosynthetic systems take absorbed light
EXCITING MOLECULES e can carefully track what happening, Ogilvie says. e can look at where the energy is transferring
#A cheaper way to enrich super pricey isotopes Chemical elements often exist in nature as a blend of different variants called isotopes.
a single isotope has to be enriched, or separated out, from the rest. Now scientists have discovered a cheaper
and more environmentally friendly way to enrich stable isotopes, which are used for medical imaging and nuclear powernd are some of the world most expensive chemical commodities.
A combination of factors have created a looming shortage of several stable isotopes. Last year, the Government Accountability Office released a report warning that there may soon be a shortage of lithium-7
Other valuable isotopes are produced by Cold war era machines known as calutrons operating in Russia. Their extreme age
professor of physics in the University of Texas at Austin and author of the study. ne ounce of a stable isotope that needs the calutron to separate it can run around $3 million. hat roughly 2, 000 times the price
the new method for enriching stable isotopes, called MAGIS (magnetically activated and guided isotope separation), needs little energy due to its use of low-powered lasers and permanent magnets.
Many stable isotopes are precursors to the short-lived radioisotopes used in medical imaging cancer therapies, and nutritional diagnostics.
Other isotopes can be used to detect dangerous nuclear materials arriving at US ports. Now, Raizen top goal is getting this technology out of the lab and into the world.
says Raizen. here are many potential uses of isotopes that we don even know yet.
professor of chemistry at the University of Southern California and corresponding author of the paper published online in the Journal of the Electrochemical Society. ithium ion batteries degrade after around 1,
Through a combination of molecule design and trial-and-error, the scientists found that certain naturally occurring quinonesxidized organic compoundsit the bill.
and cellular respiration. hese are the types of molecules that nature uses for energy transfer, Narayan says.
the phosphorous acid reduces the copper ions to copper nanoparticles. The nanoparticles attract electrons from the silicon wafer surface,
oxidizing it and allowing hydrogen fluoride to burn inverted pyramid-shaped nanopores into the silicon. Fine-tuning the process resulted in a black silicon layer with pores as small as 590 nanometers (billionths of a meter) that let through more than 99 percent of light.
n-type which are rich in electrons and p-type which are poor in electrons. The problem? When exposed to the air n-type materials bind to oxygen atoms give up their electrons
and turn into p-type. Postdoctoral researcher Zhijun Ning Professor Ted Sargent and colleagues modeled and demonstrated a new colloidal quantum dot n-type material that does not bind oxygen
when exposed to air. Maintaining stable n -and p-type layers simultaneously not only boosts the efficiency of light absorption it opens up a world of new optoelectronic devices that capitalize on the best properties of both light and electricity.
The Tour lab with assistance from the National Institute of Standards and Technology (NIST) produced the patented material that pulls only carbon dioxide molecules from flowing natural gas
Hwang also considered metal oxide frameworks that trap carbon dioxide molecules but they had the unfortunate side effect of capturing the desired methane as well
or nitrogen atoms) to start the polymerization reaction. This would never work on simple activated carbon; the key is that the polymer forms
and propane molecules that make up natural gas may try to stick to the carbon but the growing polymer chains simply push them off he says.
or nitrogen atoms evenly distributed through the resulting porous material. The sulfur-infused powder performed best absorbing 82 percent of its weight in carbon dioxide.
For the first time researchers have detected the exciton a fundamental particle of light-matter interaction in metals. Physicists describe physical phenomena in terms of interactions between fields
and particles says lead author Hrvoje Petek professor in the physics and astronomy department at the University of Pittsburgh.
When light (an electromagnetic field) reflects from a metal mirror it shakes the metal s free electrons (the particles)
and the consequent acceleration of electrons creates a nearly perfect replica of the incident light (the reflection).
and outputs of this process but a microscopic quantum mechanical description of how the light excites the electrons is lacking.
Petek s team of experimental and theoretical physicists and chemists from the University of Pittsburgh and Institute of Physics in Zagreb Croatia report on how light
Excitons particles of light-matter interaction where light photons become transiently entangled with electrons in molecules
and Petek and his team experimentally discovered that the surface electrons of silver crystals can maintain the excitonic state more than 100 times longer than the bulk metal enabling the excitons in metals to be captured experimentally by a newly developed multidimensional coherent spectroscopic technique.
The US Department of energy (DOE) the SLAC National Accelerator Laboratory and the National Research Foundation of Korea helped support the study.
The new device that Pint and Westover have developed is a supercapacitor that stores electricity by assembling electrically charged ions on the surface of a porous material instead of storing it in chemical reactions the way batteries do.
Supercaps must be larger and heavier to store the same amount of energy as lithium-ion batteries.
when considering multifunctional energy storage systems. attery performance metrics change when you re putting energy storage into heavy materials that are needed already for structural integritysays Pint. upercapacitors store ten times less energy than current lithium-ion batteries
Sandwiched between the two electrodes is a polymer film that acts as a reservoir of charged ions similar to the role of the electrolyte paste in a battery.
These films separate molecules based on size the smaller ones such as hydrogen pass through, while larger ones such as carbon dioxide and nitrogen are slowed down. ou can have multiple membranes in a row
localized heating of the molecules leads to a temperature and pressure increase in the gas. f the incident light intensity is modulated,
or some other type of heavy molecule or it could contain high-altitude clouds that prevent the observation of what lies underneath.
As it moves along a carbon-nanotube track it continuously harvests energy from strands of RNA molecules vital to a variety of roles in living cells
and viruses. ur motors extract chemical energy from RNA molecules decorated on the nanotubes and use that energy to fuel autonomous walking along the carbon nanotube trackchoi says.
or the first time we predicted their properties using quantum mechanics. he nanocrystals are about 3 nanometers wide by 500 nanometers longor about 1/1000th the width of a grain of sandmaking them too small to study with light microscopes
uses two sheets of dissimilar materials one an electron donor the other an electron acceptor.
When the materials are in contact electrons flow from one material to the other. If the sheets are separated then one sheet holds an electrical charge isolated by the gap between them.
because they re very poor conductors. nter graphene the single-atom-thick sheet of carbon that both conducts electricity and because it s so thin allows radio frequencies to pass unhindered.
and electrons pass from one to the next with just enough resistance to produce heat as a byproduct.
The cosmic microwave background is a sea of photons (light particles) left over from the big bang that pervades all of space at a temperature of minus 270 degrees Celsiusâ##a mere 3 degrees above absolute zero.
Light from the cosmic microwave background is polarized mainly due to the scattering of photons off of electrons in the early universe through the same process by
Gravitational lensing it has long been predicted can twist E modes into B modes as photons pass by galaxies and other massive objects on their way toward earth.
The patterns can be used to map out the distribution of mass thereby more accurately defining cosmologically important properties like the masses of neutrinos tiny elementary particles prevalent throughout the cosmos.
##but would also give scientists information about physics at very high energiesâ##much higher than can be achieved with particle accelerators.
#Noble gas molecule found in remains of exploded star Astronomers have discovered a molecule in space that contains a noble gas.
The molecule argon hydride was seen in the crab nebula the remains of a star that exploded 1000 years agothe noble gases
which include helium argon radon and krypton usually do not react easily with other chemical elements
In the right circumstances however they can form molecules with other elements. Such chemical compounds have only ever been studied in laboratories On earth leading astronomers to assume the right conditions simply do not occur in space. he crab nebula was formed only 1000 years ago
As molecules spin in space they emit light of very specific wavelengths or colors called mission lines. he precise wavelength is dictated by the composition and structure of the molecule.
Studying the emission lines observed by the SPIRE instrument allows astronomers to study the chemistry of outer space.
and one of the places where we least expected to find a noble-gas based molecule. t now seems the crab nebula provides exactly the right conditions to form such molecules.
or energized with electrons stripped from the atoms in resulting intense radiation as shockwaves. These shockwaves led to the formation of the network of cool filaments containing cold molecular hydrogen made of two hydrogen atoms.
The measurements allowed the team to gauge other properties in argon molecules. inding this kind of molecule allowed us to evaluate the type
(or isotope) of argon we discovered in the crab nebulasays Gomez. e now know that it is different from argon we see in rocks on the Earth.
#New transistors offer high output at low voltage A new type of transistor could pave the way for fast computing devices that would use very low energy including smart sensor networks and implanted medical devices.
Called a near broken-gap tunnel field effect transistor (TFET) the new device uses the quantum mechanical tunneling of electrons through an ultrathin energy barrier to provide high current at low voltage.
which allowed electrons to tunnel through the barrier when desired. To improve amplification the researchers moved all the contacts to the same plane at the top surface of the vertical transistor.
A team of researchers from Penn State the National Institute of Standards and Technology and IQE a specialty wafer manufacturer jointly presented their findings at the International Electron Devices Meeting in WASHINGTON DC.
This is a quite remarkable spatial resolution. etasurfaces could make it possible to use single photonsâ##the particles that make up lightâ##for switching
While using photons would dramatically speed up computers and telecommunications conventional photonic devices cannot be miniaturized because the wavelength of light is too large to fit in tiny components needed for integrated circuits.
Optical nanophotonic circuits might harness clouds of electrons called urface plasmonsto manipulate and control the routing of light in devices too tiny for conventional lasers.
In quantum dots microscopic discs of atom-thick graphene oxide band gaps are responsible for their fluorescence and can be tuned by changing the dots'##size.
The new development reported in the journal Langmuir should help researchers studying the complex molecules
and silicon for electronicssays nanoscientist Chad A. Mirkin. he precise placement of atoms within a well-defined lattice defines these high-quality crystals. ow we can do the same with nanomaterials
research group developed the ecipefor using nanomaterials as atoms DNA as bonds and a little heat to form tiny crystals.
We are learning so many rules for calculating things that other people cannot compute in atoms in atomic crystals. he ratio affects the energy of the faces of the crystals
or in our case just stir in water all the particles will find one another and link togetherhe says. hey beautifully assemble into a three-dimensional crystal that we predicted computationally
and energy for all the particles to arrange themselves and find the spots they should be inmirkin says.
#Quantum wells flash light without magnets Spontaneous bursts of light from a solid block illuminate the unusual way interacting quantum particles behave
The semiconducting quantum wells at the center of the experiment contain particlesâ##in this case a dense collection of electrons
of which further quenched the electrons motions and made an atomlike system. The basic features were essentially the same as those known for superfluorescence in atomic systems.
Kono says superfluorescence is a well-known many-body or cooperative phenomenon in atomic physics. Many-body theory gives physicists a way to understand how large numbers of interacting particles like molecules atoms
and electrons behave collectively. Superfluorescence is one example of how atoms under tight controls collaborate
when triggered by an external source of energy. However electrons and holes in semiconductors are charged particles
so they interact more strongly than atoms or molecules do. The quantum well as before consisted of stacked blocks of an indium gallium arsenide compound separated by barriers of gallium arsenide. t s a unique solid-state environment where many-body effects completely dominate the dynamics of the systemkono says. hen a strong magnetic field is applied electrons
and holes are fully quantizedâ##that is constrained in their range of motionâ##just like electrons in atomshe says. o the essential physics in the presence of a high magnetic field is quite similar to that in atomic gases.
But as we decrease and eventually eliminate the magnetic field we re entering a regime atomic physics cannot access where continua of electronic states
or bands exist. he Kono team s goal was to keep the particles as dense as possible at liquid helium temperatures (about-450 degrees Fahrenheit)
so that their quantum states were obvious or uantum degeneratewhich happens when the so-called Fermi energy is much larger than the thermal energy.
When pumped by a strong laser these quantum degenerate particles gathered energy and released it as light at the Fermi edge:
the energy level of the most energetic particles in the system. As the electrons and holes combined to release photons the edge shifted to lower energy particles
and triggered more reactions until the sequence played out. The researchers found the emitted light shifted toward the higher red wavelengths as the burst progressed. hat s cool about this is that we have a material we excite it with a 150-femtosecond pulse wait for 100 picoseconds
and all of a sudden a picosecond pulse comes out. It s a long delaykono says. his may lead to a new method for producing picosecond pulses from a solid.
We saw something essentially the same previously but it required high magnetic fields so there was no practical application.
But now the present work demonstrates that we don t need a magnet. he team included co-lead authors Timothy Noe a Rice postdoctoral researcher and Ji-Hee Kim a former Rice postdoctoral researcher and now a research
#RNA readout tool could lead to tougher crops Scientists have developed a method that enables more-accurate prediction of how RNA molecules fold within living cells.
and Philip Bevilacqua professor of chemistry appears in Nature. cientists have studied a few individual RNA molecules
but now we have data on almost all the RNA molecules in a cell more than 10000 different RNASASSMANN says. e are the first to determine on a genome-wide basis the structures of the RNA molecules in a plant
or in any living organism. emperature and drought are among the environmental stress factors that affect the structure of RNA molecules thereby influencing how genes are xpressedhow their functions are turned turned on
by affecting the structures of their RNA molecules and so influencing their translation into proteinsbevilacqua says. he more we understand about how environmental factors affect RNA structure
Such crops which could perform better under more-marginal conditions could help feed the world s growing population. he project involved determining the structures of the varieties of RNA molecules in a plant named Arabidopsis thaliana.
RNA is the intermediate molecule between DNA and proteins in all living things. It is a critical component in the pathway of gene expression
Unlike the double-stranded DNA molecule which is compressed into cells by twisting and wrapping around proteins RNA is stranded single
and the Department of energy s SLAC National Accelerator Laboratory who led the research with Bao. The electrodes worked for about 100 charge-discharge cycles without significantly losing their energy storage capacity. hat s still quite a way from the goal of about 500 cycles for cell phones
it has a high capacity for soaking up lithium ions from the battery fluid during charging and then releasing them
To make the self-healing coating scientists deliberately weakened some of the chemical bonds within polymersâ â##long chainlike molecules with many identical units.
and quickly link up again mimicking the process that allows biological molecules such as DNA to assemble rearrange and break down.
For example four tons of material were recovered from a meteor shower in Jilin China in 1976. helyabinsk serves as unique calibration point for high energy meteorite impact events for our future studies. he work was supported by the Russian Academy of Sciences the Office
which provide a tube with a channel of around 1nm (around one millionth of a mm) â##the right size to allow small molecules
and ions to pass through. Attached to each of the cyclic peptides are two different types of polymers
which can act as molecular ievesto separate liquids and gases one molecule at a timeâ##a property that shows promise for applications such as water purification water desalination and gas storage.
and organize themselves to form pores that allow the passage of molecules of precise sizes.
In this state they could be used for the development of new drug systems by controlling the transportation of small molecules
or ions inside cells. here is an extraordinary amount of activity inside the body to move the right chemicals in the right amounts both into
and out of cellssays Sebastien Perrier professor at the University of Warwick. uch of this work is done by channel proteins for example in our nervous system where they modulate electrical signals by gating the flow of ions across the cell membranehe says.
and more efficient at harvesting energy from the sun. For solar panels wringing every drop of energy from as many photons as possible is imperative.
which excites electrons and causes them to flow in a certain direction. This flow of electrons is electric current.
But to establish a consistent direction of their movement or polarity solar cells need to be made of two materials.
Once an excited electron crosses over the interface from the material that absorbs the light to the material that will conduct the current it can't cross back giving it a direction. here's a small category of materials
however that when you shine light on them the electron takes off in one particular direction without having to cross from one material to anothersays Andrew M. Rappe professor of chemistry
Moreover it would be a way around an inefficiency intrinsic to interfacial solar cells known as the Shockley-Queisser limit where some of the energy from photons is lost as electrons wait to make the jump from one material to the other. hink of photons coming from the sun
when you catch them. f you set your limit too high you might get more value per photon
but catch fewer photons overall and come out worse than if you picked a lower denominationhe says etting your bandgap to catch only silver dollars is like only being able to catch UV LIGHT.
Most light absorbing materials have a symmetrical crystal structure meaning their atoms are arranged in repeating patterns up down left right front and back.
all directions ookthe same from the perspective of an electron so there is no overall direction for them to flow.
A perovskite crystal has the same cubic lattice of metal atoms but inside of each cube is an octahedron of oxygen atoms
and inside each octahedron is another kind of metal atom. The relationship between these two metallic elements can make them move off center giving directionality to the structure
and making it polar. ll of the good polar or ferroelectric materials have this crystal structurerappe says. t seems very complicated
which catches the most valuable photons and lets the less valuable ones pass through. Successive layers have lower and lower bandgaps getting the most energy out of each photon
but adding to the overall complexity and cost of the solar cell. he family of materials we've made with the bulk photovoltaic effect goes through the entire solar spectrumrappe says. o we could grow one material
In solid-state white lighting technology phosphors are applied to the LED chip in such a way that the photons from the blue gallium nitride LED pass through the phosphor
Until recently the preparation of phosphor materials was more an art than a science based on finding crystal structures that act as hosts to activator ions
which convert the higher energy blue light to lower energy yellow/orange light. o far there has been no complete understanding of
and others notseshadri says. n the wrong hosts some of the photons are wasted as heat
and inevitably this impacts phosphor properties adversely. ery few phosphor materials retain their efficiency at elevated temperaturesbrgoch says. here is little understanding of how to choose the host structure for a given activator ion such that the phosphor is efficient and such that
#Photon detector is quantum leap from semiconductors A new superconducting detector array can measure the energy of individual photons.
An MKID is a type of superconducting photon detector; microwave refers to the readout frequency rather than the frequency at
and arrival time of individual photons. orty years ago we were doing optical astronomy with photographic plates
which shows the arrival of each and every photon. This allows astronomers to see rapidly changing events a great advantage for many observations.
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