These findings will help in the creation of future flat and flexible electronic devices. In recent decades, physicists have been actively studying so-called two-dimensional materials.
conducts current better than copper and has good thermal conductivity. Scientists believe that other types of two-dimensional materials may possess even more exotic properties.
A group of scientists from Russia and the USA, including Pavel Sorokin and Liubov Antipina from MIPT, recently conducted research on the properties of the crystals of one such material, Nb3site6, a compound of niobium telluride
"In their structure, the crystals resemble sandwiches with a thickness of three atoms (around 4 angstroms:
which many scientists view as promising two-dimensional semiconductors. The scientists synthesized Nb3site6 crystals in a laboratory at Tulane University (New orleans.
They then separated them into two-dimensional layers, taking samples for further analysis by transmission electron microscopy, X-ray crystal analysis and other methods.
because it helped simplify the description of processes in crystals, and tracking of electron-phonon interaction is fundamentally important for description of the different conducting properties in matter."
a co-author of the study, doctor of physical and mathematical sciences, and lecturer at the MIPT Section of the Physics and Chemistry of Nanostructures (DMCP).
American colleagues confirmed this prediction in related experiments.""They conducted measurements where the same effect was observed.
#Using single molecules as sensors for ultrahigh-resolution 3d microscopy (Nanowerk News) Using a single molecule as a sensor,
The first results achieved using"scanning quantum dot microscopy"have been published in the current issue of Physical Review Letters("Scanning Quantum dot Microscopy".
The technique is relevant for diverse scientific fields including investigations into biomolecules and semiconductor materials.
A single silver atom on a silver substrate (Ag (111)) under the scanning quantum dot microscope.
Forschungszentrum Jlich)" Our method is the first to image electric fields near the surface of a sample quantitatively with atomic precision on the subnanometre scale,
Such electric fields surround all nanostructures like an aura. Their properties provide information, for instance, on the distribution of charges in atoms or molecules.
To image electric fields up until now, scientists have used the entire front part of the scanning tip as a Kelvin probe.
then the tip of the microscope would be as large as the Empire state Building. Illustration of the measuring principle:
depending on the local electric potential field of a nanostructure on the surface of a sample,
a single electron jumps from the tip of the microscope to the sensor molecule or back.
Forschungszentrum Jlich) Single molecule as a sensor In order to improve resolution and sensitivity, the scientists in Jlich attached a single molecule as a quantum dot to the tip of the microscope.
Quantum dots are tiny structures, measuring no more than a few nanometres across, which due to quantum confinement can only assume certain,
discrete states comparable to the energy level of a single atom. The molecule at the tip of the microscope functions like a beam balance,
which tilts to one side or the other. A shift in one direction or the other corresponds to the presence or absence of an additional electron
but rather two electric fields that act on the mobile electron of the molecular sensor: the first is the field of a nanostructure being measured,
and the second is a field surrounding the tip of the microscope, which carries a voltage."
we can create a very sharp image of the electric field of the sample. Its a bit like a camera with very small pixels."
"Left: The scanning quantum dot micrograph of a PTCDA molecule reveals the negative partial charges at the ends of the molecule as well as the positive partial charges in the centre.
Centre: Simulated electric potential above a PTCDA molecule with molecular structure Right: Schematic of charge distribution in the PTCDA molecule.
which is particularly suitable for measuring rough surfaces, for example those of semiconductor structures for electronic devices or folded biomolecules."
"In contrast to many other forms of scanning probe microscopy, scanning quantum dot microscopy can even work at a distance of several nanometres.
In the nanoworld, this is quite a considerable distance, "says Christian Wagner. Until now, the technique developed in Jlich has only been applied in high vacuum and at low temperatures:
Other forms of quantum dots could be used as a sensor in place of the molecule, such as those that can be realized with semiconductor materials:
one example would be made quantum dots of nanocrystals like those already being used in fundamental research h
#A new approach to develop highly-potent drugs A new study led by University of Kentucky researchers suggests a new approach to develop highly-potent drugs
which could overcome current shortcomings of low drug efficacy and multi-drug resistance in the treatment of cancer as well as viral and bacterial infections.
Published in Nanomedicine("New approach to develop ultra-high inhibitory drug using the power function of the stoichiometry of the targeted nanomachine or biocomplex),
"the study identified a new mechanism of targeting multi-subunit complexes that are critical to the function of viruses, bacteria or cancer,
thus reducing or possibly even eliminating their resistance to targeted drugs. The study was led by Peixuan Guo, director of UK's Nanobiotechnology Center and one of the top nanobiotechnology experts in the world.
Guo holds a joint appointment at the UK Markey Cancer Center and in the UK College of Pharmacy."
"Efficacy is the key in drug development, Guo said.""Inhibiting multisubunit targets works similar to the series-circuit Christmas decorating light chains;
one broken bulb turns off the entire lighting system.""By targeting RNA or protein subunits that have multiple sites for inactivation,
but that are linked inextricably, this method allows for killing or disabling the RNA or protein without requiring the inhibition of multiple pathways that might be used by the organism to remain active and viable (and thus,
or die and thus, no longer able to cause disease. ne of the vexing problems in the development of drugs is drug resistance,
former Dean of the UK College of Pharmacy and current UK provost. r. Guo's study has identified a new mechanism of efficiently inhibiting biological processes that are critical to the function of the disease-causing organism,
Guo focuses much of his work on the use of ribonucleic acid (RNA) nanoparticles and a viral nanomotor to fight cancer
viral infections and genetic diseases. He is well-known for his pioneering work of constructing RNA nanoparticles as drug carriers u
#Engineers give invisibility cloaks a slimmer design (Nanowerk News) Researchers have developed a new design for a cloaking device that overcomes some of the limitations of existing"invisibility cloaks."
"In a new study, electrical engineers at the University of California, San diego have designed a cloaking device that is both thin
"said Boubacar Kant, a professor in the Department of Electrical and Computer engineering at the UC San diego Jacobs School of engineering and the senior author of the study."
The idea behind cloaking is to change the scattering of electromagnetic waves--such as light and radar--off an object to make it less detectable to these wave frequencies.
"said Li-Yi Hsu, electrical engineering Ph d. student at UC San diego and the first author of the study,
which was published recently in the journal Progress In Electromagnetics Research("Extremely Thin Dielectric Metasurface for Carpet Cloaking").
"An extremely thin cloaking device is designed using dielectric materials. The cloak is a thin Teflon sheet (light blue) embedded with many small, cylindrical ceramic particles (dark blue.
Image: Li-Yi Hsu/Jacobs School of engineering/UC San diego) The researchers say that their cloak also overcomes another fundamental drawback of existing cloaking devices:
The researchers report that one of the keys to their cloak's design is the use of nonconductive materials called dielectrics,
which unlike metals do not absorb light. This cloak includes two dielectrics, a proprietary ceramic and Teflon,
which are tailored structurally on a very fine scale to change the way light waves reflect off of the cloak.
which works by cloaking an object sitting on top of a flat surface. The cloak makes the whole system--object
and surface--appear flat by mimicking the reflection of light off the flat surface. Any object reflects light differently from a flat surface,
The researchers used Computer-aided design software with electromagnetic simulation to design and optimize the cloak. The cloak was modeled as a thin matrix of Teflon in
which many small cylindrical ceramic particles were embedded, each with a different height depending on its position on the cloak."
"Our computer simulations show how our cloaking device would behave in reality. We were able to demonstrate that a thin cloak designed with cylinder-shaped dielectric particles can help us significantly reduce the object's shadow.""
We can change the way light waves are being reflected at will and ultimately focus a large area of sunlight onto a solar power tower, like
#Nanotechnology transforms cotton fibers into modern marvel (Nanowerk News) Juan Hinestroza and his students live in a cotton-soft nano world,
where they create clothing that kills bacteria, conducts electricity, wards off malaria, captures harmful gas and weaves transistors into shirts and dresses.
Cotton is one of the most fascinating and misunderstood materials, said Hinestroza, associate professor of fiber science,
who directs the Textiles Nanotechnology Laboratory at Cornell. In a nanoscale world and that is our world we can control cellulose-based materials one atom at a time.
The Hinestroza group has turned cotton fibers into electronic components such as transistors and thermistors so instead of adding electronics to fabrics,
he converts the fabric into an electronic component. Marcia Silva da Pinto, postdoctoral researcher, works on growing metal organic frameworks onto cotton samples to create a filtration system capable of capturing toxic gas,
as Juan Hinestroza looks on. Creating transistors and other components using cotton fibers brings a new perspective to the seamless integration of electronics
and textiles, enabling the creation of unique wearable electronic devices, Hinestroza said. Taking advantage of cottons irregular topography, Hinestroza and his students added conformal coatings of gold nanoparticles,
as well as semiconductive and conductive polymers to tailor the behavior of natural cotton fibers. The layers were so thin that the flexibility of the cotton fibers is preserved always
Hinestroza said, Fibers are everywhere from your underwear, pajamas, toothbrushes, tires, shoes, car seats, air filtration systems and even your clothes.
Abbey Liebman 10 created a dress using conductive cotton threads capable of charging an iphone.
With ultrathin solar panels for trim and a USB charger tucked into the waist, the Southwest-inspired garment captured enough sunshine to charge cell phones
and other handheld devices allowing the wearer to stay plugged in. The technology may be embedded into shirts to measure heart rate
or analyze sweat, sewn into pillows to monitor brain signals or applied to interactive textiles with heating and cooling capabilities.
Previous technologies have achieved similar functionalities but those fibers became rigid or heavy, unlike our yarns,
which are friendly to further processing, such as weaving, sewing and knitting, Hinestroza said. Synthesizing nanoparticles and attaching them to cotton not only creates color on fiber surfaces without the use of dyes,
but the new surfaces can efficiently kill 99.9 percent of bacteria, which could help in warding colds, flu and other diseases.
Two of Hinestrozas students created a hooded bodysuit embedded with insecticides using metal organic framework molecules,
or MOFS to fend off malarial mosquitoes. Malaria kills more than 600,000 people annually in Africa. While insecticide-treated nets are common in African homes
the antimalarial garment can be worn during the day to provide extra protection and does not dissipate like skin-based repellants.
Other students have used MOFS to create a mask and hood capable of trapping toxic gases in a selective manner.
MOFS, which are clustered crystalline compounds, can be manipulated at the nano level to build nanoscale cages that are the exact same size as the gas they are trying to capture.
We wanted to harness the power of these molecules to absorb gases and incorporate these MOFS into fibers,
which allows us to make very efficient filtration systems, he explains. Hinestroza always looks for new ways to employ cotton as a canvas for creating infinite modern uses.
We want to transform traditional natural fibers into true engineering materials that are multifunctional and that can be customized to any demand,
he said. We are chemists, we are material scientists, we want to create materials that will perform many functions,
but have it remain flexible and as comfortable as a t-shirt or an old pair of jeans s
#The artificial enzyme that'acts'natural (Nanowerk News) Every cell in the body (excepting gametes) contains the complete DNA of the individual it belongs to.
This means that when we want to stimulate genes to work harder to fight a genetic disease
Antonello Mallamaci of the International school for Advanced Studies (SISSA) in Trieste, who led the recently-published study
"Mallamaci and Cristina Fimiani, a student at SISSA and first author of the article, created synthetic hybrid enzymes."
"Their work takes place within the natural physiological interval: they amplify the process in a limited way,
This condition is the basis of some syndromes and neurological diseases.""If we can stimulate the remaining gene to work harder,
we can reduce the symptoms of the disease in some cases, "says Fimiani.""Hopefully our study will encourage others to repeat our research
"More in detail It was quality research that led to the publication of this study, highlighting the importance of training young researchers.
Fimiani was a student at the University of Trieste when she began this study at SISSA for her dissertation."
"The working hypothesis was unorthodox and the project was quite risky, "says Mallamaci, also her thesis coordinator."
allowing her to learn lab techniques necessary for all students in this field.""Fimiani was stubborn however,
Fimiani is continuing her studies as a graduate student at SISSA.""All of this took place without specific funding for this research project,
but rather through funds that SISSA invests in training students, "says Mallamaci.""This means that outstanding students like Cristina can take advantage of opportunities here
which can contribute to their academic and professional future
#The influence of surface structure on nanoparticle shape control (Nanowerk News) Peng Zhang, a professor with Dalhousies Department of chemistry,
leads a nanoscience research team of undergraduate and graduate students. Published this week in Nature Communications("The surface structure of silver-coated gold nanocrystals and its influence on shape control"),Zhangs teams report on the discovery of a new methodology to study nanoparticle structures.
Dr. Zhang and his Phd student Daniel Padmos examined gold and silver nanoparticles two very important materials, particularly in the future of biomedicine.
At this size, gold and silver look and behave much differently than they do used when theyre to make rings and necklaces.
Only when theyre very small do they begin to show new properties and these properties can be used in many different biomedical applications,
explains Dr. Zhang, lead author of the study. Nanogold, for example, has incredible optical properties that allow it to absorb light energy very well.
Currently only tested in mice, biomedical scientists have developed drugs with nanogold to target malignant tumours.
The nanogold attracts light emitted from laser therapies and heats up the cancerous mass, helping to destroy the tumour.
On the other hand, nanosilver could have potential applications in fighting bacterial diseases. Uncovering shape The shape of the surface of nanoparticles is key,
because different shapes lead to different properties and different properties lead to different behaviours. To better understand the potential applications of nanogold and nanosilver in the long run
scientists must first know much more about their surface structure. But, matter on the nanoscale is challenging to observe.
These nanoparticles are very difficult to study, explains Dr. Zhang, pointing out that ordinary techniques like electron microscopes dont provide the amount of detail necessary to understand whats happening on the surface of nanomaterials.
We used some pretty powerful techniques to uncover this surface structure for the first time, said Dr. Zhang.
Dr. Zhang, Padmos and their collaborators from Northwestern University and University of California, Riverside combined a powerful x-ray from a mile-sized synchrotron facility with computer modelling based on density functional theory.
By doing this the team was able to comprehensively study the surface of a nanoparticle.
In their nanomaterial system composed primarily of gold, silver and chloride, they even discovered more about how chloride interacts with nanogold
and nanosilver, keeping them stable. Its a little like cooking, explains Dr. Zhang. You throw in a bunch of ingredients,
but you need to know how they go together. Material scientists know chloride is important, but we didnt know how it stays on the surface of nanogold and nanosilver.
Our team found out how, at the atomic level. One step closer The Dal research teams methodology can now be used to study other nanomaterials
further expanding the knowledge in nanoscience research and designing the building blocks for groundbreaking discoveries in biomedical applications.
This experience invigorates my interest in this type of research, said Padmos. In the future, he plans to build upon this research to develop new functional nanomaterial systems and test their biomedical potential l
#Environmentally friendly lignin nanoparticle'greens'silver nanobullet to battle bacteria North carolina State university researchers have developed an effective
and environmentally benign method to combat bacteria by engineering nanoscale particles that add the antimicrobial potency of silver to a core of lignin,
a ubiquitous substance found in all plant cells. The findings introduce ideas for better, greener and safer nanotechnology and could lead to enhanced efficiency of antimicrobial products used in agriculture and personal care.
In a study published in Nature Nanotechnology("An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core),
"NC State engineer Orlin Velev and colleagues show that silver-ion infused lignin nanoparticles, which are coated with a charged polymer layer that helps them adhere to the target microbes,
effectively kill a broad swath of bacteria, including E coli and other harmful microorganisms. Environmentally benign nanobullet (center) attacks bacteria (left)
and neutralizes it (right). As the nanoparticles wipe out the targeted bacteria, they become depleted of silver.
The remaining particles degrade easily after disposal because of their biocompatible lignin core, limiting the risk to the environment.
People have been interested in using silver nanoparticles for antimicrobial purposes, but there are lingering concerns about their environmental impact due to the long-term effects of the used metal nanoparticles released in the environment,
said Velev, INVISTA Professor of Chemical and Biomolecular engineering at NC State and the papers corresponding author.
We show here an inexpensive and environmentally responsible method to make effective antimicrobials with biomaterial cores.
The researchers used the nanoparticles to attack E coli a bacterium that causes food poisoning; Pseudomonas aeruginosa, a common disease-causing bacterium;
Ralstonia, a genus of bacteria containing numerous soil-borne pathogen species; and Staphylococcus epidermis, a bacterium that can cause harmful biofilms on plastics like catheters in the human body.
The nanoparticles were effective against all the bacteria. The method allows researchers the flexibility to change the nanoparticle recipe in order to target specific microbes.
Alexander Richter, the papers first author and an NC State Ph d. candidate who won a 2015 Lemelson-MIT prize,
says that the particles could be the basis for reduced risk pesticide products with reduced cost and minimized environmental impact.
We expect this method to have a broad impact, Richter said. We may include less of the antimicrobial ingredient without losing effectiveness
while at the same time using an inexpensive technique that has a lower environmental burden. We are now working to scale up the process to synthesize the particles under continuous flow conditions s
#New cell division mechanism discovered (Nanowerk News) Canadian and British researchers have discovered that chromosomes play an active role in animal cell division.
This occurs at a precise stage cytokinesis when the cell splits into two new daughter cells.
It was observed by a team of researchers including Gilles Hickson, an assistant professor at the University of Montreals Department of Pathology and Cell biology and researcher at the CHU Sainte-Justine Research Centre, his assistant Silvana Jananji, in collaboration with Nelio
Rodrigues, a Phd student, and Sergey Lekomtsev, a postdoc, working in the group led by Buzz Baum of the MRC Laboratory for Molecular Cell biology at University college London.
Their findings were published today in Nature("Kinetochore-localized PP1SDS22 couples chromosome segregation to polar relaxation").
")Cell division is fundamental to all life forms: the human body develops from a single cell that divides billions of times to generate all tissue types,
and some of these cells continue to divide billions of times every day throughout life. For the moment, however, the molecular mechanisms involved are understood incompletely,
and it was unknown until now that chromosomes could play an active role at this step in cytokinesis.
Flawless division In animal cells, division involves mitosis, the separation of chromosomes followed by splitting of the cell into two new daughter cells by cytokinesis."
"Division is a complex and robust process that is generally performed flawlessly, but when an error occurs in DNA separation or during cytokinesis,
it can be a source for triggering cancer, for example, said Hickson. It is well known that microscopic cable-like structures,
called microtubules, were involved in pulling chromosomes to opposite poles of the cell during the division process.
At this time, microtubules physically separate the chromosomes via their central kinetochores while other microtubules signal to the cortex of the cell where its equator is, i e.,
, where division will take place, Hickson explained. Furthermore until now it was believed that the chromosomes only played a passive role:
that they were pulled by the microtubules and didnt affect cytokinesis, but this is not the case.
Chromosomes active role Initially working with the cells of fruit flies using powerful genetic tools and sophisticated microscopy,
the research team discovered that chromosomes emit signals that influence the cortex of the cell to reinforce microtubule action.
One of the key signals involved that the researchers identified acts via an enzyme complex a phosphatase known as Sds22-PP1
which is found at the kinetochores. They also demonstrated that this signaling pathway acts in human cells.
This is what makes fruit flies such a powerful system for helping us to understand human biology.""When chromosomes are segregated,
they approach the membrane at the poles of the cell, and thanks to this enzymes actions, this contributes to the softening of the polar membrane,
and to certain diseases, said Hickson, who has devoted the last 15 years of his research life to cell biology.
In fact, all cancers are unchecked characterised by cell division, and the underpinning processes are potential targets for therapeutic interventions that prevent cancer onset and spread.
But before we get there, we must continue to expand our knowledge about the basic processes
and signals involved in normal cell division to understand how they can go awry, or how they can be exploited..
Ultimately, this could help the rational design of more specific therapies to inhibit the division of cancer cells,
#Nanoscale light-emitting device has big profile University of Wisconsin-Madison engineers have created a nanoscale device that can emit light as powerfully as an object 10,000 times its size.
In a paper published July 10 in the journal Physical Review Letters("Extraordinarily large optical cross section for localized single nanoresonator"),Zongfu Yu, an assistant professor of electrical and computer engineering,
and his collaborators describe a nanoscale device that drastically surpasses previous technology in its ability to scatter light.
They showed how a single nanoresonator can manipulate light to cast a very large"reflection."
"The nanoresonator's capacity to absorb and emit light energy is such that it can make itself--and, in applications,
other very small things--appear 10,000 times as large as its physical size.""Making an object look 10,000 times larger than its physical size has lots of implications in technologies related to light,
amplifying itself as the surrounding environment manipulates the physical properties of its wave energy. The researchers took advantage of this by creating an artificial material in
a Ph d. student in Yu's group and lead author of the paper. Much as a very thin string on a guitar can absorb a large amount of acoustic energy from its surroundings
and begin to vibrate in sympathy, this one very small optical device can receive light energy from all around
Given the nanoresonator's capacity to absorb large amounts of light energy, the technology also has potential in applications that harvest the sun's energy with high efficiency.
In addition, Yu envisions simply letting the resonator emit that energy in the form of infrared light toward the sky,
which is very cold. Because the nanoresonator has a large optical cross-section--that is, an ability to emit light that dramatically exceeds its physical size--it can shed a lot of heat energy,
making for a passive cooling system.""This research opens up a new way to manipulate the flow of light,
This significant development in the understanding and manipulation of quantum objects is the outcome of a collaboration between Professor Stéphane Kéna-Cohen of Polytechnique Montréal, Professor Stefan Maier and research associate Konstantinos
Daskalakis of Imperial College London. Their work has been published in the prestigious journal Physical Review Letters("Spatial Coherence and Stability in a Disordered Organic Polariton Condensate".
"Microcavity To produce the room-temperature condensate, the team of researchers from Polytechnique and Imperial College first created a device that makes it possible for polaritons-hybrid quasiparticles that are part light
and part matter to exist. The device is composed of a film of organic molecules 100 nanometres thick,
confined between two nearly perfect mirrors. The condensate is created by first exciting a sufficient number of polaritons using a laser
Konstantinos Daskalakis, Imperial College London) Quantum objects visible to the naked eye Quantum mechanics tells us that objects exhibit not only particle-like behaviour,
These are at the root of some of quantum physics'most fascinating phenomena, such as superfluidity and superconductivity.
"Unlike work carried out to date, which has used mainly ultracold atomic gases, our research allows comprehensive studies of condensation to be performed in condensed matter systems under ambient conditions"explains Mr. Daskalakis.
the team of researchers from Polytechnique and Imperial College first created a device that makes it possible for polaritons-hybrid quasiparticles that are part light
The device is composed of a film of organic molecules 100 nanometres thick confined between two nearly perfect mirrors.
"To date, the majority of polariton experiments continue to use ultra-pure crystalline semiconductors, "says Professor Kéna-Cohen."
"Our work demonstrates that it is possible to obtain comparable quantum behaviour using'impure'and disordered materials such as organic molecules.
This has the advantage of allowing for much simpler and lower-cost fabrication.""The size of the condensate is a limiting factor
Toward future polariton lasers and optical transistors In a condensate, the polaritons all behave the same way, like photons in a laser.
Powerful transistors entirely powered by light are another possible application. The research team foresees that the next major challenge in developing such applications will be to obtain a lower particle-condensation threshold
Fertile ground for studying fundamental questions According to Professor Maier, this research is also creating a platform to facilitate the study of fundamental questions in quantum mechanics."
Professor Kéna-Cohen concludes:""One fascinating aspect, for example, is the extraordinary transition between the state of non-condensed particles and the formation of a condensate.
Overtext Web Module V3.0 Alpha
Copyright Semantic-Knowledge, 1994-2011