2/28/11
McGill University researchers have made a cheap, portable, paper-based filter coated with silver nanoparticles to be used in emergency situations which needs clean drinking water.
Silver
Silver has is a precious metal used to make ornaments, jewelry, high-value tableware, utensils and currency coins, nowadays in electrical contacts and conductors, in mirrors and in catalysis of chemical reactions. Its compounds are used in photographic film and dilute silver nitrate solutions and other silver compounds are used as disinfectants and micro biocides.
Silver has been used to clean water for a very long time by keeping water in silver jugs in ancient days. According to Jeffrey Ellis, Adjunct Professor of Chemistry at Florida International University in Miami, the use of silver as a water treatment by business and industry is on the rise. The global community is now rapidly moving toward using silver as a safe and effective treatment for drinking water worldwide.
Nanosilver
Nanosilver is silver (Ag) in suspension with pure de-ionized water. Approximately 80% of the silver is in the form of metallic silver nano-particles. The remaining silver is in ionic form. Though similar to colloidal silver, generally, a colloid is a suspension of particles of from 10 nm to 1 micron in diameter and the silver particles in Nano-Silver are less than 2 nm in diameter and therefore too small to be considered in "colloidal" suspension. They are rather, in a "nano-suspension," a much more stable state.
Nano Silver Antibacterial Powder is used in ceramic (enamel) products, fabric, plastic products, pigment, coin, check, wallpaper glue, architectural structure glue, and wallpaper, etc.
Nanosilver cleans water
Eventhough silver is used to get rid of bacteria in a variety of settings, from bandages to antibacterial socks, no one has used it systematically to clean water before.
McGill's Department of Chemistry researchers have coated thick (0.5mm) hand-sized sheets of an absorbent porous paper with silver nanoparticles to get rid of bacteria. The researchers poured live bacteria through the treated paper and when viewed through an electron microscope, the paper had only silver dots all over even when the contaminated water goes through. The results indicated that even when the paper contained a small quantity of silver (5.9 mg of silver per dry gram of paper), the filter was able to kill nearly all the bacteria and produce water that meets the International water quality standards.
The researchers claim that the filter is not a routine water purification system, but is a way of providing rapid small scale purification system under emergency situations. According to the researchers it works well in the lab but needs to improved and developed for the practical use.
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2/27/11
Various gold nanoparticle shapes such as spheres, rods, wires, and cubes have been prepared and characterized using standard processing techniques by researchers. By varying the shape of the materials, their vibrant optical properties can be suitably tuned from the visible to the IR region of the spectrum. Also enhanced plasmonic properties make Au nanorods of interest for a variety of sensing and biological applications.
Synthesis
Seed mediate process
As per a method outlined in the literature, Au nanorods are synthesized in a two-step seed mediate Process. In this method the surfactant cetyltrimethylammonium bromide (CTAB) is used as a surface passivant. In this mechanism, Au nanoparticle seeds are introduced to a growth solution containing excess CTAB and HAuCl from which the nanorods are grown off the surface of the seeded nucleates. The final rod-like structure possesses a surfactant bilayer on the surface, thus imparting a significant positive charge to the materials, which is the driving force for this solution stability.
Layer-by-layer assembly
The layer-by-layer (LBL) assembly method, combined with the seeded growth technique, has been used to deposit gold shells on the surface of hematite (α-Fe2O3) spindles. The LBL method yields dense coatings of preformed Au nanoparticles, while AuCl−4 ions are further reduced by a mild reducing agent, thicker, rough nanostructured shells can be grown.
Green synthesis
Gold nanorods can be prepared by electrochemically reducing gold salts in a concentrated surfactant solution.
Georgia Tech University researchers describe a wet or 'green' synthesis procedure for the synthesis of gold nanorod (Au NR). The procedure uses Silver nitrate, Ascorbic acid, Sodium borohydride, seed solution, gold solution, & CTAB. Electro deposition methodUsing another procedure, stable Au nanorods with a unidirectional pin-like morphology have been prepared on the surface of glassy carbon electrodes via a potential-step electro deposition method from H2SO4 solution containing Na[AuCl4]. In the presence of cysteine as an additive, there is significant enrichment of Au(100) and Au(110) facets in contrast to the spherical Au nanoparticles deposited in the absence of cysteine.
Uses of gold nanorods
By varying the shape of the materials, their vibrant optical properties can be suitably tuned from the visible to the IR region of the spectrum. Also enhanced plasmonic properties make Au nanorods of interest for a variety of sensing and biological applications. Gold nanorods are useful for the formation of many functional composite materials, for example, with hydrogel, polymers, silica, and bacteria. Gold nanorods also have an axial surface plasmon resonance (SSPR), though one-third that of the LSPR, is still many orders of magnitude greater than quantum dots and nanoshells. Gold nanorods also offer advantages of good biocompatibility, facile preparation, and conjugation with a variety of biomolecular ligands, antibodies, and other targeting moieties. They have therefore found wide applications in biochemical sensing, biological imaging, medical diagnostics, and therapeutics. Further, gold nanorods have found application in materials and optics, including polarizers, filters, and to improve the storage density in compact disks.
2/27/11 1
2/26/11
Gold has long been known to have size-dependent catalytic activity. The metal is inert in bulk, whereas gold nanoparticles 3 to 5 nm in diameter can catalyze a variety of reactions. But those larger nanoparticles require the addition of H2 or peroxide species to drive the reaction, or an electronic interaction with a support material such as titanium dioxide.
Nanogold
Nanometre-scale gold particles are currently intensively investigated for possible applications in catalysis, sensing, photonics, biolabelling, drug carriers and molecular electronics. Supported nanosized gold particles have shown remarkable catalytic properties even for the oxidation of CO. There are potentials for exploitation of gold nano particles for a variety of applications including environmental pollution abatement, sensors and various other chemical and biochemical applications.
Structural details explored
The chemical process of preparing such particles is well known and many different stable sizes and compositions are also known. But the definite information of their atomic structure is not well known but for the work at Stanford University and University of Jyväskylä in Finland.
Researchers in the Department of Chemistry and the Nanoscience Center (NSC) at the University of Jyväskylä, in collaboration with the Kornberg group, report the first full spectroscopic characterisation of the absorption of electromagnetic radiation by the Au102(p-MBA)44 particle in solution and solid phases. The work also establishes the molecular nature of the clusters.
Researchers in the Department of Chemistry and the Nanoscience Center (NSC) at the University of Jyväskylä, in collaboration with the Kornberg group, report the first full spectroscopic characterisation of the absorption of electromagnetic radiation by the Au102(p-MBA)44 particle in solution and solid phases. The work also establishes the molecular nature of the clusters.
2/26/11 0
Samsung Electronics claims to have produced the first large-area, full-colour display based on red, green and blue quantum dots. Making a colour display with the dots requires their deposition onto a substrate in a well-controlled manner.Structure
The dots contain a zinc sulphide shell that confines electrons and holes to the core of the structure made of a cadmium-based compound. Both charge carriers are restricted in all three spatial dimensions on length scales which restricts the energies of electrons and holes to a finite set of values, so that when these carriers reach their lowest energy state, they recombine to emit light having very narrow emission profile.
Display
Monochrome displays can be made by spin-coating. This is done by dropping a dot-containing solution onto a substrate and spinning this around to yield a thin film of material. This approach is unsuitable for making a full-colour display, because it would cross-contaminate red, green and blue pixels. Higher resolution displays are possible by reducing pixel size. Huge size printing onto flat or curved surfaces is possible by scaled up Transfer-printing to even in the shape of rolled plastic sheets.
2/23/11
Nanocomposite A nanocomposite is as a multiphase nanosolid material or structures having nano-scale repeat distances between the different phases that make up the material. It includes porous media, colloids, gels and copolymers, but is more usually taken to mean the solid combination of a bulk matrix and nano-dimensional phases differing in properties due to dissimilarities in structure and chemistry. These nanomaterials have various functional expressions due to the quantum size effect.
Nanocomposite synthesis
Various synthesis strategies have been developed such as co precipitation,flame hydrolysis, impregnation, and chemical vapour deposition, sol-gel and non-hydrolytic sol-gel routes for the synthesis of nanocomposites. Current technologies available for the manufacture of functional nanopowders are dispersion, mixing (normal, ordered or precision), coating, fusion, reactions (solid-solid surface), Mechano Chemical Bonding (MCB), shape control, agglomeration, nanogrinding and drying from nanoslurries. Once nano sized materials are produced either in liquid or gas phase, elements of classical powder technologies are applied to further process them. These processes can involve drying, blending or agglomeration of the particulates.
Mechano Chemical Bonding
This technique can modify the shape of dry particles and bond them together using mechanical energy alone without any binders. It is reported to be an environmentally friendly process. It overcomes powder mixing problems caused by the segregation and agglomeration of particles and allows each component in the composite powder to express its inherent designed function. MCB Technology is a unique dry particle processing technique that enables the use of nanoparticles to create multi-functional nanocomposites contributing to the development of advanced devices for energy storage applications.
Merits of MCB treatment
By applying the MCB treatment, powders can achieve particle coating, precision mixing, sphericalization, and surface modification in one processing step. The MCB process can practically produce any type of composite powders without the constraint of chemical compositions. Depending on the particle size and mass ratio of guest and core particles, core-shell type of composite particles or core particles with embedded guest particles can be fabricated.
Principle
The basic Principle is based on Hosokawa Mechanical Treatment. The unit contains a press head, rotating casing, inside of which powder is supplied. Due to centrifugal force and rotation of casing, powders can achieve particle coating, precision mixing, sphericalization and surface modification in one processing step. The MCB technique takes the advantages of passing dry powder mixtures with preferred particle size ratios through a narrow gap, so that smaller guest particles are bonded onto the surface of larger core particles under the influences of various types of mechanical forces. By this principle solid-solid composite materials can be produce in a dry process without the use of a binder by only applying mechanical force. It is also a multi-functional processing method for precision mixing, particle surface modification and shape enhancement.
MCB treatment for Lithium-ion batteries
To cite an example of the application of MCB technique, the development of new generation materials for rechargeable batteries for the energy storage applications can be considered. However, in addition to the chemistry of electrode materials, the energy density, power density, rate capability and cycle life of rechargeable batteries can be improved by controlling the size, morphology, and surface properties of the particulate materials used in the electrodes. Mechano Chemical Bonding is a unique technology that can effectively improve the performance of Lithium-ion rechargeable batteries. It treats powders to increase electrode densities and to reduce the required amount of organic solvent and carbon black used in the battery manufacturing. Lithium-ion rechargeable batteries made by MCB treated powders can exhibit high capacity, long cycle life, and low internal ohmic resistance at high discharge rate.
2/23/11 0
2/22/11
Computers of higher capacities of increased efficiency at reasonable costs are essential for handling and processing huge data. Researchers from German-French research team have succeeded in this direction. This has been done by combining the concepts of spin electronics and molecular electronics in a single component consisting of a single molecule.Magneto resistance
Magneto resistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied to it. The property of magneto resistance is used in reading the bits on magnetic tape and disk. The physical origin of the magneto resistance effect lies in spin orbit coupling. The electron cloud about each nucleus deforms slightly as the direction of the magnetization rotates, and this deformation changes the amount of scattering undergone by the conduction electrons when traversing the lattice.
The ferromagnetic material utilized for Anisotropic Magneto Resistance (AMR) heads is NiFe (permalloy). This is because of the relatively large effect at room temperature and the low saturation fields required for obtaining the AMR effect. In recording heads, the geometry is such that the field from the media is transverse to the current direction in the head.
Giant Magneto resistance
Giant magneto resistance (GMR) occurs in structures containing ferromagnetic contacts separated by a metallic non-magnetic spacer, and is now the basis of read heads for hard drives and for new forms of random access memory. Such components allow for the production of very small and highly efficient magnetic field sensors for read heads in hard disks or for non-volatile memories in order to further increase reading speed and data density.
Very weak magnetic changes give rise to major differences in electrical resistance in a GMR system. A system of this kind is the perfect tool for reading data from hard disks when information registered magnetically has to be converted to electric current. Even the most recent read-out techniques of today are further developments of GMR and are considered as one of the first real applications of the promising field of nanotechnology.
Spin electronics
In spin electronics, the information is encoded in the intrinsic spin rotation of the electron. This spin is maintained even when switching off current supply, which means that the component can store information without any energy consumption.
2/22/11 0
2/20/11
Pathogen identification is an important process in control and eradication. At present, to identify a variety of them such as biological weapons, bacteria such as anthrax, a virus such as smallpox, or a toxin such as botulism, samples must be collected and cultured in controlled laboratories. A new system has been developed using nanowire sensors which is very compact and works virtually instantaneously.Mechanism
The core of this portable bio weapon recognition system is an amalgamation of tiny wires, which are about 250 nanometers around and 6,000 nanometers long and assortment of antibodies, the proteins that the body produces to directly attack, or direct the immune system to attack, cells that viruses, bacteria, and other unpleasant intruders infect.
Construction
Each type of pathogen calls for a unique antibody. The tiny wires made by an independent company are electrochemically formed and then layered with bands of silver, gold, and nickel to produce patterns that are similar to the ubiquitous barcodes found on products worldwide. Then antibodies are essentially glued to the miniscule wires.
For example, say anthrax antibodies are attached to nanowires with one code and smallpox antibodies are attached to nanowires with another forming a pool of various striped nanowires each of which will have a unique antibody assigned to it for the detection of particular pathogen.
Working
To identify pathogens, millions of bar-coded, antibody-carrying nanowires are floated in a neutral liquid called an assay buffer, into which samples of suspected pathogens are injected. If a pathogen meets its corresponding antibodies, they will join creating nanowires, antibody, antigen sandwich that will fluoresce, or glow, under a special light. To identify individual pathogens, the system takes two digital mug shots in quick succession. In the first the special light is off, and the barcodes are visible. In the second the light is on and the pathogen-fingering nanowires are glowing. A computer then matches each glowing wire in the second photo to its barcode. The advantage of the system is that many kinds of bar-coded antibodies can be mixed together in the assay buffer liquid and can be reused.
2/20/11 0
Self-cleaning fabrics could revolutionize the sport apparel industry. Scientists of the U.S. Air Force have created t-shirts and underwear that can be worn hygienically for weeks without washing. This is done by attaching nanoparticles to clothing fibers using microwaves. Then, chemicals that can repel water, oil and bacteria are directly bound to the nanoparticles. These two elements combine to create a protective coating on the fibers of the material. This coating both kills bacteria, and forces liquids to bead and run off. This technology was originally developed for U.S. military to protect soldiers from biological weapons and to avoid casualties from bacterial infections due to wearing of underwear for several weeks.2/19/11
Researchers have discovered that carbon fibers in composites can be made stronger and tougher by coating the with additional microscopic carbon nanotubes. This process can be used to make critical aircraft components and other machinery nearly unbreakable. Carbon is in its crystalline form has very high strength and hardness and as nanocarbon fiber is even stronger than steel. But when it comes to making more rigid structures such as airplane parts, carbon fiber has to be sandwiched in alternating layers with epoxy resin, and this resin becomes the weak link in the overall laminate. But high stress can make it to fracture, which can be disastrous for an aircraft in flight. Interlaminar fracture can be completely avoided using carbon fibers in composites by coating the with additional microscopic carbon nanotubes.High temperature strength
Researchers at University of California have developed a process for metals to be stabilized and strengthened, especially at high temperatures, by the addition of diamondoid. Diamondoid materials for nanotechnology include graphite, carbon nanotubes consisting of sheets of carbon atoms rolled into tubes, spherical buckyballs and other graphene structures. Such nanocrystalline alloys can provide superior mechanical and electrical properties than their coarse-grained counterparts. The process readily produces fine grained and nanocrystalline metals and alloys of greater high temperature strength and stability.
2/19/11 0
High-performance upholstery finishes based on nanotechnology find applications in health care facilities, sporting arenas, airports, educational facilities, hotels, restaurants, casinos and cruise ships. Encasing fabric in thick layers of chemicals is one of the old techniques to get Spill and stain proofing.Spill and stain proofing
One of the successful nanotechnology applications to interior textiles is based on the use of nanowhiskers which could be permanently attached to textiles wherein hooks of the nanowhiskers are bonded to fibers to provide enhanced, durable resistance to spills and stains. Nanotechnology is used to build permanent spill and stain resistance into the fiber structure of the fabric. It bonds with the fibers rather than making a coat, protecting the material from dirt without depriving it of air at the atomic level. Spills become beads and roll over the surface.
Researchers have recognized that it is not the smoothest possible surfaces but those with structures measuring some dozens of nanometers that repel dirt and water most effectively. This principle is practically implementation on textiles.
This is done by optimizing the processing and durability of the finishing using a composite material consisting of nanoparticles firmly embedded in a carrier matrix.
A New Zealand company is commercializing nano-fabrics made from the collagen in discarded fish skins. The thin fibers are exceptionally strong and provide extra filtration capabilities due to their nano-properties, and use them in everything from clothing to filtration systems, structural reinforcement, electronics, biodegradable air filter mat and packaging and building a commercial-scale nano-loom to create the fabrics.
2/18/11
Factories across the world are dumping thousands of tonnes of untreated dyes into rivers and waterways every year. The majority of these dyes are toxic to the environment and may lead to mutations and cancers in animals. Particularly in textile industries where considerable amounts of water and chemicals are used during the dyeing process the wastewater contains about 20% of dye as well as organic matter, salts and other substances. Also since synthetic dyes are used to resist bleaching by UV-light and chemicals to improve the quality of the textiles, they are also persistent in the environment and some dyes can be biologically modified into carcinogenic compounds. For example azo dyes, a commonly used dye to color fabrics can cause cancer if released into the environment with wastewater.
Removal of color from dye wastewater
The release of untreated wastewater has high color, high chemical oxygen demand, low biodegradabilityand high variability, it poses a threat to the animal and human health, environment and the most serious problems are ground water and surface water pollution. Further, the discharge of colored effluents into water bodies affects the sunlight penetration which in turn decreases both the photosynthetic activity and dissolved oxygen levels. The removal of dyes from wastewater is one of the major environmental challenges.
Removal techniques
Wastewater containing dye is conventionally filtered using activated carbon. However, the carbon can only be used once and is then commonly disposed of in landfill sites. Biotechnological treatment methods called dye remediation can be used for the treatment of dyes using biological and physico-chemical techniques. Different techniques are adopted to treat dye wastewater including adsorption, catalytic oxidation, chemical oxidation, photocatalysis, electrochemical process, biodegradation and catalytic wet oxidation by adding catalysts and oxidants to improve the oxidation rate.
Catalytic wet oxidation
Catalytic wet oxidation
Catalytic wet oxidation process is usually carried out at high temperature and pressure, which restrict its wide application. More and more efforts have been focused on developing new processes to improve the efficiency of CWO, such as the preparation of new type heterogeneous catalysts with high catalytic activity. CeO2 or CeO2-based oxides materials by virtue of their large surface area exhibit greater catalytic activity in CWO.
Recovery
It is very hard to recover pure CeO2 or CeO2-based oxides powders from water when they are used in aqueous systems. Coating the particles onto other materials is the promising method to resolve this problem. Supports of silica and γ-Al2O3 have been used to prepare the CeO2-based catalysts, but, the supports, synthesized by chemical reactions have inherent defects such high cost, time consuming reaction and low surface area.
Natural nanostructural material
Attapulgite (ATP) is a crystalline hydrated magnesium aluminum silicate with reactive –OH groups on its surface with a structure of zeolite-like channels. Due to its regular structure and large specific surface area, ATP has been used as absorbent, catalyst and catalyst support. Zhao et al. prepared copper modified palygorskite/TiO2 photocatalyst by hydrolysis method, which exhibited much higher activity than that of the pure titanium dioxides in the degradation of methylene blue. In addition, it was reported that the redox couple (Ce3+/Ce4+) in contact with metal particles promoted the catalytic activity in ceria-based materials. It is effective way to enhance the catalytic reaction rate that modified the palygorskite clay with copper ions since addition of rare metal ions to CeO2-based catalytic systems.
2/18/11 0
The process of destroying microorganisms is called sterilization and removing all pathogenic agents from objects is termed as disinfection. Heat, chemicals, irradiation, high pressure or filtration are commonly used to remove microbes from surfaces, medical appliances, linen etc., to perform a sterilization and disinfection. To contain the pathogenic organisms is a main concern of health care or in the process of food production and consumption.
But increased resistance of many pathogenic species is reported to the commonly used disinfectant and antibiotics. Hence new types of safe and cost-effective antimicrobial active materials are needed by this sector. Reported studies indicate that various nanomaterials exhibit excellent antimicrobial properties.
Activity
Nanomaterials may interact with cellular wall and disintegrate it. They can accumulate inside the cell or may lead to ROS (reactive oxygen species) production, thus to destroy the cell integrity. The cytotoxic mechanism is via DNA damage.
Materials
Silver compounds and silver ions that have been recognized as active antimicrobial agents. Silica spheres with silver nanoparticles and Ag-Au doped material prepared by the cementation process are few active antimicrobial agents. Ag-SiO2-Au doped nanomaterials demonstrated antibacterial activity.
Silver and silver-gold doped silica nanospheres revealed antibacterial activity against Escherichia coli. For the higher nanoparticles concentration, the antimicrobial effectiveness was higher.
Researchers from Wroclaw University of Technology, Poland have reported that sol-gel route is a very convenient method to produce various materials and it is frequently exploited for nanomaterials. Composite materials in the form of nanopowders may be produced or they may be deposited on various substrates, e.g. fibers, metals etc. The photocatalytic properties of such materials may be used for photosterilization processes. Moreover, it is possible to apply not only UV but the light in visible range.
Creating alternate fuels, cleaning the environment, dealing with the causes of global warming, and keeping safe from toxic substances and infectious agents are the new challenges faced by humanity. To combat all these problems hydrogen is claimed to offer a potential solution for satisfying many of our energy needs while reducing and eventually eliminating carbon dioxide and other greenhouse gas emissions. Water-gas-shift is one of the important reactions by which hydrogen is produced from most of the synthetic gases.Water-gas-shift reaction
In the water-gas-shift (WGS) CO and H2O are converted into CO2 and H2 by the reactions:
CO + H2O → CO2 + H2, and
2CO + O2 → 2CO2
It is primarily used to produce higher H2 content and to reduce the CO content of syngas. The WGS reaction has gained more interest due to its application for onboard purification and production of H2 for fuel cell vehicles. For industrial operations, Cu-based catalysts are used for of the WGS reaction which occurs at temperature range of 470 - 520K.
WGS catalysts
Although WGS catalyst have been used commercially for many decades, the conventional catalysts are not sufficient to meet the rigorous performance targets required for fuel processor systems.
But when used for automotive applications, Cu-based catalysts result in condensation of water and need subsequent deactivation treatment of the catalysts. Copper based WGS catalysts have been shown to be very active when precipitated with zinc and aluminum oxide or when supported on cerium. However copper catalysts remain to be very sensitive to sulfur poisoning whereas precious metal catalysts are somewhat tolerant. This makes a need for the development of advanced WGS catalysts that include high activity and stability.
Nano catalysts
Researchers have shown that Au or Cu nanoparticles supported on the oxides, such as CeO2 and TiO2, possess higher activity even better than commercial catalysts in the WGS reaction where as bulk gold, ceria, and titania are not known as WGS catalysts.
CeriaCerium oxide (CeO2) / ceria are an important inorganic material having the cubic fluorite type crystal structure. Ceria either in the pure form or doped with other metals (Cu, Ni, etc) / metal ions (Mg2+, La2+, Sc2+, Gd3+, Y3+, Zr4+ etc.), potentially has a wide range of applications including gas sensors, electrode materials for solid oxide fuel cells, oxygen pumps, amperometric oxygen monitors and three way catalytic supports for automobile exhaust gas treatment. The nanoceria has attracted much attention because of the improved physical and chemical properties compared to the bulk ceria material.
Synthesis of CeO2 based nanoparticles
Solution based techniques are used for the synthesis of pure ceria and transition metals, rare earth metals, or metal ions doped ceria materials. Various synthesis routes include co precipitation, hydrothermal, microemusion, solgel, combustion of aqueous solutions of the metal acetate without addition of any extra fuel in a methane oxygen flame and electrochemical methods. In these methods several steps have to be followed, more time will be taken for the completion of reaction or control of the product composition may be difficult.
Researcher Pati and his associates give the following procedure.The precursors used were; cerium acetate as the cerium source, copper acetate as the copper source, nickel acetate as the nickel source and iron acetate as the iron source. The precursors were dissolved in deionized water to make solutions of each. The solutions were filtered through a membrane filter before filling the nebulizer. Liquid precursor feed was then atomized with compressed air resulting in a fine spray. In the reactor the flame was made by methane, oxygen and nitrogen and the flow rate of gas and precursors were controlled. After burning the fine spray, the particles were collected on a water-cooled surface.
Uses of Cerium
Cerium oxide (CeO2) is widely used as a promoter and an oxidation catalyst because of its unique redox properties and high oxygen storage capability. Cerium oxide has potential applications for UV blocks, polishing materials, the three-way catalysts and in solid oxide fuel cell. In addition, supported CeO2 and CeO2-based mixed oxides are effective catalysts for the oxidation of different hydrocarbon and for the removal of organics from wastewater from different sources.
Gold ceria or titania nanoparticles
Researcher Rodriguez and associates have found a good performance of Au-CeO2 and Au-TiO2 catalysts in the water-gas shift reaction. Although gold is not catalytically active for the WGS, gold surfaces that are 20 to 30% covered by ceria or titania nanoparticles have activities comparable to those of good WGS catalysts. In TiO2-x/Au(111) and CeO2-x/Au(111), water dissociates on O vacancies of the oxide nanoparticles, CO adsorbs on Au sites located nearby, and subsequent reaction steps take place at the metal-oxide interface.Researcher Nan Yi and associates studied steam reforming of methanol over ceria and gold-ceria nanoshapes and found that a small amount of gold deposited on ceria nanorods exhibited excellent catalytic activity for the low-temperature steam reforming of methanol. Gold clusters dispersed on the faces of ceria nanorods catalyze the reaction in a cooperative mechanism with ceria.
Mechanism
Neither CeOx/TiO2(110) nor Au(111) was able to catalyze the WGS. However, Au/CeOx/TiO2(110) surfaces are outstanding catalysts for the WGS. The deposition of gold NPs on CeOx/TiO2(110) yield surfaces with an extremely high catalytic activity for the water–gas shift reaction and the oxidation of CO.In principle, the combination of two metals in an oxide matrix can produce materials with novel structural and/or electronic properties. At structural level, a dopant can introduce stress into the lattice of an oxide host, inducing in the formation of defects.
Ceria and titania adopt different crystal lattices in their most stable bulk phases, fluorite and rutile, respectively. Within the fluorite structure each Ce atom is bonded to 8 O atoms, whereas 6 O atoms surround the Ti atoms in the rutile structure. One of the most interesting properties of ceria is its ability to undergo a conversion between “+4” and “+3” formal oxidation states. The surface chemistry and catalytic properties of CeO2 depend on the formation of Ce3+ ions.
2/14/11
Charge-transfer nanocomposites (CTNs) are blends or composites of quantum-functional nanophase materials; such as carbon nanotubes, quantum dots, and fullerenes with electro active conjugated polymers. These materials exhibit distinctive properties over polymer-polymer blends, in particular enhanced electro activity, photoemission, and photo absorption.
CTNs in their various guises have been extensively used for highly efficient organic light-emitting diodes, highly conductive thin films, and, more recently, efficient organic photovoltaics, but advances have been limited because technology suffers from extreme sensitivity to the environment, including oxidation, delamination of contacts due to water and limited by carrier mobility and optical coupling.
But today's polymer photovoltaic devices are closing the gap between potential performance and actual efficiency and have achieved record photovoltaic conversion efficiencies of nearly double the previously reported values. This is due the ordered placement of nanostuctures into architectures that extend over many microns called mesoscale ordering. This placement of nanomaterials into three-dimensional arrays referred to as ‘scaled structures’ or ‘hierarchical structures’ have provided a powerful new tool for developing high-performance photovoltaics.
These more efficient devices are possible with a disordered array of solubilized fullerenes dispersed in a P3HT thin film device. Such materials when annealed to a temperature approaching the glass transition of the polymer the polymer crystallizes, and hole mobilities within the polymer phase increase dramatically forming high-aspect- ratio nanocrystalline grains of PCBM (nanowhiskers) in the matrix giving conversion efficiency nearly 45% of the theoretical maximum for this host material.
2/14/11 0
Iron oxide nanowhiskers
Iron oxide nanowhiskers with dimensions have been synthesized by selectively heating an iron oleate complex. Such nanostructures resulted from the difference in the ligand coordination microenvironments of the Fe(III) oleate complex. A ligand-directed growth mechanism is proposed to rationalize the growth process of shape-controlled nanostructures for the formation of the nanowhiskers.
C60 nanowhiskers
C60 nanowhiskers can be formed by the liquid-liquid interfacial precipitation technique which is a low-cost means of fabricating nano-structured fibres. C60 nanowhiskers can be used as active or passive elements in a number of possible applications in electronic devices with switching or sensing capabilities, low-cost, robust millimeter-wave power detectors.
Nanotube whiskers
Researchers at Massachusetts Institute of Technology in Cambridge have developed a chemical process in which carbon fibers, heated to 750° C, sprout nanotube whiskers. They then wove those stubbly fibers into a fabric, which they injected with epoxy. The nanotubes tied the layers together and created a Velcro-like effect.
Silicon nanowhiskers
When a wafer of silicon is slowly heated under high vacuum conditions, the structure of the silicon rearranges itself to form tiny little pillars of silicon of around 10nm high and self-assemble all over the surface so that one square cm might have four billion nanowhiskers. Since the tips of the nanowhiskers are very sharp, it only takes a small field to induce the whiskers of very high density. This makes them suitable for using in low field electron emitters of small and light size suitable for use in portable devices like computer displays and widescreen televisions.
Making silicon nanowhiskers
Nanowhiskers are fabricated using GNS process as follows.The Si(100) substrate (either p-type or n-type) is cleaned to remove any surface dust or dirt but the native oxide layer is not removed, so this stage is very simple and quick. In some cases ions are implanted into the surface and the substrate is inserted into a high vacuum chamber and heated using a raster scanned electron beam that scans over the substrate at high speed, heating it in a homogeneous way. The sample is slowly raised to a peak temperature of 900- 1100C and held for a few seconds and then cooled again. The substrate is removed from the vacuum at room temperature to get nanowhiskers covered over it.
Nanowhiskers formation
Nanowhisker formation occurs in a two-stage process. Firstly, decomposition of the native oxide layer occurs. Voids form in the oxide film exposing clear silicon underneath. Silicon from the voids reacts with the oxide layer and the voids grow laterally until they coalesce. This causes a roughening of the surface and an uneven surface potential energy. After complete oxide adsorption Si species begin to migrate across the surface to kinetically favoured sites or nucleating islands. Island number and size grows as the annealing continues resulting in the growth of crystalline pillars.
Sic whisker powder
Sic whisker powder are available at a purity of 99%, diameter 1-2.5micron, L/D>=20 and in cubic crystal figure.Sic whisker powder has the good chemistry stability, low heated expansion, and high efficiency of heat conductivity, electrical resistance compared with metal being in the opposite direction and very hard. Sic resists heat, grinding and crushing, especially in resisting hot shock wave, corrosion and radiation. It is used for the fuselage cover of shuttle space craft, ceramics cutting tools, measurement tools and mould, for functional ceramics, bullet-proof ceramics and piezoelectric ceramics, ceramic bearings, far-infrared ray generator, spray nozzles, radiant tubes and combustors on machine.
ZnO nanowhiskers
Researchers report that vvertically aligned ZnO nanowhiskers can be grown on Si substrates spin-coated with ZnO nanoparticles by metal organic chemical vapor deposition (MOCVD) using Me2Zn•tmeda and a mixture of O2 and Ar gases. The ZnO nanowhiskers grown are single crystals with a growth rate of 3 μm h−1.
Blanket-like assembled ZnO nanowhiskers were fabricated using a freestanding ZnO nanoparticle layer by an aqueous solution deposition. Thermal treatment of the zinc acetate dihydrate layer resulted in the formation and delamination of the ZnO nanoparticle layer on the glass substrate. The growth habits of ZnO crystals resulted in the growth of ZnO nanowhiskers preferentially orientated along the direction of the c-axis on the whole surface of the freestanding ZnO nanoparticle layer by heterogeneorous nucleation and growth. The hierarchical-structured blanket-like ZnO nanowhisker assemblies can be utilized for dye-sensitive solar cells and gas sensors because of their high surface-to-volume ratio.
Single crystalline GaAs whiskers
Researchers have carried out under carefully selected conditions the hetero-epitaxial growth of branched III-V nanowhiskers on epitaxially grown group IV nanowires. They have also demonstrated this for single crystalline GaAs whiskers, a direct band gap semiconductor with high electron mobility predestined for nanophotonics, grown on Si nanowires forming hierarchical star-like structures with a six-fold symmetry. The hetero-epitaxial growth and the good crystallinity of the Si nanowires and wurtzite-type GaAs whiskers have been confirmed by experiments.
Gold Nanodot whisker
A group of researchers have nanoengineered a structure comprising an array of more than about 1000 nanowhiskers on a substrate in a predetermined spatial configuration. It can be used as a photonic band gap array wherein each nanowhisker is located within a distance from a predetermined site not greater than about 20% of its distance from its nearest neighbour, according to an U.S. patent application.
To produce the array, an array of masses of a catalytic material are positioned on the surface, heat is applied and materials in gaseous form are introduced so as to create a catalytic seed particle from each mass, and to grow, from the catalytic seed particle, epitaxially, a nanowhisker of a predetermined material, and wherein each mass upon melting, retains approximately the same interface with the substrate surface such that forces causing the mass to migrate across said surface are less than a holding force across a wetted interface on the substrate surface.
A nano imprint lithography (NIL) process produces the required nanostructure formations. The length of the nanowhiskers may be as long as required, such as more than 1 micrometer that permits nanostructures of arbitrary depth to be formed.
Gold dots of approximately 125 nm diameter and 45 nm thickness can be seen on the substrate surface Although the growth of nanowhiskers catalyzed by the presence of a catalytic particle at the tip of the growing whiskerAtoms that are added to the tip of the whisker as it grows diffuse through the body of a solid catalytic particle or diffuse along the surface of the solid catalytic particle to the growing tip of the whisker at the growing temperature. The nanowhiskers can also be used in a light emitting diode (LED).
Iron oxide nanowhiskers with dimensions have been synthesized by selectively heating an iron oleate complex. Such nanostructures resulted from the difference in the ligand coordination microenvironments of the Fe(III) oleate complex. A ligand-directed growth mechanism is proposed to rationalize the growth process of shape-controlled nanostructures for the formation of the nanowhiskers.
C60 nanowhiskers
C60 nanowhiskers can be formed by the liquid-liquid interfacial precipitation technique which is a low-cost means of fabricating nano-structured fibres. C60 nanowhiskers can be used as active or passive elements in a number of possible applications in electronic devices with switching or sensing capabilities, low-cost, robust millimeter-wave power detectors.
Nanotube whiskers
Researchers at Massachusetts Institute of Technology in Cambridge have developed a chemical process in which carbon fibers, heated to 750° C, sprout nanotube whiskers. They then wove those stubbly fibers into a fabric, which they injected with epoxy. The nanotubes tied the layers together and created a Velcro-like effect.
Silicon nanowhiskers
When a wafer of silicon is slowly heated under high vacuum conditions, the structure of the silicon rearranges itself to form tiny little pillars of silicon of around 10nm high and self-assemble all over the surface so that one square cm might have four billion nanowhiskers. Since the tips of the nanowhiskers are very sharp, it only takes a small field to induce the whiskers of very high density. This makes them suitable for using in low field electron emitters of small and light size suitable for use in portable devices like computer displays and widescreen televisions.
Making silicon nanowhiskers
Nanowhiskers are fabricated using GNS process as follows.The Si(100) substrate (either p-type or n-type) is cleaned to remove any surface dust or dirt but the native oxide layer is not removed, so this stage is very simple and quick. In some cases ions are implanted into the surface and the substrate is inserted into a high vacuum chamber and heated using a raster scanned electron beam that scans over the substrate at high speed, heating it in a homogeneous way. The sample is slowly raised to a peak temperature of 900- 1100C and held for a few seconds and then cooled again. The substrate is removed from the vacuum at room temperature to get nanowhiskers covered over it.
Nanowhiskers formation
Nanowhisker formation occurs in a two-stage process. Firstly, decomposition of the native oxide layer occurs. Voids form in the oxide film exposing clear silicon underneath. Silicon from the voids reacts with the oxide layer and the voids grow laterally until they coalesce. This causes a roughening of the surface and an uneven surface potential energy. After complete oxide adsorption Si species begin to migrate across the surface to kinetically favoured sites or nucleating islands. Island number and size grows as the annealing continues resulting in the growth of crystalline pillars.
Sic whisker powder
Sic whisker powder are available at a purity of 99%, diameter 1-2.5micron, L/D>=20 and in cubic crystal figure.Sic whisker powder has the good chemistry stability, low heated expansion, and high efficiency of heat conductivity, electrical resistance compared with metal being in the opposite direction and very hard. Sic resists heat, grinding and crushing, especially in resisting hot shock wave, corrosion and radiation. It is used for the fuselage cover of shuttle space craft, ceramics cutting tools, measurement tools and mould, for functional ceramics, bullet-proof ceramics and piezoelectric ceramics, ceramic bearings, far-infrared ray generator, spray nozzles, radiant tubes and combustors on machine.
ZnO nanowhiskers
Researchers report that vvertically aligned ZnO nanowhiskers can be grown on Si substrates spin-coated with ZnO nanoparticles by metal organic chemical vapor deposition (MOCVD) using Me2Zn•tmeda and a mixture of O2 and Ar gases. The ZnO nanowhiskers grown are single crystals with a growth rate of 3 μm h−1.
Blanket-like assembled ZnO nanowhiskers were fabricated using a freestanding ZnO nanoparticle layer by an aqueous solution deposition. Thermal treatment of the zinc acetate dihydrate layer resulted in the formation and delamination of the ZnO nanoparticle layer on the glass substrate. The growth habits of ZnO crystals resulted in the growth of ZnO nanowhiskers preferentially orientated along the direction of the c-axis on the whole surface of the freestanding ZnO nanoparticle layer by heterogeneorous nucleation and growth. The hierarchical-structured blanket-like ZnO nanowhisker assemblies can be utilized for dye-sensitive solar cells and gas sensors because of their high surface-to-volume ratio.
Single crystalline GaAs whiskers
Researchers have carried out under carefully selected conditions the hetero-epitaxial growth of branched III-V nanowhiskers on epitaxially grown group IV nanowires. They have also demonstrated this for single crystalline GaAs whiskers, a direct band gap semiconductor with high electron mobility predestined for nanophotonics, grown on Si nanowires forming hierarchical star-like structures with a six-fold symmetry. The hetero-epitaxial growth and the good crystallinity of the Si nanowires and wurtzite-type GaAs whiskers have been confirmed by experiments.
Gold Nanodot whisker
A group of researchers have nanoengineered a structure comprising an array of more than about 1000 nanowhiskers on a substrate in a predetermined spatial configuration. It can be used as a photonic band gap array wherein each nanowhisker is located within a distance from a predetermined site not greater than about 20% of its distance from its nearest neighbour, according to an U.S. patent application.
To produce the array, an array of masses of a catalytic material are positioned on the surface, heat is applied and materials in gaseous form are introduced so as to create a catalytic seed particle from each mass, and to grow, from the catalytic seed particle, epitaxially, a nanowhisker of a predetermined material, and wherein each mass upon melting, retains approximately the same interface with the substrate surface such that forces causing the mass to migrate across said surface are less than a holding force across a wetted interface on the substrate surface.
A nano imprint lithography (NIL) process produces the required nanostructure formations. The length of the nanowhiskers may be as long as required, such as more than 1 micrometer that permits nanostructures of arbitrary depth to be formed.
Gold dots of approximately 125 nm diameter and 45 nm thickness can be seen on the substrate surface Although the growth of nanowhiskers catalyzed by the presence of a catalytic particle at the tip of the growing whiskerAtoms that are added to the tip of the whisker as it grows diffuse through the body of a solid catalytic particle or diffuse along the surface of the solid catalytic particle to the growing tip of the whisker at the growing temperature. The nanowhiskers can also be used in a light emitting diode (LED).
2/13/11
Carbon Nanotubes (CNTs), graphene and their compounds exhibit extraordinary electrical properties for organic materials.Applications
They have a huge potential in electrical and electronic applications such as photovoltaics, sensors, semiconductor devices, displays, conductors, smart textiles and energy conversion devices such as fuel cells and batteries.
Opportunities for CNT
Depending on their chemical structure, carbon nanotubes (CNTs) can be used as an alternative to organic or inorganic semiconductors as well as conductors, but the cost is currently the greatest restraint. Challenges are material purity, device fabrication, and the need for other device materials such as suitable dielectrics. However, the opportunity is large, given the high performance, flexibility, transparency and printability. The cost will rapidly fall as new, cheaper mass production processes are established. In electronics, other than electromagnetic shielding, one of the first large applications for CNTs will be conductors.
Advantages of CNT
In addition to their high conductance, they can be transparent, flexible and even stretchable making them suitable for displays, replacing ITO; touch screens, photovoltaics and display bus bars and beyond. It has higher mobilities which are several magnitudes higher than silicon, meaning that fast switching transistors can be fabricated. CNTs can be solution processed making it suitable for printing over large areas thus reducing the cost of manufacturing. As super capacitors, it bridges the gap between batteries and capacitors, leveraging the energy density of batteries with the power density of capacitors and transistors
CNT material availability
A number of companies are already selling CNTs with metallic and semi conducting properties grown by several techniques in a commercial scale but mostly as raw material and in limited quantities. However, printable CNT inks are beginning to hit the market.
Challenges
Presently purifying the raw material without significantly degrading the quality is difficult in the fabrication of thin carbon nanotube films because there is relatively poor quality of the nanotube starting material, which mostly shows a low crystallinity, low purity and high bundling. There is difficulty in getting good dispersions in solution and to remove the deployed surfactants from the deposited films. However, the selective and uniform production of CNTs with specific diameter, length and electrical properties is yet to be achieved in commercial scale.
Sales
More than one hundred companies and academic institutions are working on carbon nanotubes, graphene and their compounds, with North America focusing more on single wall CNTs, with Japan on top and China second in the production of multi wall CNTS.
Graphene
Graphene is a cheap organic material having good conductivity and hence used in some applications as a significantly cheaper printed conductor compared to silver ink. It is used to make transistors that show extremely good performance.
Graphene is a one-atom-thick planar sheet of carbon atoms that are densely packed in a honeycomb crystal lattice. It can be thought of as a network of carbon atoms and their bonds. It can also be considered an infinitely large aromatic molecule, the limiting case of the family of flat polycyclic aromatic hydrocarbons. Graphene is the basic structural element of several carbon allotropes, including graphite, carbon nanotubes, and other fullerenes.
Making graphene
Researchers made use of spun carbon-rich materials such as plexiglass onto a nickel or copper substrate to make graphene. When exposed to hydrogen and argon gas, the metal acted as a catalyst, and the material reduced to pure carbon, producing a single layer of grapheme.
Researchers of Rice University have used ordinary table sugar to process sheets of graphene. The breakthrough in graphene manufacturing is notable not only for its use of sugar, but also because it resulted in a common, non-toxic material that can be used at low temperature.
Applications
Useful for applications such as touchscreens, liquid crystal displays, organic photovoltaic cells, organic light-emitting diodes, component of integrated circuits, graphene nanoribbons for making ballistic transistors, conductive plates of ultracapacitors and for a new technique for rapid DNA sequencing
2/13/11 0
2/10/11
Barium titanate (BTO) is used as high-k dielectric phase in multi-layer ceramic capacitors (MLCC). A report prepared by Sandia National Laboratories lists three different syntheses for BTO nanoparticles.
The first synthesis is using Lanthanum-Doped Lead Zirconium Titanate (PLZT) developed at Sandia. In the reaction, metal salts are dissolved in a solution of nitric acid and water. After stirring overnight, titanium isopropoxide (Ti(OPr)4) and a solution of polyvinyl alcohol (PVA) in water are added. Finally, the acidic aqueous solution is boiled off, decreasing the solubility of the dissolved metals and leading to particle formation. The PVA forms a semi-dilute solution which limits the final particle size.
Barium nitrate
Barium nitrate
To synthesize BTO, barium nitrate was the only metal salt required. The synthesis was attempted both with equal moles of barium and titanium and a 20% excess of barium to aid final BTO formation. At room temperature, the product of all reactions was amorphous. After a post anneal of 700 °C a mixed phase product was formed. Post-annealing at 1000 °C was required to fully convert the particles synthesized via this method to crystalline BTO.
Barium acetate
Barium acetate
The second synthesis is by using barium acetate and titanium tert-butoxide as precursors. A mixture of ethylenediamine (EDA) and ethanolamine (MEA) were used as the solvent. These solvents have a basic pH and can catalyze room temperature formation of crystalline BTO. The amine functionality of these solvents also allows them to bind to the BTO surface and act as ligands. Size of the particles can be controlled by varying the EDA:MEA ratio. In addition to repeating the EDA:MEA ratio of 1:1 as in the literature, the reaction time of the 1:1 ratio sample was increased to 96 hrs. (the longest reaction time reported in the literature was 48 hrs.), and larger particles were produced as desired.
Barium hydroxide hydrate
Barium hydroxide hydrate
The third synthesis is by using barium hydroxide hydrate (Ba(OH)2•8H2O) as a reagent along with titanium isopropoxide. The entire reaction was performed in a solvent of isopropanol at a temperature of 80 °C. Although this is higher than room temperature it is still a low enough reaction temperature such that mass production of cheap particles would not be precluded.
Following the procedure described in the literature, the particles were synthesized without the addition of any water. However, this resulted in predominantly amorphous particles. Yoon and coauthors reported that the water molecules available from the Ba(OH)2•8H2O provided enough water for the reaction between the barium ions and titanium isopropoxide to move forward.
When the reaction was repeated using 6 mol of water and this time the reaction produced cubic BTO nanoparticles.
When the reaction was repeated using 6 mol of water and this time the reaction produced cubic BTO nanoparticles.
2/10/11 0
Silver has been recognized as one of the most efficient germicides known and nanosilver can be used efficiently as an antimicrobial in medicines, filters, clothing and personal hygiene products. Using nanosilver plenty of personal and house hold articles have come into the market from China, Taiwan, Korea and other countries.Nano silver fabric softener
A fragrance capsule fabric softener is built in that give fragrance relaxation with aroma. The aroma scent inside the capsules comes up whenever there is movement, makes the fragrance to last longer and subtle aroma of perfume relieves stress. Coats each and every yarn of the fabric with softening property, removes static, reduces residual laundry detergent , removes wrinkles, makes ironing easier and it gives better result when used on innerwear.
Inflatable boots keeper
Nano silver boots keeper is an antibiotic inflatable boots keeper, Inflatable balloon to keep boots straight and clean. Nano silver is coated on surface for antibiotic and deodorizing function.
Nano silver acupuncture needle
This medical equipment uses strong sterilizing effect of nano silver against disease-causing bacteria. This is because nanosilver (Ag+) has exceptional germicidal power to make numerous vesicles to easily take in oxygen and decompose bacteria. These oxygen atoms eventually oxidize and remove the harmful bacteria. Nano silver block the necessary hydrogen supply needed for virus metabolism. These chemical compounds kill virus without having harmful effect to human beings.This acupuncture silver needle is plated with nanosilver on its body and handle as well as its case in order to ensure its maximum sanitation.
Nano Silver Tub Cover
This exhibits new qualities like antibacterial, sterilization, odor removing and block electron wave etc.
NANO MAGNETIC QUILT
This quilted cloth has magnetic quilt which is light and well-ventilated, made of wool to keep warm in winter and cool in summer. But can be used in all seasons. It contains magnet and nano material to help activation of blood, physical alkalinization and antibacterial effect. Negative ion radiated from Nano material is effective on air clearing. Magnets are arranged to fit human body to revitalize ion-activity of CA, Na, K in the blood, which helps the removal of waste materials in blood vessel, increase of oxygen in blood.this is recommended for chronic fatigue, backache and headache.
Nano-Silver Foam Condom
A Chinese company called Blue Cross Bio-Medical is offering a foam condom for women made with silver “nanotech” particles. The female spray-on condom comes in a can with a plastic applicator. After the foam spray is squirted into the vagina it creates a physical membrane preventing conception and protecting against infection.
Nano Silver Beauty Soap
This is a China product Nano Silver ingredient contained in the soap sterilizes bacteria in the skin while washing.
Nano Silver Military Socks
Military socks have more complex requirements and all kinds of military socks and made out of wool / cotten / arcylic / nylon.
Nano Silver Milk Bag
This is freezer safe, pre-sterilized, keep even breast milk fresher longer, antibacterial, antifungal, and deodorizing effects.
Other products are: nano raincoat, Nano Heel care, Nano Blackhead Care, nano mask, Nano Silver Skin Care Line, Nano Silver Hand Cleaner, Nano Wood Plastic Composites material, easy-clean nano coatings, Anti-Ageing Cream, nano-silver fiber clothing, Nano-Silver Photocatalyst Bulb, Nano Silver Sanitary Napkin, Nanosilver Toothpaster, Nanosilver-Bicycle-Clothing, Nano Silver Sublingual Drops, Nano Silver Toothpaste , Nano Silver ink, Nano Silver Filter, Nano Silver Scalp Shampoo , Anti-odor Nanosilver Bicycle and a lot more.
2/9/11
Invisible fluorescent security inks have been developed using single wall carbon nanotubes by researchers of Rice University. These inks contain multiple levels of information. The shapes and or words contain one level of information and CNT marker compositions within the inks are contained in the second levels of spectral information.
Nanoinks
Such invisible inks have found wide applications in business and commerce as a means of protection against fraud, counterfeiting, and theft. These inks are invisible when printed but can be made visible through various methods to decode the written information . These inks are used to prove the authenticity of document which is commercially valuable such as stock certificates, bearer bonds, checks, lottery tickets, vouchers and as security tags to protect against the misuse of personal identification documents. use of this ink can protect documents such as social security cards, passports, visas, identification cards, credit/debit cards, automobile licenses, and vital business and health records.
Decoding mechanism
When monochromatic light of specific wavelength is made to fall on the inked surface, the letters printed with carbon nanotube ink are seen to fluoresce, emitting radiation in the NIR. This emission can be detected using a camera with suitable a detection range when exposed to multiple video frames of glowing ink made of carbon nanotubes that would otherwise be invisible. These inks after printing are colorless and transparent making them undetectable under normal light conditions but are made visible under UV light. Though conventional fluorescent inks are invisible under normal light, these inks can usually be seen when illuminated by a UV or other suitable wavelengths.
Method of working
Researchers have used carbon nanotubes as the improved highly-specific security tags, as nanotubes can be grown in a variety of size with characteristic absorption and emission wavelengths. For example, an aqueous suspension of single-walled carbon nanotubes can be applied to paper or cloth to make invisible nanotag, but fluoresces when illuminated under a specific wavelength in the near-IR using appropriate InGaAs camera equipment.
Nanotag
Spectral filtering can distinguish different nanotube species in the tag, because each will show distinct absorption and emission wavelengths. When partially or fully structure-separated nanotube samples are used, the corresponding tags will have distinct wavelengths of excitation and emission. Other fluorescent inks do not offer a variety of wavelength-specific forms that can provide this added security feature. Also, there is virtually no background emission in the near-IR, thus only tiny quantities of nanotubes are required for marking.
This discovery will lead to nanoelectronics and biomedical contrast agents for non-invasive imaging of particular types of cells. Nanotube tags, comprised of nanotubes of different diameters, could selectively inscribe different denominations of currency. Nanotube tags might also be used as “spectral bar codes” for non-contact identification of items such as clothing.
2/9/11 0
2/8/11
Quantum dots are often referred to as artificial atoms. Nanoscale materials such as semiconductor quantum dots (SQDs) have electronic and optical properties between those of much larger macro and micro scale bulk semiconductor crystals, and much smaller atoms and molecules. Some of the fundamental atom-like properties of optically active quantum dots, such as photon ant bunching and presence of absorption/emission lines predominantly broadened by radiative recombination, have already been confirmed experimentally. In contrast to atoms and electrically-defined quantum dots, optically active quantum dots suffer from spatial and spectral in homogeneity.There is considerable advancement in quantum dot forming technology but still there seems to be some problems of application of a quantum dot structure to semiconductor devices. One of them is a low efficiency of injecting carriers in quantum dots and the other is phonon bottleneck phenomenon which lowers the efficiency of injecting carriers to the ground level.
Phonon bottleneck
In a quantum dot, the electron inter-sub-level separation may not match the phonon spectrum. This could reduce or even suppress the electron relaxation via the emission of phonon(s) severely This is the "phonon bottleneck" effect. It could keep the electron gasses in the conduction and intermediate bands well separated.
The phonon bottleneck effect reduces the electron relaxation and keeps the electron gasses in the conduction and intermediate bands well separated. Phonon bottleneck effect makes also the radiative recombination between the conduction and the intermediate bands potentially dominant. The recombination between electrons and holes confined within the dots is predominantly radiative because of their high wave function overlap integrals. In the same way, photon absorption is also strong because of the great value of the overlap integrals involved.
The phonon bottleneck effect, or slowed relaxation of electrons through phonon emission in quantum dots is detrimental to their application as optical devices because it degrades the threshold current and the external quantum efficiency.
2/8/11 0
Researchers in Moldova have fabricated nanometre-thin membranes of gallium nitride for the first time and investigated their nanostructure using electron microscopy.Uses of GaN
GaN is a large-bandgap semiconductor material which is biocompatible, piezoelectric and resistant to ionizing radiation. It is widely used in electronics applications such as high-temperature, high-power electronics, optoelectronics for light-emitting diodes, lasers and spintronics devices.
Etching GaN
Researchers have now developed a technique that involves etching away high-quality crystalline material from bulk GaN epilayers to leave behind only the dislocation networks and a thin film to which the dislocations remain attached. A modified version of the surface charge lithography (SCL) technique has been recently developed for pre-treating a semiconductor surface using a low-energy ion beam to induce trapped negative charges that then effectively shield the material against subsequent photoelectrochemical (PEC) etching. For example, low-fluence Ar ions with energies as low as 0.4 keV can be applied to the GaN surface to do just this. The material remains transparent to ultraviolet light, however, so it can still be deeply etched.
GaN nano-roof
Because threading dislocations survive PEC etching due to their negative charge, etching in potassium hydroxide can create an ultra thin film membrane of GaN that resembles a "nano-roof" to which the dislocations are attached.
Nanoball
Researchers say that each dislocation has a "root" shaped like a nanoball that has pronounced features such as clustering along definite lines and loops forming mosaic structures.
Emission
The researchers also found that the dislocation networks emit mainly yellow light, while the GaN nano-roof emits both UV and yellow. The prevailing yellow part is probably related to point defects trapping the negative charge that shields the material against PEC etching.
Applications of GaN membranes
Making nanometre-thin GaN membranes transparent to both electrons and UV-light have good electrical conductivity. This fabricating technique of thin gallium nitride membranes could help better to explore two-dimensional GaN-based structures predicted to be ferromagnetic with defect-induced half-metallic configurations, particularly important for spintronics applications.
Treating HIV
Researchers at North Carolina State University claim that gold nanoparticles can be used to restore a failed HIV drug called TAK779, found as a useful therapy in the early nineties, but could not administer due to its severe side effects.
The reason
The ammonium salt present in that drug has been a main cause of harmful side effects, but could not reducing it as it would make the drug useless against HIV by disabling the resulting molecule to bind to the virus tightly. But by using gold nanoparticles the efficacy of the drug has been found to improve.
Gold nanoparticles
The researchers claim that they have found the drug-gold nanoparticle combination to be effective enough to prevent HIV from infecting lab-cultured white blood cells. They demonstrated that when each nanoparticle was equipped with nearly 12 drug molecules, the drug worked as effectively against HIV like the original drug without side effects. When a small passive molecule was conjugated with gold nanoparticle it becomes a good inhibitor of HIV. Researchers claim that a virus-killing drug attached with antiviral drug and a glucose molecule to the nanoparticles could be transported across the blood-brain barrier which has not been possible before.
Researchers at the Nano/Bio Interface Center at the University of Pennsylvania have discovered a method of producing power by exposing sunlight or any shining light on gold nanoparticles. The discovery can lead to development of self-powering molecular circuits to super-efficient data storage.Mechanism
To generate current the researchers first packed a bunch of light-sensitive gold nanoparticles together on a glass substrate and then exposed them to optical radiation (light). This knocks conductive electrons free from the gold particles, which run along the surface to create surface plasmons, which in turn induce an electrical current across the molecules.
Output
The amount of electricity generated is low, but by optimizing size, shape and orientation of the nanoparticles, a strong current can be created to run nano-sized circuits using sunlight, turn optical radiation into electrical current that could lead to self-powering molecular circuits and efficient data storage. Light-sensitive gold nanoparticles are placed on a glass substrate very closely and when stimulated, conductive electrons with optical radiation ride the surface of the gold nanoparticles, creating so-called "surface plasmons" that induce electrical current across molecules. Under these conditions, surface plasmons were found to increase the efficiency of current production by a factor of four to 20. The size, shape and separation of the array of golden nanoparticles can be customized resulting high electrical output of even upto one watt.
2/7/11
Here is a brief list of household items which utilizes the beneficial effects of nanosilver as claimed by the manufacturers/suppliers.
Fruit Nano Silver Chopping/Cutting Board (Hana Living Co., Ltd.)
Nano Silver ensures 99.9% sterilization of raw material, durability and hygiene, not harmful to the human body. The board has superior elasticity prevents abrasion from a sword cut. Available in various sizes and made of transparent material in siver or as mini. It is a deodorization and sterilization by natural sterilizer phytoncide and is easy to cut fruits or small food, it can withstand 140 deg.C
Nano Silver Ice pack (Balloonstix Korea Co., Ltd., Beijing Yushunfeng Trading Co.,Ltd.)
It is a sports and recreational equipment. This ice pack that has antibiotic function with nano silver coating and it is effective in restraining from propagation of germs, sterilizing and bad odor, and keeping proper temperature in best condition. Use: Cold transportation, Cold storage and cold massage.
Nano Silver(Ag+) Bristles (SANG SHIN INDUSTRIAL CO., LTD.)
This hair combs or brushes are produced using nano silver technology. These high-quality brush bristles are produced by mixing and processing Nylon 66 raw materials and anti-bacterial nano silver materials. The Nano Silver Bushes help in maintain healthy hair and protect the skin when used as a hair dryer for blow-dry styling, releasing anions that are beneficial, and prevent hair from being damaged and being split.
NANO HEALTHCORE PILLOW (S. H. Medical Co.,ltd)
The nano healthcore pillow is made to accommodate height to human body, has finger pressure effect with great ventilation. Magnetic effect helps to activate blood circulation, radiate negative ion in great quantities and gives anti-bacteria effect. This pillow blocks harmful underground water wave using Cu plate, gives excellent remedy for spine Inner structure.
NANO HEALTH POWER MAT (S. H. MEDICAL CO., LTD)
This belongs to rugs and mats category. Nano health power mat provides superior far-infrared ray heating effect, gives natural negative ion and magnetic effect, prevent harmful Dioxin from radiating, blocks harmful underground water wave using Cu plate, blocks harmful electronic wave using non-magnetic heat wire.
see: http://www.gobizkorea.com/blog/ProductView.do?blogid=balloonstix&id=921268
Fruit Nano Silver Chopping/Cutting Board (Hana Living Co., Ltd.)
Nano Silver ensures 99.9% sterilization of raw material, durability and hygiene, not harmful to the human body. The board has superior elasticity prevents abrasion from a sword cut. Available in various sizes and made of transparent material in siver or as mini. It is a deodorization and sterilization by natural sterilizer phytoncide and is easy to cut fruits or small food, it can withstand 140 deg.C
Nano Silver Ice pack (Balloonstix Korea Co., Ltd., Beijing Yushunfeng Trading Co.,Ltd.)
It is a sports and recreational equipment. This ice pack that has antibiotic function with nano silver coating and it is effective in restraining from propagation of germs, sterilizing and bad odor, and keeping proper temperature in best condition. Use: Cold transportation, Cold storage and cold massage.
Nano Silver(Ag+) Bristles (SANG SHIN INDUSTRIAL CO., LTD.)
This hair combs or brushes are produced using nano silver technology. These high-quality brush bristles are produced by mixing and processing Nylon 66 raw materials and anti-bacterial nano silver materials. The Nano Silver Bushes help in maintain healthy hair and protect the skin when used as a hair dryer for blow-dry styling, releasing anions that are beneficial, and prevent hair from being damaged and being split.
NANO HEALTHCORE PILLOW (S. H. Medical Co.,ltd)
The nano healthcore pillow is made to accommodate height to human body, has finger pressure effect with great ventilation. Magnetic effect helps to activate blood circulation, radiate negative ion in great quantities and gives anti-bacteria effect. This pillow blocks harmful underground water wave using Cu plate, gives excellent remedy for spine Inner structure.
NANO HEALTH POWER MAT (S. H. MEDICAL CO., LTD)
This belongs to rugs and mats category. Nano health power mat provides superior far-infrared ray heating effect, gives natural negative ion and magnetic effect, prevent harmful Dioxin from radiating, blocks harmful underground water wave using Cu plate, blocks harmful electronic wave using non-magnetic heat wire.
see: http://www.gobizkorea.com/blog/ProductView.do?blogid=balloonstix&id=921268
2/7/11 0
2/6/11
Synthesis of nanogoldTo synthesize nanogold, sodium citrate solution is added to a gold chloride solution and the mixture is heated up causing the two compounds to dissociate. Upon cooling the mixture, gold atoms, sodium chloride and negatively charged citrate ions are produced. Since the gold atoms are not charged, they tend to clump or cluster together, negatively charged citrates surround the gold particles, “caging” them in and dividing the gold atoms into smaller groups. The amount of citrate in the solution determines the size of the gold clusters. More citrate results in smaller clusters of gold, less citrate in larger clusters.
Commercial nano gold solution contains nano sized pure gold having a size of 5-20 nm and the solution is based on pure water, with solution content in ppm levels.
NanoGold Inks
Nanogold conductive inks have nanocrystals with small particle size less than 10 nm with low processing temperature (less than 200°C), which is largely desired for printing electronic devices on plastics or papers. Nanogold ink contains 10%-12% Au, available in a variety of surface chemistry for different solvent dispersions and applications with low resistivity and low process temperature.
2/6/11 0
Quantum dots are tiny structures made of semiconductor materials of size 15 nm and when a photon of light knocks an electron into the conduction band an electron/hole pair is created and the pair cannot escape from the dot. This confinement means that the wavelengths of the wave functions of both the electron and the hole are forced to be significantly smaller and more on top of each other inside a quantum dot than they would be in ordinary semiconductor material.Mechanism of blinking
When electron/hole pairs recombine energy is released as light. The energy released in this merger kicks the second electron out of the quantum dot onto the dots surface where it is trapped. The trapped electron creates a huge electric field across the dot which prevents it from emitting photons until the trapped electron can finally tunnel back into the dot and recombine with its hole.
When continuously illuminated by a laser, quantum dots blink on and off randomly from a microsecond to several minutes. Blinking is caused by an electron that, upon photo excitation, escapes the core and becomes trapped in the shell, forming a charged QD. At that point, non-radiative relaxation is favored and, for an instant, emission ceases.
Blinking quantum dots have high brightness, well-defined monochromaticity and superior photo stability. Blinking quantum dots randomly blink even under steady irradiation, a peculiarity that has prevented wider use.
Uses of quantum dots
Quantum dots are being intensively investigated for applications such as light-emitting diodes, solid-state lighting, lasers, solar cells, fluorescent labels for biological imaging and as dyes capable of emitting a wider range of colors with greater stability.
Nonblinking quantum dots
Researchers of the University of Rochester, Cornell University, Kodak Eastman and the Naval Research Laboratory in the USA, have synthesized a QD which emits a constant stream of light and are "nonblinking," in that they emit light steadily. The new quantum dots have multiple peaks in their emission spectra which mean that emission spectra of different quantum dots overlap and remain in excited state before emitting a photon in much shorter than that of traditional CdSe nanocrystals.
Unlike in a typical QD, the core (CdZnSe) and the shell (ZnSe) fade into each other, so there is no abrupt boundary between the two regions. The potential energy surface declines steadily towards the center of the QD. In this way, the non-radiative mechanism becomes highly unfavorable, even when a charged QD is formed. Irradiation remains steady for hours.
2/5/11
Nano silver particles for printing
Nano silver particles are uniformly dispersed in polar or non-polar solvent as high solid content/high viscosity ink for new and conventional printing applications such as silk screen, gravure, flexography, micro contact printing and nanoimprinting. Printed fine electrodes offer bulk silver conductivity at flexible curing conditions. Nano silver particle offers excellent fine patterning with superior process capability having a wide range of curing temperature for plastics and glass. Conductivity is as low as bulk silver offering high conductivity even in microscale patterned electrode.
Applications
Nano silver particle is suitable for conventional and cutting-edge printing technologies like silk-screen, gravure, off-set and micro contact printing. Also it is used in the manufacture of plasma Display Panel electrodes, flexible printed circuit board, radio frequency identification, electromagnetic interference, solar cell, other flexible display and printed electronics.
Commercial products (Metalon® Conductive Inks)
Inkjet nano silver ink
Inkjet nano silver ink is mainly composed of nanoparticles dispersed in continuous solvent phase. With excellent conductivity at low sintering temperature, the ink can be printed on a variety of substrates such as paper, silicon, PI, PET and so on. The size of nanosilver particles ink is less than 10nm with homogeneous distribution. Hardly cause any clogging in the print head. High conductivity can be achieved with sintering temperature at 140°C for 5 to 10min.
Inkjet silver in water
This is an inkjettable, aqueous, nano-silver ink formulated for a broader variety of porous and non-porous substrates, such as plastic films, papers, glass, quartz, and even silicon. Additional curing with thermal or Pulse Forge equipment will further increase conductivity. This ink is suitable for piezo-style inkjet heads.
Screen-print silver inks in water is designed to produce conductive traces on substrates such as PET, glass, polyimide, and silicon.
Nano silver spray deposition in solvent makes up a stretchable, nano-silver, solvent based ink that retains conductivity with up to 100% elongation. This ink was formulated for polyethylene film, and is also compatible with other plastic substrates.
2/5/11 0
2/4/11
Silicon inks are used for printed electronics. Silicon ink is comprised of silicon nano-particles dispersed in an environmentally friendly blend of chemicals and formulated to be compatible with low-cost industry standard screen printers.NanoGram has developed atechniques to make such inks. The company's patented technology involves injecting silicon compounds in a gaseous phase (such as silane gas) into an optically modified laser beam field, whereby the huge amount of energy absorbed by the precursor breaks the compounds into its constituent materials, such as silicon metal and hydrogen which reform in the reaction zone to form pure silicon nano particles and hydrogen gas. The silicon nano particles are immediately and rapidly cooled as they exit the reaction zone to freeze the particle size and crystallinity and are collected in a filter.further the silicon particles are doping during the reaction in highly controllable doping levels. Once collected, the particles are used to formulate silicon inks.Courtesy: NanoGram, http://www.nanogram.com/
The silicon is too expensive, fragile, and slow to market. To replce this a technology in the form of printable electronics and electronic components using metallic inks is emerging. Using such inks and conventional printing techniques circuits can be printed on flexible substrates and every print can be made unique by using digital printing techniques. metallic inks can also be used to print transistors, displays, interconnects, sensors and even sound actuators.
Applications
Printed circuit technology will be used in creating flat panel displays for TVs, printable electronic backplanes for TFT (Thin-Film Transistors), flexible circuits for OLED displays, and RFID (Radio- Frequency Identification) antennas. It will be used for short run electronics, disposable devices (smart cards, disposable displays, E-books), and electronic components (antennas, sensors etc.).
Advantages
Cost of printing is low because the equipment used to print metallic inks is much less expensive, cumbersome, and hazardous compared to the conventional chemical etching process. Smaller amount of material is used and so lines for printed circuits will be thinner (0.1 - 2.0 microns compared to ~10 microns in traditional techniques) and narrower (10 - 50 microns). This will significantly save on material for printed circuits. The printed electronic industry requires inks of high quality, inexpensive, low temperature sintering nanosilver inks in large quantities and hence large scale production of printable electronics will result in a cost effective process. Silver nanoink exhibits high conductivity without any staining effect and have a quality of printed lines will be excellent.
2/4/11 0
Nano-gold and Nano-silver toothbrush
Through the use of highly advanced nano technology gold ha been added to the brush. This has an anti-bacterial effect and emits infrared rays, which are beneficial for oral care. The soft and thin brushes remove plaque from between teeth, between teeth and gums, or from small cracks, and softly massage the gums. The brushes cleanly remove fine plaque stuck on the teeth and the gums. This brush is good for those who have weak gums and cold-feeling teeth. The product is by E.Q & Tech Corp. Korea.
Cyclic Nano Silver Cleanser
Cyclic Nano Silver Cleanser
Cyclic Nano Silver Cleanser exerts an exfoliating effect on the skin, allowing new, healthy skin to shine through. Usefull for normal abd oily skin, fights acne, eliminates or diminishes age spots. It is not a soap but it is a cleansing material with a scientifically balanced blend of Nano Silver and other premium naturally occurring ingredients that promotes the cleansing experience far superior to other cleansing products. It penetrating deep into the pores, cleaning them of dirt, excess oil, bacteria, and fungi, all of which are the major contributors to skin problems. It is a neutral aqueous solution, a structure of silver particles under 10nm combined with Si02 of 10~20nm or edible gelatin, which disperses in water uniformly and stably. See: www.conair.com
Nano-silver Tourmaline Ceramic Ionic Steam Straightener
This professional high-heat steam straightener made by Conair combines ultra-high heat, 200º C steam, nano-silver, ionic and tourmaline ceramic technology for 60% longer-lasting results and 30% faster styling. Steam locks in style with moisture for extra conditioning, added shine and longer-lasting styles, gently detangles hair using retractable detangling pins adjustable for different hair lengths. It has Nano-silver technology uniting microparticles of ceramic and silver for a unique combination of benefits that creates smooth, shiny, enhanced healthy hair. See: www.conair.com
Nano-silver Tourmaline Ceramic Ionic Steam Straightener
This professional high-heat steam straightener made by Conair combines ultra-high heat, 200º C steam, nano-silver, ionic and tourmaline ceramic technology for 60% longer-lasting results and 30% faster styling. Steam locks in style with moisture for extra conditioning, added shine and longer-lasting styles, gently detangles hair using retractable detangling pins adjustable for different hair lengths. It has Nano-silver technology uniting microparticles of ceramic and silver for a unique combination of benefits that creates smooth, shiny, enhanced healthy hair. See: www.conair.com
Nano Silver Tourmaline Ceramic Rollers
The latest innovation from Infiniti by Conair uses Nano Silver Tourmaline Ceramic technology to style hair quickly, minimizing heat damage and leaving hair less frizzy and more manageable. It only takes minuets to do hair. It is simple and safe to use for any types of hair. Instant Heat rollers can create any style, this technology not only heats rollers quickly but also holds heat while they work. The features are:
Multi-sized for infinite styling
Ionic Technology for less frizz and more manageability
Instant Heat Hairsetter with 20 Flocked Rollers
Even heat for less damage
2-Minute Instant Heat Up
12 Temperature Settings
On/Off Switch with auto shutoff
Nano Silver Keyboard Skin for Laptop
Nano Silver Keyboard Skin for Laptop
It is made of Patented Nano Silver TPU, Anti Bacterial, Environmentally non-toxic material, Durable for millions of typing, Elastic and comfortable, Waterproof, Dustproof and Washable.
Nano Silver Ice pack
This is the ice pack that has antibiotic function with nano silver coating and it is effective in restraining from propagation of germs, sterilizing, deodorizing, keeping proper temperature in best condition. Used for cold transportation, cold storage and cold massage.
Nano Silver(Ag+) BristlesHair combs or brushes
It used Nano Silver technology. Produced with high-quality brush bristles for healthy hair. To accomplish this, brush bristles are made by mixing and processing Nylon 66 raw rnatei-ials and anti-bacterial Nano Silver materials. The Nano Silver Bushes help maintain healthy hair and protect the skin when used as hair dryer for blow-dry styling, releasing anions that are beneficial and prevent hair from being damaged and splitting.
See: www.conair.com/
See: www.conair.com/
2/3/11
Novel functional nanomaterials are the basis of newly emerging nanotechnologies for various device applications significantly impact diverse fields, such as nanophotonics, spintronics, catalysis, cosmetics or biomedical applications and can be tailored to achieve desired functions. Functional nanomaterials included gold, silver nanoparticles and single wall carbon nanotubes and others.
Heterojunction nanowires
High-definition metal-oxide-metal (MOM) heterojunction nanowires are made by sandwiching axially a nanoscale segment of a functional oxide between two noble-metal nanowires. These MOM nanowires have distinct advantages over all-oxide nanowires (where the entire nanowire is an oxide), in terms of the true nanoscale nature of the oxide (both radially and axially), integral high-quality electrical contacts, ease of assembly, and low losses. These MOM nanowires have been integrated into circuits with macroscopic contacts. This nanowire architecture provides a unique opportunity to study fundamental nanoscale size-effects in functional oxides, without the dominating effect of the substrate, in the context of dielectric, chemical-sensing, ferroelectric, piezoelectric, and magneto electronic properties. These nanowires could also be used as 1-D building blocks in the "bottom up" approach to multifunctional nanoelectronics.
Graphene
Graphene is a close relative of other novel arrangements of carbon atoms-nanotubes in which the sheet is rolled into a tube shape and buckminsterfullerene, the 60-atom spheres also called buckyballs. Graphene holds potential for profoundly transforming materials science, everything from computer chips and flexible displays to solar cells and lighter aircraft. One of graphene's top properties is its ability to conduct electricity. It is not a superconductor, but it loses relatively little energy to resistance compared with most materials. It could be used, for example, to make plastic conductive. It is very strong but very light in weight.
Graphene (2-D carbon sheets) possess some highly unusual electronic and quantum properties which can lead to devices such as high-frequency field-effect transistors, single-electron transistors, chemical sensors, magneto electronics, etc.
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2/2/11
Researchers of Technische University of Muenchen have succeeded in arranging rod-shaped molecules in a two-dimensional network to form small rotors spontaneously that can rotate as an assembly.Researchers have built up an extensive nano lattice by allowing cobalt atoms and rod-shaped molecules of sexiphenyl-dicarbonitrile to react with each other on a silver surface. This has resulted in a honeycomb-like lattice automatically assembled with regularity and stability.
When the researchers added further molecular building blocks, the rods spontaneously gathered, typically in groups of three, in a honeycomb cell while neighboring cells remained empty.
Researchers found that three molecules oriented themselves in such a way that the nitrogen ends each faced a phenyl-ring hydrogen atom. This triple-bladed rotor arrangement is so energetically advantageous that the molecules maintain this structure even when thermal energy is applied to rotate it.
The assembly of cell is not round, but hexagonal and hence there are two different possible positions for the rotors formed as a result of the interactions between the outer nitrogen atoms and the hydrogen atoms of the cell wall. Furthermore, the three molecules arrange in a clockwise and a counter-clockwise manner.
For example rods of sexiphenyl-dicarbonitrile can be made to spontaneously form three-bladed rotors and when thermal energy is supplied, they start rotating in their honeycomb-cage.
The discovery of such self-organizing structures hold enormous potential and this discovery can be used to build simple mechanical models to optical or electronic switching,
2/2/11 0
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