5/31/11
Researchers at Rensselaer Polytechnic Institute have discoed that graphene can substitute copper and silicon in nanoelectronics.Graphene
Graphene, a one-atom-thick sheet of carbon of which graphite is the most common material is made up of countless layers of graphene. Researchers broke apart these layers and exploited the extremely efficient conductive properties for use in nanoelectronics. The length, as well as the width, of graphene directly impacts the material’s conduction properties. In the form of a long 1-D nanoscale ribbon, graphene demonstrates unique electrical properties that include either metallic or semi conducting behavior.
Nanorectangles
When short segments of this ribbon are isolated into tiny zero-dimensional (0-D) segments called “nanorectangles,” where the width is measured in atoms, they are classified as either “armchair” or “zigzag” graphene nanoribbons. Both types of nanorectangles have unique and fascinating properties. 1-D nanoribbons were trimmed the length down to a few nanometers, so the length was only a few times greater than the width. The lengths of the resulting zero-dimensional graphene nanorectangles had clear and distinct effects on the material’s properties.
Researchers used quantum mechanical simulations and predicted that the length of graphene may be used to manipulate and tune the material’s energy gap. This is so because energy gaps determine if the graphene is metallic or semi conducting.
Interconnect material
Major computer companies are already working on alternate the materials like carbon nanotubes as carbon nanotubes are essentially made of rolled-up graphene, with a potential to replace copper as the primary material used for interconnects. But they suffer from setbacks similar to those of graphene. Generally, when graphene is synthesized, there is a mix of metallic and semiconductor materials.
Researchers developed a way to mass produce metallic graphene that could one day replace copper which is the primary interconnects material on nearly all computer chips. But when copper interconnects are made smaller, the copper’s resistance increases and its ability to conduct electricity degrades to produce heat which will affect computer chip’s speed and performance. So graphene could be a possible better successor to copper because of metallic graphene’s excellent conductivity even at room temperature at the speed of light and with little resistance. Also graphene interconnect can stay much cooler than a copper interconnect of the same size.
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5/30/11
Among the several different forms in which carbon exist, graphite is the most common form, which consists of stacked sheets of carbon with a hexagonal structure. Graphene
Graphene is a single layer of carbon packed in a hexagonal (honeycomb) lattice and its electronic structure is different from usual three-dimensional materials. Its Fermi surface is characterized by six double cones. In intrinsic (undoped) graphene the Fermi level is situated at the connection points of these cones. The electrical conductivity of intrinsic graphene is quite low, as density of states of the material is zero at the connection points of these cones.
Doping
But the Fermi level can however be changed by an electric field so that the material becomes either n-doped (with electrons) or p-doped (with holes) depending on the polarity of the applied field. Graphene can also be doped by adsorbing water or ammonia on its surface. The electrical conductivity for doped graphene is potentially quite high.
Applications
Graphene is practically transparent, maintains its 2D properties at room temperature and in the optical region it absorbs only 2.3 per cent of the light in contrast to low temperature 2D systems based on semiconductors. It is an ultimately thin, mechanically very strong, transparent and flexible conductor. Its conductivity can be modified over a large range either by chemical doping or by an electric field. The mobility of graphene is very high, which makes the material very interesting for electronic high frequency applications.Using near-industrial methods, large sheets of graphene with a width of 70 cm have been produced.
Since graphene is a transparent conductor it can be used in applications such as touch screens, light panels and solar cells, where it can replace the rather fragile and expensive Indium-Tin-Oxide (ITO). Flexible electronics and gas sensors are other potential applications. The quantum Hall effect in graphene could also possibly contribute to an even more accurate resistance standard in metrology. New types of composite materials based on graphene with great strength and low weight could also become interesting for use in satellites and aircraft.
5/30/11 0
Nanotechnology patentsNanotechnology is the technology for the creation and use of materials or devices at extremely small scales. Nanotechnology already has a tremendous impact on everyday life, it is multidisciplinary in nature contributing immensely to industry and society. Plenty of patent applications have been filed on many discoveries, The following are few important key areas obtained from published literature on which application have been filed.
• Electronics: semiconductor memories, magnetic random access memories, flat panel display devices, quantum information processing, and molecular devices
• Optoelectronics: lasers, photonic crystals, optical devices, optical waveguides
• Medicine and biotechnology: drug deliveries, molecular detection method, and high resolution
• DNA detection method, applications of TiO2 to sun screening.
• Measurements and manufacturing: matrix screening methods, scanning probe microscope, and
• polymer processing method
• Environment and energy: fuel cell electrode, non-aqueous electrolyte secondary cell, and lithium secondary cell.
• Nano materials: carbon nanotubes, organic nanotubes, nano-whisker, and oxide particles.
• self assembled nanoparticles, nanotubes, nanorings, nanowires, nanocomposites
• nanorobotic arm out of synthetic DNA
• biotech applications - molecular nanotechnology or molecular manufacturing
• nanoassemblers, nanocomputers, and nanochips along with molecular electronics
• Ultrasmall sensors, power sources, communication, navigation, and propulsion systems with very low mass, volume and power consumption
• use nanoparticles in sunscreens and cosmetics, in clothes to make them stain and wrinkle resistant, in bandage and in food additives into drinks
• Coatings, Self cleaning, anti-biofilm surfaces, anti-fire and secured coatings, thin coatings generating energy, stable nano paints, templates
• NEMS, Architectures, nano Integral Circuits etc.
• Colloids, anti-fair nanoFluids
• Nanopolymers and membranes, UV barriers
• Mechanically and temperature reinforced foils, packaging materials, nanoclays
• Hydrogen Fuel Cell & Other alternative nano approaches
• Nanocapsuled food items
• "smart" pesticides delivery, nano sensors
• Nanomotors and Nanomachines
• development of new catalysis agents, innovative fuel cells, and highly efficient solar energy conversion
5/28/11
Nanotech textilesTextiles with integrated electronics, special self-cleaning abilities, resistance to fire, protection from ultraviolet light, and a range of other features are nanotechnology applications. There is currently a huge amount of research and development being conducted across the globe from universities to global corporations to design and create the next generation textiles. Novel nanotech textiles are already being integrated into leading-edge applications for a range of industries including aerospace, automotives, construction and sportswear. They also hold significant promise for the healthcare industry in self-cleaning surfaces, smart surgical gloves, implants and prosthetics and round-the-clock patient monitors. UV-blocking textiles enhanced with zinc oxide nanoparticles and extremely strong, wear-resistant surface coatings are two approaches likely to have application in the military, aerospace and other civilian products. Examples of industries where nanotech-enhanced textiles are already seeing some application include the sporting industry, skincare, space technology and clothing and material technologies for better protection in extreme environments. Treating textiles with nanotechnology materials is a method to improve the properties of the textile, making it longer durable, have nicer colours etc. Nanotechnology can also be used to add new functionalities like energy storage and communications. Some interesting examples of nano improved textiles currently on the market are:
• Stain repellent and wrinkle-resistant threads woven in textiles
• Body warmers use Phase Change Materials (PCMs) responding to changing body temperatures
• Nanosocks treated with silver nanoparticles. The silver acts against infection and odour.
Swimming suit
The most widely recognized application t is in the shark-skin suit worn during world-record breaking Olympic swimming championship. The suit, which includes a plasma layer enhanced by nanotechnology to repel water molecules, is designed to help the swimmer glide through the water and has become a common feature of major swimming events as all competitors attempt to enhance their chances of winning.
Sporting goods
Running shoes, tennis racquets, golf balls, skin creams, and a range other sporting goods have also been enhanced by nanotechnology. As well as developing textiles to withstand extreme environments, scientists have looked to naturally existing viral nanoparticles that live in some of the harshest environments on earth, for new building blocks for nanotechnology. A garment that senses their surroundings and interacts with the wearer is an area of considerable interest. Such textile-based nanosensors could provide a personalized healthcare system, monitoring your vital signs as you run up a hill or responding to changes in the weather.
Flexible electronic circuits
Nanoribbons form the basis for the chips which are so flexible they can wrap around the edge of a microscope cover slip and so stretchable they can be twisted into a corkscrew. The researchers are focusing applications development in the healthcare industry and believe these tiny, flexible electronic sheets could one day be used to line the brain to monitor activity in patients at risk of epilepsy or be integrated into surgical gloves to monitor a patient’s vital signs during surgery.
Lifestyle applications
Perhaps surprisingly the earliest commercialized applications of nanotechnology are seen in lifestyle applications. Textile and cosmetics are among the first products to use nanomaterials. The examples of nanotechnology materials and technologies in lifestyle application is bullet proof vests. Nanotube fibers are used to make a material seventeen times tougher than the Kevlar. Future developments are to use nanotechnology to create Smart and Interactive Textiles (SMIT) that can sense electrical, thermal, chemical, magnetic, or other stimuli.
Currently however, the major part of advanced textiles is relative low tech products like photo chromic t-shirts. Nanotechnology can be used to give fabrics a wide range of properties such as being:
• Resistant to spills and stains
• Create superior temperature moderation when the wearer moves between hot and cold external temperatures
• Really permanent press and wrinkle resistance
• Able to oxide smog
• Antibacterial and antifungal
• Color fast without dyes because the color is a function of the nanoparticle.
5/28/11 0
Nanotube yarn
Carbon nanotubes can conduct both heat and electricity besides having extreme toughness. Using a sharp, pointed instrument researchers have pulled carbon nanotubes into fibers along the plane of the substrate and were twisted and wrapped around each other as they were pulled to get a very even strand.
Nanotube yarn detects blood
Chinese and U.S. researchers have developed a carbon nanotube-coated smart yarn which can conduct electricity and be woven into textiles to detect blood or to monitor health. The team combined two fibers, one natural and one created by nanotechnology, to build a new kind of smart textile. If a soldier wearing clothes made with this fabric was wounded, his mobile phone could alert a nearby patrol to save his life.
Making the fabric
To make this fabric the researchers dipped 1.5-millimeter thick cotton yarn into a solution of carbon nanotubes in water and then into a solution of a special sticky polymer in ethanol few times into both solutions and dried. By repeating the process a few times, normal cotton becomes a conductive material due to the carbon nano tubes which are conductive in nature. The yarn is that it turned black, due to the carbon. The yarn was able to conduct enough power from a battery to illuminate a light-emitting diode device. In order to put this conductivity to use antibody anti-albumins is added to the carbon nanotube solution. Anti-albumin reacts with albumin, a protein found in blood and the anti-albumin-infused smart yarn conductivity significantly increases.
Applications
The smart textiles remain pliable, soft, more sensitive and selective as well as more simple and durable than other electronic textiles. Such fabric can detect blood and be useful in several high-risk professions. An unconscious fire-fighter, ambushed soldier, or police officer in an accident, can be saved the smart fabric can send a distress signal from a communication device such as a mobile phone from the clothing to a central command post. The clothes can be designed to store energy, which will provide power to operate small electronic devices. Other applications include wearable simple, sensitive, selective and versatile biomonitoring and telemedicine sensors, which can be made using a polyelectrolyte-based coating with carbon nanotubes integrated with humidity sensing and for albumin detection. Clothing fibers coated with cylindrical, nanosize carbon molecules that contain antibodies can detect the presence of albumin, a protein common in blood. The shirt senses that its wearer is bleeding and sends a signal through the shirt’s carbon nanotubes that activates an emergency radio-frequency beacon on the soldier’s belt. This distress call can be picked up and further action taken.
Functional clothing
Scientists at Cornell have developed functional clothing that can prevent colds and flu and never needs washing, destroys harmful gases and protects the user from smog and air pollution. The two-toned gold dress and metallic denim jacket contain cotton fabrics coated with nanoparticles that give them functional qualities. The garments show electrostatically charged nanoparticles creating a protective shield around the cotton fibers in the top part of the dress, and the sleeves, hood and pockets of the jacket.
Fabrication
The fabrics were dipped in solutions containing nanoparticles and its colors depend on particle size or arrangement. The upper portion of the dress contains cotton coated with silver nanoparticles. Researcher first created positively charged cotton fibers using ammonium-and epoxy-based reactions, inducing positive ionization. The silver particles, about 10-20 nanometers across were synthesized in citric acid, which prevented nanoparticle agglomeration. Dipping the positively charged cotton into the negatively charged silver nanoparticle solution resulted in the particles clinging to the cotton fibers. Silver possesses natural antibacterial qualities that are strengthened at the nanoscale, thus giving the dress the ability to deactivate many harmful bacteria and viruses. The silver infusion also reduces the need to wash the garment, since it destroys bacteria, and the small size of the particles prevents soiling and stains. The jacket includes a hood, sleeves and pockets with soft, gray tweed cotton embedded with palladium nanoparticles, about 5-10 nanometers in length. To create the material, negatively charged palladium crystals are placed onto positively charged cotton fibers.
In the case of an anti-smog jacket cotton fiber incorporated with special nanomaterials into a jacket with the ability to oxidize smog. Such properties would be useful in case of allergies, or for protecting from harmful gases in the contaminated air.
Water repellent fabric
The G3 Technology Innovations has provided water repellency and other benefits to fabric by using a coating of tiny nanoparticles of fluorocarbons by avoiding coating textiles with large quantities of fluorocarbons. This reduction in fluorocarbons is associated with safety against various health and environmental risks. Information on product availability is at http://www.victor-innovatex.com/.
5/27/11
For semiconductors, the electrochemical deposition technique was used in 1996 for fabricating arrays of CdS NWs with lengths up to 1 mm and diameters as small as 9 nm. Researchers have reported that a group of II–IV semiconductor NW arrays (CdS, CdSe, and CdTe) can be made by dc electrochemical deposition in porous AAO. Nano wires (NW) may also be grown by electrochemical deposition methods in combination with templates such as porous anodic aluminum oxide (AAO), nano-channel glass, and porous polymer films self-organized from diblock copolymers. Process
For the growth of nano wires, the template is attached to the cathode and subsequently brought into contact with the deposition solution. The anode is placed in the deposition solution parallel to the cathode. When an electric field is applied, cations diffuse towards and get reduced at the cathode, resulting in the growth of nanowires inside the pores of the template. After pore filling, free-standing nanowires can be obtained by dissolution of the template membrane. The length of the pores, which can be tuned by the etching process, determines the length of the NWs.
Template
The most widely used templates for electrochemical deposition of NWs is AAO, which has been used for the fabrication of a wide range of NW materials including mainly metals, conductive polymers, and metal oxide materials, as well as multi segmented NWs.
Cylindrical nanowires
As a further step, the pores in the templates/membranes can be regularly arranged to have a cylindrical shape of a constant diameter. This is achieved by imprinting the aluminum surface prior to the anodization process with a lithographically prefabricated stamp to generate specific arrangements of pores and the resulting NWs have a narrow size distribution.
Self-organization
Self-organization of metal and semiconductor NWs can be made to occur by electrochemical step-edge decoration of highly-oriented pyrolytic graphite surfaces. This is a large-scale approach to fabricate supported NWs. When combined with modern nanolithography techniques, this method can be potentially extended to horizontally aligned NWs of various shapes. However, while the material produced by this technique is limited mainly to metals, a second chemical reaction of the metal NWs is needed in order to transform them into semiconductors. The key issue for semiconductor NWs fabricated by electrochemical deposition is the crystalline quality. In most cases the NWs are not epitaxially grown and hence are either amorphous or polycrystalline in structure. They consist of small crystals with an abundance of defects, which might limit their technical application, especially in optics.
5/27/11 0
5/26/11
Engineers at Brown University and in India have created a nanopatch with carbon nanofibers and a polymer to repair heart damaged after heart attack.
Problem
When there is a heart attack, a part of the heart dies. During that time, nerve cells of heart wall and those cells which keep the heart beating do not function. Heart surgeons can not even repair the affected area of the heart.
Solution
Using nanotechnology, scientists have built a scaffold-looking structure consisting of carbon nanofibers and a polymer as a patching solution. In laboratory tests, natural heart-tissue cell density on the nanoscaffold was six times greater than the control sample, while neuron density had doubled.
Tests have shown that such a synthetic nanopatch can regenerate natural heart tissue cells ¬ called cardiomyocytes as well as neurons meaning that a dead region of the heart can be brought back to life.
Process
Researchers of Brown and Indian Institute of Technology, Kanpur employed carbon nanofibers, helical-shaped tubes with diameters between 60 and 200 nanometers. The carbon nanofibers work well because they are excellent conductors of electrons, performing the kind of electrical connections the heart relies upon for keeping a steady beat. The researchers stitched the nanofibers together using a poly lactic-co-glycolic acid polymer to form a mesh about 22 millimeters long and 15 microns thick and resembling "a black Band Aid." They laid the mesh on a glass substrate to test whether cardiomyocytes would colonize the surface and grow more cells.
In tests with the 200-nanometer-diameter carbon nanofibers seeded with cardiomyocytes, five times as many heart-tissue cells colonized the surface after four hours than with a control sample consisting of the polymer only. After five days, the density of the surface was six times greater than the control sample, the researchers reported. Neuron density had also doubled after four days, they added.
The scaffold works because it is elastic and durable, and can thus expand and contract much like heart tissue. This is a great boon to millions if heart patients.
When there is a heart attack, a part of the heart dies. During that time, nerve cells of heart wall and those cells which keep the heart beating do not function. Heart surgeons can not even repair the affected area of the heart.
Solution
Using nanotechnology, scientists have built a scaffold-looking structure consisting of carbon nanofibers and a polymer as a patching solution. In laboratory tests, natural heart-tissue cell density on the nanoscaffold was six times greater than the control sample, while neuron density had doubled.
Tests have shown that such a synthetic nanopatch can regenerate natural heart tissue cells ¬ called cardiomyocytes as well as neurons meaning that a dead region of the heart can be brought back to life.
Process
Researchers of Brown and Indian Institute of Technology, Kanpur employed carbon nanofibers, helical-shaped tubes with diameters between 60 and 200 nanometers. The carbon nanofibers work well because they are excellent conductors of electrons, performing the kind of electrical connections the heart relies upon for keeping a steady beat. The researchers stitched the nanofibers together using a poly lactic-co-glycolic acid polymer to form a mesh about 22 millimeters long and 15 microns thick and resembling "a black Band Aid." They laid the mesh on a glass substrate to test whether cardiomyocytes would colonize the surface and grow more cells.
In tests with the 200-nanometer-diameter carbon nanofibers seeded with cardiomyocytes, five times as many heart-tissue cells colonized the surface after four hours than with a control sample consisting of the polymer only. After five days, the density of the surface was six times greater than the control sample, the researchers reported. Neuron density had also doubled after four days, they added.
The scaffold works because it is elastic and durable, and can thus expand and contract much like heart tissue. This is a great boon to millions if heart patients.
5/26/11 0
Fuel cellsFuel cells are the most important electrochemical tools for the direct conversion of chemical energy to electrical energy and they are secure and environment-friendly. The electrodes are very important pieces of the cells which is usually produced using costly platinum metal as anode in the electro-oxidation of methanol in fuel cells. Iranian researchers at University of Mazandaran produced an electrode with the help of carbon nanotubes, which can increase the rate of electro-oxidation of methanol in fuel cells.
Methanol fuel cell
DMFC has a polymer electrolyte and the charge carrier is the hydrogen ion (proton). The liquid methanol (CH3OH) is oxidized in the presence of water at the anode generating CO2, hydrogen ions and the electrons that travel through the external circuit as the electric output of the fuel cell.
One of the drawbacks of the DMFC is that the low-temperature oxidation of methanol to hydrogen ions and carbon dioxide requires a more active catalyst, which typically means a larger quantity of expensive platinum catalyst is required which increases cost but of course without a reforming unit.
Carbon nanotubes
Carbon nanotubes are molecular-scale tubes of graphitic carbon with outstanding properties having stiffest and strongest fibers known with remarkable electronic properties and many other unique characteristics. For these reasons they have attracted academic, industrial and commercial applications. According to the scientists, using nanotubes modified electrodes has been developed due to the unique structural ability and amazing physico-chemical properties such as high ratio of area to volume and high electrical conductivity. The production of from the carbon paste containing modified carbon nanotubes was achieved.
Production
The electrode was produced by synthesizing the carbon paste containing carbon nanotube by mixing graphite powder, paraffin oil and multi-walled carbon nanotube. Then, it is modified with poly (meta-toluidine)/triton through a voltammetric cycling method. Finally, the platinum particles are electrochemically precipitated on the polymeric film existing on the surface of the electrode in order to produce the final electrode.
The scientists claim that they have designed an electrode by using a simple and non-ionic surfactant, which is able to catalyze the oxidation of methanol at a higher current intensity.
5/25/11
1. Nanosafe, Grenoble France, Maison Minatec, 2012, Nov 13 - 15, 2012
2. Nano Health, Cairo Egypt, Cairo Marriott, Jan 15 - 16, 2012
3. Nanomaterials for Sustainable Energy, New Delhi India, Indian Institute of Technology Delhi, - EU-India workshop and school, Nov 01 - 04, 2011
4. Nano Petroleum, Gas and Petro Chemical Industries Conference, Cairo, Egypt, Cairo Marriott Hotel, Nov 13 - 14, 2011
5. Nanoscale Bioceramics in Healthcare and High Performance Ceramics, Stoke-on-Trent UK, Oct 12 - 13, 2011
6. 6th International Conference on Surfaces, Coatings and Nano-Structured Materials (NANOSMAT), Best Western Premier Hotel-Krakow, Krakow Poland, Oct 17 - 20, 2011
7. Nano and Giga Challenges in Electronics, Photonics and Renewable Energy, Moscow State University, Moscow Russia, Sept 12 - 16, 2011
8. Environmental Effects of Nanoparticles and Nanomaterials 2011, The Royal Society, London UK, Sept 19 - 19, 2011
9. The NEC MM Live UK 2011, MEMS LIve UK 2011, NANO Live UK 2011, Birmingham UK, Sept 27 - 29, 2011
10. NanoIsrael 2012, the third annual conference & exhibition, to be held in Tel Aviv on 26-27 March, 2012
11. NanoElectroCatalysis 2012 Nano-materials Electrochemistry and Catalysis, May 1, 2012 - May 4, 2012 Banff ,Alberta ,Canada, Jan 1, 2012
12. NMDC 2011 IEEE Nanotechnology Materials and Devices Conference, Oct 18, 2011 - Oct 21, 2011 Jeju, Korea, Jun 20, 2011
13. ASQED 2011 Asia Symposium on Quality Electronic Design Jul 19, 2011 - Jul 20, 2011 Kuala Lumpur, Malaysia, Apr 23, 2011
14. IEEE NANO 2011 11th IEEE Conference on Nanotechnology Aug 15, 2011 - Aug 18, 2011 Portland, Oregon, USA, Apr 1, 2011
15. MS&T 2011 Materials Science & Technology 2011 Conference & Exhibition Oct 16, 2011 - Oct 20, 2011 Columbus, Ohio, USA, dead line over.
16. INTERNATIONAL SYMPOSIUM ON ADVANCED COMPLEX INORGANIC NANOMATERIALS, Université Catholique de Louvain, Belgium, Namur 11 Sep 11- 14 Sep 11
17. Nanomaterials: Regulations, Risks and Rewards, Hotel Fira Palace, Barcelona, Spain, Sept 07 - 08, 2011
18, Cochin Nano-2011 - Third International Conference on Nanoscience and Technology, Aug 14 - 17, 2011, Convention Center, IMA Hall, Cochin, Kerala, India
19. 11th International Conference on Nanotechnology (IEEE NANO 2011), Waterfront Hotel, Marriott Downtown, Portland Oregon US, Aug 15 - 18, 2011
20. The Fifth International Conference on Quantum, Nano and Micro Technologies, French Riviera - location TBD ICQNM 2011, France, Aug 21 - 27, 2011
21. NanoScience + Engineering 2011 - Part of SPIE Optics + Photonics, San Diego Convention Center, San Diego California United States, Aug 21 - 25, 2011
22. CDES 2011 The 2011 International Conference on Computer Design Jul 18, 2011 - Jul 21, 2011 Las Vegas, Nevada, dead line over.
23. The International Conference for nanomaterials Synthesis and Characterization 2011, Mines Wellness Hotel, Seri Kembangan Selangor Malaysia, July 04 - 05, 2011
24. Chirality at the Nanoscale, Liverpool Merseyside, UK, Merseyside Maritime Museum 2nd Conference, July 09 - 10, 2011
25. Workshop and Exhibition in Nanotechnology ICWEN Egypt 2011, Egypt International Conference, Cairo Egypt, July 10 - 12, 2011
26. 2nd International Conference on Nanotechnology: Fundamentals and Applications, University of Ottawa, Ottawa, Ontario Canada, July 27 - 29, 2011
27. ICNFA 2011 2nd International Conference on Nanotechnology: Fundamentals and Applications, Jul 27, 2011 - Jul 29, 2011 Ottawa, Canada
28. INEC 2011 IEEE 4th International Nanoelectronics Conference, Jun 21, 2011 - Jun 24, 2011 Tao-Yuan, Taiwan
29. Nanomaterials 2011, Hotel Russell, Great Britain, June 07 - 09, 2011
30. Pharmceutical Nanotechnology: Applications & Commercilisation, Copthorne Tara Hotel, London UK, June 29 - 30, 2011
31. EuroNanoForum 2011, Budapest Congress and World Trade Center, Budapest Hungary, May 30 - June 01, 2011
5/25/11 5
The gold nanoparticles are the most employed amongst the different metallic nanoparticles in the fields of nanomedicine and nanobiotechnology. Preparation and synthesis of gold nanoparticles with small size, suitable stability, high activity and efficiency is very important and applicable particularly in medicine.
Synthesis
Gold nanoparticles can be synthesized and stabilized by peptides, proteins, DNA and chemical/biological polymers. The reducing reagents could be either inorganic such as sodium/potassium borohydrate, hydrazine and salts of tartarate, or organic ones like, sodium citrate, ascorbic acid and amino acids capable of being oxidized. Various reagents serve as stabilizing agent to make the nanoparticles formed to be stabile for further use. These include the polymers such as different kind of polyethyleneglycol, polyvinyl alcohol, polyvinyl pyrilidon and the surfactant viz, sodium dodycel sulfate, tween 80, triton and carbohydrates like chitosane.
Chemical reduction
Chemical reduction technique employing L-Tryptophane as reducing agent can be used to synthesis gold nanoparticles. In this method, solutions of HAuCl4.3H2O, L-Tryptophane and polyethyleneglycol 1000 are prepared. Gold nanoparticle synthesis is done by Turkevich method. In this method, HAuCl4.3H2O is heated to its boiling on a magnetite stirrer, to which, reducing agent is injected. Heating is continued till the color of the solution changed from colorless to pink/red. Few milliliter of polyethyleneglycol 1000 at room temperature is added to the above solution. The formed gold nanoparticles are stable and the diameter of the nanoparticles can range from 10-25 nm. While synthesizing gold nanoparticles, reduction of anions is important and this is brought about by tryptophane. Such gold nanoparticles have promising application in nanomedicine, nanobiotechnology and other related fields.
5th annual NanoMaterials conference on
NanoMaterials 2011
Date: Tue, 2011-06-07 - Thu, 2011-06-09
Location: Hotel Russell, London
Website: http://www.nanomaterials-conference.com
The event will deliver an outstanding learning and networking platform for anyone involved with commercialised nanotechnology.
Topics
Building on its conceptual origin, the 5th edition of this unrivalled event will focus on topics such as innovation, success stories, strategy and policy. The event’s main aim being promotion of progress and new ideas, NanoMaterials will follow this trend and deliver new programme structure in 2011.
NanoMaterials 2011 will feature 2 plenary sessions and 3 parallel sessions with a change in focus from the previous editions. These 3 programme tracks will focus on:
• Policy, Business & Finance:
Navigating the regulatory landscape, securing project funding and how to do business in the global nanomaterials marketplace
• Synthesis and production:
Manufacturing efficiencies, upscaling, production management and quality control
• Innovations in nanomaterials
The latest developments in nanomaterials, testing and characterisation across a broad spectrum of end-use applications
Opening plenary session in the morning of day 1 and the closing plenary session in the afternoon of day 2 will present senior industry players providing real insight into key issues that affect the entire commercialised nanotechnology supply chain.
The event will be complemented by an exhibition showcasing leading suppliers of products and services, a poster display, 1-2-1 Networking Event, a pre-conference workshop and extensive social programme.
Engineers at the University of Ulster have created ultra thin, stable diamond nanorods with a diameter as thin as few nm and smaller than all the currently reported diamond 1D nanostructures.They exhibit a low-threshold, high current-density with field emission performance better than that of all other conventional (Mo and Si tips, etc.) and popular nanostructural (ZnO nanostructure and nanodiamond, etc.) field emitters except for oriented CNTs. Such diamond nanorods are encapsulated in a few graphene layers, which serve as a shield for keeping them stable. The ultra thin DNR is encapsulated in tapered carbon nanotubes (CNTs) in a specific orientation. DNRs are self-assembled into isolated electron-emitting spherules along with diamond nanoclusters and multilayer graphene nanowires. The forming mechanism of DNRs is suggested based on a heterogeneous self-catalytic vapor solid process.
Fabrication
The ultra thin nanords were fabricated in a microwave plasma assisted chemical vapor deposition reactor using a mixture gas of nitrogen and methane gases. Together with some diamond nanocluster, graphene nanowires and carbon nanotubes, diamond nanorods are self-assembled into a spherical electron-emitting structure. This integrated self assembled nanostructure has excellent field electron emission performance, better than that of all other conventional (Mo and Si tips, etc.) and popular nanostructural feld emitters. This novel DNR-based integrated nanostructure has a potential for use as low-power cold cathodes as well as for medical technological applications.
5/22/11
Researchers in China have reported a nanowire-based biofuel cell (NBFC) based on a single proton conductive polymer nanowire for converting chemical energy from biofluids into electricity, using glucose oxidase and laccase as catalyst. Single nanowire biofuel cell for harvesting chemical/biochemical energy can also be used for powering in vivo nanodevices such as pH, glucose or photon and biosensing sensors. The high power output, low cost and easy fabrication process, large-scale manufacturability, high 'on-chip' integrability and stability demonstrates its great potential.Working
In the single Nafion/poly(vinyl pyrrolidone) compound nanowire-based biofuel cell the nanowire lies on a substrate, with both ends tightly bonded to the substrate and outlet interconnects. GOx and laccase are used as catalysts in the anode and cathode region, respectively. The NBFC is immersed into a biofuel solution and two chemical reactions occur in the anode and cathode regions, creating a corresponding chemical potential drop along the nanowire, which drives the flow of protons in the nanowire and electrons through the external load. The biofuel cell of a single nanowire generates an output power as high as 0.5-3 µW in glucose solution, in human blood and the juice of a watermelon. It has been integrated with a set of nanowire based sensors for performing self-powered sensing.
Fabrication
The proton exchange membrane composed of Nafion film is the key component in many types of fuel cells and because of this component it is very difficult to minimise the size of a fuel cell. Researchers have fabricated Nafion nanowires, which have an enhanced performance of proton conductivity compared with Nafion film. The Nafion nanowires have a diameter about 100 nm to 1 µm, and a length of about 20 µm. However, it turns out to be very difficult to build a platinum-catalyzed fuel cell on such a small nanowire as the anode and cathode reacting area needs to be strictly separated.
Nafion nanowires can be fabricated by electrospinning method easily as long as centimeters and it is very easy to build a fuel cell based on an individual nanowires.
Biofuel cell with an enzyme pair (such as GOx and Laccase) used as catalysts can be fabricated in a miniature size as against a chemical fuel cell. In the biofuel cell the anode and cathode area need not to be separated since enzymes are very selective to the reactants, for example, the GOx will only oxidize glucose, while Laccase will only reduce oxygen in the biofluid.
Nafion nanowires can be fabricated by electrospinning method easily as long as centimeters and it is very easy to build a fuel cell based on an individual nanowires.
Biofuel cell with an enzyme pair (such as GOx and Laccase) used as catalysts can be fabricated in a miniature size as against a chemical fuel cell. In the biofuel cell the anode and cathode area need not to be separated since enzymes are very selective to the reactants, for example, the GOx will only oxidize glucose, while Laccase will only reduce oxygen in the biofluid.
Output
The power output in glucose-containing PBS buffer solution can reach up to 2.7 µW at a power output density of around 30 µW cm-2 while the NBFC driven by blood glucose gives 0.5 µW. NBFC can work even using watermelon juice as the biofuel.
Applications
Applications
Biofuel cell has potential applications in powering in vivo wireless nanodevices. Researchers have shown that nano biofuel cell can be directly integrated with a single nanowire-based nanosensor for building a self-powered chemical - or bio-sensor. Self-powered nanosensor can be made by integrating an NBFC with a single nanowire-based pH sensor or glucose sensor fabricated using ZnO nanowires. Thus NBFC provides a new approach for self-powered nanotechnology that gives electricity in applications such as implantable biomedical devices, wireless sensors, portable electronics that are important for biological sciences, environmental monitoring, defense technology, personal electronics, electrical measurement system, data processing logic system and possibly wireless communication unit and even to power a heart cardiac pacemaker by generating power from human blood.
Building a Two-Chamber Microbial Fuel Cell
The website (www.engr.psu.edu/.../bioenergy/mfc_make_cell.htm) gives a clear idea to build a microbial fuel cell (MFC) using relatively inexpensive and readily available materials.
Example
Researchers at Joseph Fourier University in Grenoble, France have successfully developed a glucose based biofuel cell (GBFC). Current devices which operate on batteries must be surgically removed when they run out of power. But these GBFCs, are about the size of a couple of pennies stuck back-to-back (much smaller than current batteries). The graphite-based cell is wrapped in a clear dialysis bag, and contains on each side different enzymes that digest oxygen from air and sugar from food, respectively. As the enzymes break down those molecules, they create an electrical charge.
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5/21/11
Nanoscale lubricationFriction and wear are major causes of mechanical failures and dissipative energy losses in industries such as in the automotive, aerospace and manufacturing industries. This energy loss could be saved by the proper use of lubricants. Friction depends on the two surfaces in contact, the operating conditions, the sliding velocity, and so on and the fact is that friction is a very complicated phenomenon, little understood fundamentally, and dependent on processes taking place at the nanoscale.To minimize frictional energy losses both solid and liquid lubricants have been developed which will reduce equipment maintenance and prolong component lifetime. Application of various types of lubricants alone does not solve the problem. These issues are studied with great focus by emerging technologies at the nanoscale.
Lubrication
Lubrication is the application of a substance capable of reducing friction, heat, and wear when introduced as a film between solid surfaces which is necessary to reduce damage to the moving surfaces and to enable reliable operation. Fundamentally, the phenomena of friction, wear, and lubrication involve molecular mechanisms occurring on a nanometer scale, and hence a good understanding of lubricant behavior on this scale is critical to developing new technologies for reduction of loss due to friction. Conventional lubrication schemes rely on the formation of a solid or liquid interface between mating parts where a lubricant slides against itself. But application of liquid lubricants causes the viscosity of the fluid to impede motion of micro - and nanoscale parts and surface tension can cause these parts to warp and adhere.
Nanoscale lubrication
Tribological principles applicable to micro - and nanoscale devices (i.e., nanotribology) focus primarily on surface interactions at the original interface to controlling friction at the nanoscale. To solve this problem researchers are developing techniques to perform fundamental measurements of atomic - and nanoscale forces to determine the contributions to these forces from individual material properties, including electrical conductivity, thermal conductivity, structure and composition. This can be done by using instruments like Raman spectroscopy with high-speed, high-resolution atomic force microscopy for the in situ measurements of the thermal properties of materials.
AFM has allowed to study the interaction between approaching surfaces at length and force scales that were previously unattainable and understand the science of adhesion, lubrication, friction and wear can now be understood at the sub-nanometer scale.
Georgia tech researchers have come to the following conclusions:
Viscosity and other concepts that we commonly use are taken from bulk behavior, and one of the questions we must answer is whether it is appropriate to adopt the same concepts on the molecular levels.
Increased friction caused by nanoconfinement-induced layering poses a significant concern for future devices. But the researchers have proposed several countering techniques:
• Chemically altering the long-chain molecules to include branched structures that inhibit the formation of layers. The researchers have shown that a nanoconfined liquid made of branched alkane molecules has a lower viscocity then a confined liquid of the same molecular weight but made of straight chain molecules. This behavior is opposite to that found in much larger environments.
• Roughening the surfaces of the confining plates to disrupt the molecular ordering. Instead of forming ordered layers, the molecules closest to the rough surfaces adhere to them, leaving free-flowing molecules in between.
• Varying the distance between the two confining surfaces in an oscillatory manner, just enough to keep the lubricant molecules in a "frustrated" state of disorder. Varying the distance by one Angstrom in a 20-Angstrom gap should be enough to prevent the layering. The frequency of the applied oscillations depends on the characteristic molecular relaxation times and the viscosity of the lubricant, which in turn are governed by the nature and structure of the fluid molecules.
Engine lubrication
Modern engine lubricating oil is a complex, highly engineered mixture, up to 20 percent of which may be special additives to enhance properties such as viscosity and stability and to reduce sludge formation and engine wear. But, unfortunately phosphorus is a chemical poison for automobile catalytic converters, reducing their effectiveness and life span, so industry chemists have been searching for ways to replace or reduce its use.
Researchers of National Institute of Standards and Technology have established that a titanium compound added to engine oil creates a wear-resistant nanoscale layer bound to the surface of vulnerable engine parts, making it a credible substitute for older compounds that do not coexist well with antipollution equipment.
US researchers have shown that hybrid lubricants developed by them simultaneously exhibit lower interfacial friction coefficients, enhanced wear and mechanical properties, and superior thermal stability in comparison with nanocomposites created at low nanoparticle loadings.
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Nanotechnology can be used to extend shelf life of food. A nanocomposite coating process could improve food packaging by placing anti-microbial agents directly on the surface of the coated film.Nanocomposites could increase or decrease gas permeability of different fillers as is needed for different products. They can also improve the mechanical and heat-resistance properties and lower the oxygen transmission rate.
Safety package
“Smart” safety packaging can be used to wrap food that can detect spoilage or harmful contaminants and release nano-anti-microbes to extend food shelf life. Products will be developed in future to enhance and adjust the food color, flavor, or nutrient content to accommodate each consumer’s taste or health needs. ‘Smart’ packaging could also release a dose of additional nutrients to those which it identifies as having special dietary needs, for example calcium molecules to people suffering from osteoporosis.
Nano wrapper
Nano wrapper has been developed to envelope foods, preventing gas and moisture exchange. Nanomaterials are used in packaging, like beer bottles, as a barrier, allowing for thinner material, with a subsequently lighter weight, and greater shelf-life. Nanoclays help to hold the pressure and carbonation inside the bottle, increasing shelf life. Nanoclays and nanocomposites can be used for a variety of uses, including flame retardants, barrier film (as in juice containers), and bottle barrier.
Nano clay barrier
Researchers from Texas A&M University have developed nano- barrier composed 70 percent out of clay and the rest made from various polymer materials. Existing packaging can be coated to keep food fresh and flavorable for longer. The film is less than 100 nanometers thick and 100 times more oxygen-impermeable than the silicon oxide coatings of existing food packaging.
The nano- barrier utilizes montmorillonite clay, an ingredient commonly used to make building bricks. When viewed under a microscope, the nano- barrier structure resembles bricks and mortar. It's this structure that makes the nano- barrier such a strong reinforcement to existing packaging and gives thousands of times more permeable than film having the most organized structure with oxygen-impermeable film.
Manufacturers currently use a variety of packaging materials to preserve food and beverages, but these materials often have drawbacks. Silicon oxide, though it provides a barrier to oxygen, still under-performs the nano- barrier when it comes to preserving food. Plastic packaging that uses a thin coating of metal, besides being un-microwaveable, can be unappealing to consumers who want to see their food purchase. The nano- barrier coating will give consumers tastier, longer-lasting foods and help boost the food packaging industry.
Researchers have created two tiny instruments capable of detecting a range of contaminants, from molecules to whole bacteria, in food and water. The device can be arranged to search for specific things, for example, if the organism to be detected is E. coli, the cantilever could be coated in antibodies specific to E. coli cells. Many different molecules or organisms can also be recognized simultaneously. The applications for this new technology are abundant. The sensors can detect DNA and hence may be used to test for human genetic diseases. They are also extremely sensitive and can measure deflections of just one nanometre, so are able to detect the presence of very small molecules. A whole bacteria and even parts of bacteria can be identified, making the sensors ideal for testing the quality of water and food samples. A lid device with tiny instruments could be included in food packaging. When a food is infected, the control unit in the plastic wrapping becomes coloured and thus the simple colour indicator can show the quality of the food. It requires no external energy and is cheap to make. 5/20/11
Nanofluidics is often defined as the study and application of fluid flow in and around nanosized objects and deals with the manipulation and control of a few molecules or minute quantities of fluids. The invention and wide availability of many new technological tools like atomic force microscope (AFM) and scanning tunneling microscope (STM) (both for inspection and creation of nanostructures), the electron, X-beam and ion-beam lithographs, and the development of new micromachining techniques like soft lithography and bottom-up assembly methods has made the study and application of nanofluidics much more accessible, and allows a previously unknown measure of control on the nanoscale.Applications
Nanofluidic devices are made by etching tiny channels on silicon or glass wafers, typically using photolithography. These devices have relatively simple structures, with the branched channels having the same depths.
Nanofluidics finds application in many diverse fields; particularly biology is an important discipline for nanofluidics, because biological organisms on their primary cellular level function in a nanofluidic environment. A number of applications of nanofluidics have already been use, like the use of charged polymers for lubrication, the lotus effect for self-cleaning surfaces, membranes for filtering on size or charge (e.g. for desalination) and nanoporous materials for size exclusion chromatography. In separation science it is used for the size fractionation in regularly structured micro arrays. Another area of nanofluidic applications has been the study of fundamental properties of liquids and molecules, e.g. in biophysics and fluid mechanics, where nanofluidics offers the possibility to confine molecules to very small spaces or to subject them to controlled forces and to extract fundamental knowledge.
Nanofluidic devices have been mainly used to analyze DNA and proteins; it could also be useful in the preparation of nanoparticles for gene therapy, drug delivery, and toxicity analysis. The device could be useful for sorting and measuring nanoparticles that are employed for drug delivery and gene therapy.
Nanofluidic structures are naturally applied in situations demanding that samples be handled in exceedingly small quantities, including Coulter counting, analytical separations and determinations of biomolecules, such as proteins and DNA, and facile handling of mass-limited samples. Application of nanofluidics is also to Nano-optics for producing tunable micro lens array, development of lab-on-a-chip devices for PCR and related techniques.
Challenges
There are many challenges associated with nanofluidics when applied to the flow of liquids through carbon nanotubes and nanopipes because of channel blocking due to large macromolecules and insoluble debris in the liquid.
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The Air Quality Engineering research lab at Virginia Tech is conducting a study of the cross-media (air, water, AND soil) fate of nanoparticles in the environment. This video summarizes the background and motivation for the research.
Nanoparticles can play a vital role in the biomedical field. Magnetisable particle and an AIDS virus antibody are boubd together because of their positive and negative charges and if the virus is present, the antibody recognises and sticks to it.
A video on using Gold nanoparticles to target EGFR on cancer cells for easy detection
A focus on Micro, Precision and Nano Manufacturing Technologies
An entertaining and useful explanation of the differences between the micro- and nano-particle techniques used for cell isolation / cell separation from the video presentation of YOUTUBE; Cell Isolation - The Two Worlds of Cell Separation
Articles from RICE (mentioned in video): http://bit.ly/gPytFD, http://bit.ly/gXo3KY, http://bit.ly/i5i8kI, http://bit.ly/ergkVa
Article by Dr. Shenoy (mentioned in video): http://bit.ly/dLZPqf
Article on cellular responses to dextran-derivatised iron oxide nanoparticles: http://bit.ly/i4BPbQ
Article on uptake of dextran-coated nanoparticles: http://bit.ly/fQEU5d
Article indicating induction of forced cellular iron elimination of nanoparticles: http://bit.ly/i72Nnd
Article on iron oxide nanoparticle toxicity: http://bit.ly/gUTAeu
Article on polystyrene nanosphere toxicity: http://bit.ly/heJWJp
Article on nanoparticle impacts on gene expression: http://bit.ly/fQ58wx
Article on cell response to dextran-derivatised iron oxide nanoparticles post internalization: http://bit.ly/hbhWnH
Article on dextran derivatised iron oxide nanoparticles and their influence on fibroblasts: http://bit.ly/dW1CCy
Article on nanoparticle cytotoxicity and changes in cytokine induction: http://bit.ly/dFdifn
Article on immunotoxicity of nanoparticles: http://bit.ly/dFGkyX and http://bit.ly/ggkhjr
Article on metal oxide nanoparticle toxicity: http://bit.ly/fphwwh
Article on receptor mediated endocytosis of nanoparticles: http://bit.ly/hMk7vM
From the fields of nanomedicine and nanotoxicology: http://bit.ly/gpMsA7, http://bit.ly/cDOxDn, http://bit.ly/gv71Wp, http://bit.ly/frF180, http://bit.ly/fTJTf8, http://bit.ly/17wHLO
Journal dedicated to nanotoxicology: http://informahealthcare.com/nan
More refs: http://en.wikipedia.org/wiki/Nanoparticles#Safety
The European Commision's initiative on the potential harmful effects of nanoparticles: http://bit.ly/g4gnUo
An entertaining and useful explanation of the differences between the micro- and nano-particle techniques used for cell isolation / cell separation.
Andrew Maynard, chief science advisor for the Project on Emerging Nanotechnologies, talks about the technology's risks.
A molecular assembler hard at work designing a new laptop computer.
Let's hope this becomes a future reality.
5/18/11
Nanotechnology Nanotechnology provides clinical medicine with a range of new diagnostic and therapeutic opportunities such as medical imaging, medical diagnosis, drug delivery, and cancer detection and management. For example manganese, polystyrene, silica, titanium oxide, gold, silver, carbon, quantum dots, and iron oxide and other nanomaterials have made an impact in the development of new analytical tools for biotechnology and life sciences.
Stem cell labeling
The roles of stem cells are under intensive investigation in therapeutic and regenerative medicine, such as regenerating cardiomyocytes, neurons, bone, and cartilage. To track the real-time changes of cell location, viability, and functional status, cell imaging techniques have been introduced during the last few years. Cells of interest are labeled with reporter genes, fluorescent dyes, or other contrast agents that transform the tagged cells into cellular probes or imaging agents. MRI is used for cell tracking with high spatial resolution high anatomic background contrast, but MRI signals cannot indicate whether cells are dead or alive.
Nanoparticles are commercially available as ferro fluids consisting of an aqueous dispersion of magnetic iron oxides with a starch coating. To screen cells in vivo, several techniques have been described using nanoparticles like quantum dots, pebbles and super paramagnetic iron-oxide nanoparticles. The nanoparticle-labeled stem cells for tracking have been found very successful. Nanoparticles are resistant to chemical and metabolic degradation, demonstrating long term photostability. For example Quantum Dots (QDs) offer an alternative to organic dyes and fluorescent proteins to label and track cells in vitro and in vivo.
Labeling of stem cells with nanoparticles overcame the problems in homing and fixing stem cells to their desired site and guiding extension of stem cells to specific directions. Although the biologic effects of some nanoparticles have already been assessed, information on toxicity and possible mechanisms of various particle types remains inadequate.
5/18/11 0
NanomaterialsGenerally nanomaterials are considered as those with one of their structural features of size less than 100nm. nanomaterials have a wide variety of potential applications in biomedical, optical, and electronic fields. Nanoparticles are of great scientific interest as they are effectively a bridge between bulk materials and atomic or molecular structures. Many of these nanomaterials are made directly as dry powders, but they will rapidly aggregate through a solid bridging mechanism in as little as a few seconds. To keep the nanoparticles as such they are prepared and stored in a liquid medium in order to have sufficient interparticle repulsive forces and stay without aggregation. The composition of the nanoparticle is briefly explained below.
Composition
Nanoparticle consists of two main parts, a core and an outer organic stabilizing layer.
Inner core
The core can be made out of a variety of materials and it is responsible for the optical and electrical properties as it confines electrons to the physical dimensions of the particle. This leads to well known quantum “confinement” effects dictated by quantum mechanics. The core is nearly identical to the crystal structure of the parent (bulk) material and may be thought of as a much smaller fragment of the bulk lattice. NP may be spherical, cubes, rods and other non-spherical shapes.
Outer organic shell
The second major aspect of the NP is its outer organic shell. In the case of the solution-phase synthesis of colloidal nanomaterials, structure is stabilized in order to prevent aggregation of the particles. For some of the NPs the stabilizing layer will consist of simple organic surfactants which provide steric stabilization of the particles. Nanoparticles located in close proximity undergo a repulsive potential arising from surface bound organic molecules. Alternatively, they can be stabilized by electrostatic means, based on the Coulomb repulsion of like charges to prevent particle agglomeration.
General structure
The general structure of the organic passivating ligand consists of a head group that “sticks” to the NP surface via dative bonds, actual covalent bonds or electrostatic attraction. The surfactant molecule also possesses a “tail” which points away from the nanoparticle surface and extends into the surrounding liquid medium. The polar/nonpolar nature dictates the NP solubility within surrounding organic or aqueous media. The organic shell plays a relevant role even in the quantum efficiency of the nanoparticles, their stability in different media and prevents high electrical conduction.
Stabilization
For many chemically synthesized NPs, their primary solubility will be within organic solvents. The surfactant molecules also provide electronic stabilization of the NP by coordinating to dangling bonds on the surface. These dangling bonds stem from the abrupt termination of the NP core. If not taken into account, they may lead to defect related contributions to the NP optical and electrical properties. As a consequence, for this and other abovementioned reasons, the synthesis and development of colloidal NPs is as much about the growth of the core as it is about the choice of organic surfactants passivating their surfaces.
5/17/11
Gold nanoparticles have photonic and biocompatible properties and hence they are widely used in electronic wiring, optics, photonics, optoelectronics, catalysis and biomedicine. But the intrinsic characteristics of gold nanoparticles are primarily dependent on their size and shape obtained by different synthesis methods. In general, gold nanoparticles are produced in an aqueous solution through the reduction of chloroauric acid (HAuCl4). Of these methods, Turkevich water based and Brust organic liquid based methods are the most widespread used approaches, but both the methods require a reducing agent to reduce Au3+ ions to neutral gold atoms, and a suitable stabilizer to prevent the synthesized gold nanoparticles from aggregation.Methods
Turkevich method
In the Turkevich method, sodium citrate is usually used as both the reducing agent and the stabilizer, although other reductants, such as amino acids can also be used. Using this method spherical gold nanoparticles around 10-20 nm in diameter suspended in water can be produced. The particle size can be increased by reducing the amount of sodium citrate.
Brust method
In the Brust method, sodium borohydride (NaBH4) and tetraoctylammonium (TOAB) are used as the reducing agent and the stabilizer, respectively. The synthesized gold nanoparticles are around 5-6 nm.
Reductant and stabilizer-free approach
A reducing agent and stabilizer free method is based on the electrochemical deposition technique. The barrier layer of an anodic aluminum oxide (AAO) film is used as the template; a gold thin film is deposited on the surface of the barrier layer; gold nanoparticles are then uniformly deposited on the gold thin film by electrochemical deposition. The distribution density and size of the nanoparticles can be well controlled by the applied potential for the electrochemical deposition.
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5/15/11
A software program called Quantitative Electron Diffraction (QED) has been developed to go along with transmission electron microscopes to study the structure of crystalline materials by collecting information on the Large-Angle Rocking-Beam Electron Diffraction patterns emitted. Crystal structure
Crystal structure of material is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry. Patterns are located upon the points of a lattice, which is an array of points repeating periodically in three dimensions. Crystal structure is studied by transmission electron microscopes.
TEM
Transmission electron microscopes (TEM) create magnified images of samples and are, in contrast to the light microscope, even able to resolve individual atoms. When transmitting a beam of electrons through a crystalline sample such as a complex mineral or a crystallized protein, the electrons are diffracted in a specific way. Collecting such electron diffraction patterns of a sample from several different directions uniquely identifies a specific crystal structure.
Electron diffraction
Electron diffraction is a collective scattering phenomenon with electrons being (nearly elastically) scattered by atoms in a regular array (crystal). This can be understood in analogy to the Huygens principle for the diffraction of light. The incoming plane electron wave interacts with the atoms, and secondary waves are generated which interfere with each other. This occurs either constructively by reinforcement at certain scattering angles generating diffracted beams or destructively by extinguishing of beams.
LARBED
LARBED (Large-Angle Rocking-Beam Electron Diffraction) patterns are composed of a series of diffraction patterns collected for a large range of directions of the electron beam. Although collected for a single specimen orientation such LARBED patterns provide 3-dimensional information and thus enable researchers to better extract information about the structure of crystalline materials in various fields of applications such as materials science, geology and life sciences.
Software
A software program called Quantitative Electron Diffraction (QED) has been developed to analyze huge data collected from the diffraction patterns and extract information on crystal structure. The QED software can control almost any transmission electron microscope to automatically collect LARBED patterns. The new software for automated acquisition of LARBED patterns works by controlling the tilt angle and position of a collimated electron beam. The QED software compensates the beam shift with the help of the illumination system of the microscope. Thus data about characteristics from nano-sized samples can be collected. LARBED data contain an enormous amount of information about examined specimen, including specimen thickness, the absolute values of structure factors, the crystal symmetry even of very thin (<10 nm) samples, as well as the specimen surface orientation. LARBED is a patented procedure, which has been developed at the Max Planck Institute for Intelligent Systems in Stuttgart, Germany and released by HREM Research Inc., Japan. The advantage of LARBED is that it overcomes difficulties caused by multiple scattering of electrons passing through a sample. This dynamical scattering makes it, amongst other things, difficult to analyze the intensities of the diffracted beam when using other methods based on electron diffraction. This leads to the loss of valuable information and allows transmission electron microscopes to acquire novel kinds of data, opening up new possibilities in electron crystallography.
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5/14/11
Information and communication technology is an important and rapidly growing industrial sector with a high rate of innovation. Enormous progress has been made by making a transition from traditional to nanotechnology electronics. Nanotechnology has created a tremendous change in information and communication technology.
Breakthrough areas
Breakthrough in information and communication technology due to nanotechnology can happen in two steps. First step is top-down miniaturization approach which will take conventional microstructures across the boundary to nanotechnology. Secondly, in the longer term, bottom-up nanoelectronics and nanosystem engineering will emerge using technologies such as self-organization process to assemble circuits and systems.
Developments
Development are taking place on ultra-integrated (opto)electronics combined with powerful wireless technology as low-price mass products, ultra miniaturization, the design of innovative sensors, production of cheap and powerful polytronic circuits, novel system architectures using nanotechnology for future DNA computing which is interface to biochemical processes and quantum computing which can solve problems for which there are no efficient classical algorithms. Due to the development of nanoelectronic components, quantum cryptography for military and intelligence applications is emerging.
Memory storage
Memory storage before the advent of nanotechnology relied on transistors, but now reconfigurable arrays are formed for storing large amount of data in small space. For example, we can expect to see the introduction of magnetic RAMs and resonant tunnel elements in logical circuits in the near future. Every single nanobit of a memory storage device is used for storing information. Molecular electronics based on carbon nanotubes or organic macromolecules will be used.
Semiconductors
Nano amplification and chip embedding is used for building semiconductor devices which can even maintain and neutralize the electric flow. Integrated nanocircuits are used in the silicon chips to reduce the size of the processors. Approaches promising success in the medium term include e.g. rapid single-flux quantum (RSFQ) logic or single electron transistors.
Display and audio devices
Picture quality and resolution of display devices has improved with the help of nanotechnology. Nanopixelation of these devices make the picture feel real. Similarly frequency modulation in audio devices has been digitized to billionth bit of signals.
Data processing and transmission
In the field of data processing and transmission development of electronic, optical and optoelectronic components are expected to lead to lower cost or more precise processes in the field of manufacturing technology. Development of nanoscale logical and storage components are made for the currently dominant CMOS technology using quantum dots and carbon nanotubes. Photonic crystals have potential for use in purely optical circuits as a basis for future information processing based solely on light (photonics). In molecular electronics, nanotechnology can be used to assemble electronic components with new characteristics at atomic level, with advantages including potentially high packing density. Smaller, faster and better components based on quantum mechanical effects, new architectures and new biochemical computing concept called DNA computing are possible with nanotechnology. The new phenomenon, called the "quantum mirage" effect, may enable data transfer within future nanoscale electronic circuits too small to use wires.
Future nanotechnology areas
Nanotechnology is the next industrial revolution and the telecommunications industry will be radically transformed by it in the future. Nanotechnology has revolutionized the telecommunications, computing, and networking industries. The emerging innovation technologies are:
*Nanomaterials with novel optical, electrical, and magnetic properties
*Faster and smaller non-silicon-based chipsets, memory, and processors
*New-science computers based on Quantum Computing
*Advanced microscopy and manufacturing systems
*Faster and smaller telecom switches, including optical switches
*Higher-speed transmission phenomena based on plasmonics and other quantum-level phenomena
* Nanoscale MEMS: micro-electro-mechanical systems
5/14/11 1
Gold nanoparticlesThe photonic and biocompatible properties of gold nanoparticles have been widely exploited for use in electronic wiring, optics, photonics, and optoelectronics, for analytical separation of organic compounds, catalysis and biomedicine. The intrinsic characteristics of gold nanoparticles are primarily dependent on their size and shape.
Production
In general, gold nanoparticles are produced in an aqueous solution through the reduction of chloroauric acid (HAuCl4). Of various methods, Turkevich water based and organic liquid based method of Brust are the most widespread used approaches. Both the Turkevich and Brust methods require a reducing agent to reduce Au3+ ions to neutral gold atoms, and a suitable stabilizer to prevent the synthesized gold nanoparticles from aggregating.
In the Turkevich method, sodium citrate is usually used as both the reducing agent and the stabilizer, although other reductants, such as amino acids have also been successfully used. Spherical gold nanoparticles of around 10-20 nm in diameter suspended in water can be produced. The particle size can be increased by reducing the amount of sodium citrate.
Turkevich modified method
Gold nanoparticles can be synthesized by chemical reduction method of Turkevich. The synthesis of gold nanoparticles by this method requires the reduction of AuCl−4 ions to gold nanoparticles. The synthesis can be done by a modified Turkevich method. Solutions of HAuCl4.3H2O, L- In this method tryptophane and polyethylene glycol 1000 at concentration of 2.25 mM and 3.3% were prepared respectively. Then 10 mL of HAuCl4.3H2O is heated to its boiling on a magnetite stirrer, to which, 15 mL of reducing agent is injected. Heating is continued till the color of the solution changes from colorless to pink/red. Three milliliter of 3.3% polyethylene glycol 1000 at room temperature is added to the above mentioned solution. Thus AuCl−4 ions are reduced to gold nanoparticles.
5/13/11
Water purification methodsWater purification methods available now work on the use of ultraviolet light or involve a suspension of nanoparticles. The ultraviolet light method is relying on a good source of UV light and in the other method suspended nanoparticles have to be recovered after the water purification process is over.
Zinc oxide nanorods
Zinc oxide nanorods have been used for destroying bacterial contaminated water. Nanorods grown on glass substrates and activated by visible light of solar energy have been found to be effective in killing both gram positive and gram negative bacteria by a team of researchers at the Asian Institute of Technology, Thailand. This discovery has immense possibilities for cheaper and environmentally friendly purification of water.
Principle
Deliberate defects are incorporated in ZnO nanorods grown on glass by creating oxygen vacancies and interstitials, which then allows visible light absorption. In the absence of light, ZnO dissolves slowly and releases zinc ions having anti bacterial properties to penetrate the bacterial cell envelope. This retards the growth of microbes, but under illuminated conditions the zinc ions get doubled due to photo catalysis and destroy the microbes. An electron degradation mechanism dominates the photo catalytic processes of ZnO material.
Benefits
Such ZnO nanorods have been tested on Escherichia coli and Bacillus subtilis bacteria and the working of this method under sun light instead of UV light has a higher potential for huge commercial application. The levels of zinc ions removed from the rods to the water are safe for human consumption according to the researchers.
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5/9/11
NanoelectrodesNanoelectrodes are electrodes with a critical dimension in the range of one to hundreds of nanometers and include individual electrodes, nanoelectrode ensembles, and arrays. Metallic nanowires, carbon nanotubes, magnetic nanoparticles and metal oxide nanowires have been employed to fabricate nanoelectrodes and platforms. The development of a nanobiosensor based on individual nanoelectrodes and nanoelectrode arrays or nanoelectrode ensembles offers unprecedented avenues for screening and detection at ultrahigh sensitivities.
Applications
Nanoelectrodes offer great advantages in many biological investigations, particularly in single cells studies, fabrication of microchips, design of coordinated biosensors, addressable patterned electrodes, ultra sensitive nanobiosensors, in the development of specific and intelligent sensors for use as direct, point of care clinical devices and to monitor biorecognition events and interactions.
Single-molecule transport
Nanoelectrode devices for single-molecule transport measurements have been fabricated using different techniques. They notably differ in the way the nanogap or the molecular junction is created. Different types of nanoelectrodes for single-molecule transport measurements are: electro migration, angle evaporation, breaks junction and nanoparticle dimmers.
Gold electrodes for biological sensors
While creating a new generation of biological sensors and nanomachines, usually nanodevices are typically built by connecting tiny components. To fix components in place biological molecules, notably DNA are used as the binding material. Researchers of University of Wisconsin-Madison use microbes for this purpose. The cells have surface proteins that attach to certain biological molecules. Once the cells are placed at specific sites on a silicon wafer, nanoparticles tagged with these molecules can bind to the cells in those locations. This is easier than dragging the nanoparticles themselves to the right spot, because their high density makes them harder to move through fluid media than the less dense living cells. The technique gives one a way to fix components such as quantum dots or carbon nanowires at very precise locations. The researchers pass a solution containing the cells over a silicon wafer with gold electrodes on its surface. The charge on the electrodes captures the Bacillus mycoides, a rod-shaped bacteria, which flow along the electrodes' edges having tiny gaps. The bacterium is trapped there by the electric field from where it can be released by reducing the voltage, or permanently immobilized by increasing the voltage to a level high enough to break its cell wall.
Carbon nanotube array to sense DNA
Multiwalled nanotubes with well-defined nanoscale geometry are attractive nanoelectrode materials. They present a wide electrochemical window, flexible surface chemistry and biocompatibility. Scientists at the NASA Ames Research Center, US, have developed an array of multiwalled carbon nanotubes that can detect low levels of DNA. To make the devices, the scientists grew vertical arrays of multiwalled carbon nanotubes on prepatterned microelectrodes by plasma-enhanced chemical vapour deposition (CVD). Then they encapsulated the nanotubes in silica grown by tetraethoxysilane CVD and used chemical mechanical polishing to flatten the surface and expose the tips of the tubes. It can be employed in enzyme-based biosensors such as glucose sensors, for antibody-antigen-based immunosensors by functionalizing appropriate biomolecules and for measuring small redox species in bulk solution.
According to researchers DNA detection can be employed into handheld devices for molecular diagnostics such as early cancer detection, point-of-care and field uses, the enzyme-based biosensors can be used for household healthcare, while pathogen sensors can be used for homeland protection.
5/9/11 0
NanomaterialsNanostructured materials can be tuned to achieve improved mechanical, electrical, optical, magnetic and other functional properties. Tailored and Tuneable properties of nanomaterials represent an important and integral part of technological developments and are now essential for future applications in the current industrial manufacturing. For example nanomaterials play a high role in today's electronic devices ranging from transistors all the way to lasers and solar-energy conversion devices or the particles could be used as a switch in an optical circuit by precisely tuning the optical properties.
Tuning or tailoring
Many different areas ranging from energy to transportation or health require specific nano-structured materials with improved functionality and reliability for the use in applications such as sensors and actuators, printable electronics, high frequency devices, friction coatings, and others. For this, two different approaches are used, namely tailoring materials on the nano-scale and develop tuneable materials.
Approaches
Tuning can be achieved in many ways using electric field, electric, chemical and electrochemical gating, temperature or light in metals and ceramics to get desired mechanical, electrical, dielectric, optical and magnetic properties.By integrating defects using dopants, point defects, dislocations and interfaces and by the control of composition and phases of materials the nanostructure can be tailored to obtain optimized properties and combinations of properties. Such approach is used for the development of materials that are far from equilibrium. As they contain large fractions of defects and disorder, the properties are directly governed by the structure.An alternative approach employs external fields to tune materials, i.e. change their properties in a reversible and reproducible manner, via modification of the electronic structure. Depending on the materials and structures or morphologies employed. Two such approaches are given below.
Coated gold nanorods
Researchers have made gold nanorods coated with silver selenide or silver sulphide (silver chalcogenides) by chemically plating the gold surface with silver and then exposing it to sulphide or selenide in an oxidising environment. Thus the resonance frequency gold nanorods can be tuned between 600 nanometres (visible light) to 2000 nanometres (infrared light). Varying the thickness of the silver chalcogenide layer changes the resonance frequency of the particles and gives the material its on-off switch effect, the lack of such a switching unit has so far limited the development of integrated nanophotonic devices. Researchers feel that production of metal nanorods with a uniform and controlled semiconductor coating is a significant synthetic achievement which may lead to the development of new devices.
Application of pressure
Researchers of Lawrence Livermore National Laboratory have developed a technique to tune nanomaterials and their fundamental properties only by applying pressure. Researchers packed quantum dot which is semiconducting materials that has its electrons confined in all three spatial dimensions into highly compacted materials gives rise to quantum dot solids, materials that present particle-particle coupling as well as electronic properties characteristic to both individual and collective particles. Researchers state that high pressure provides insight into the fundamental properties of nanoparticles, which can be drastically different from the corresponding bulk material.
5/7/11
Nanostructures
The shape, size, structure, and composition of the nanostructures determine the properties and applications. The presence of various ions has been shown to influence the shape and size of metallic nanostructures produced via the polyol method. The presence of copper(I) or copper(II) chloride in the polyol reduction of silver nitrate allows the production of silver nanowires.
Silver nanowires
Silver nanowires have been attracting more and more attention because of their intriguing electrical, thermal, and optical properties. Silver has the highest electrical conductivity among all the metals, by virtue of which Ag NWs are considered as very promising candidates in flexible electronics. Ag nanowires can be used as information guide fibers – in analogy to optical fibers – which may be integrated into micro- and nanoelectronic circuits. Production of silver nanowires, is of great significance because it a most promising candidates to be used as conductive fillers of high-performance adhesives and as catalyst.
Synthesis
For the synthesis of silver nanowires, plenty of chemical routes have been developed. Silver nitrate is reduced by ethylene glycol in the presence of poly(vinylpyrrolidone) (PVP) and copper(II) chloride by a simple synthesis using polyol method.
Ethylene glycol is polyol used in this synthesis as both the reducing agent and solvent. Ethylene glycol (5 mL) is heated at 150°C for one hour with stirring (260 rpm) in disposable glass vials placed in an oil bath. 40 μL of a 4 mM CuCl2•2H2O/ethylene glycol solution is added and heated for 15 minutes. 1.5 mL 114 mM PVP/ethylene glycol is then added to each vial, followed by 1.5 mL 94 mM AgNO3/ethylene glycol. The reaction is stopped when the solution becomes gray and wispy, after approximately one hour. The reaction is stopped by cooling the vials in cold water and the product is washed once with acetone and three times with deionized water to get nanowires of relatively uniform shape and size. The wires have a pentagonal cross-section with an average length of 10-50 μm. The yield of wires is high at 90% compared to other structures.
A variety of other surfactants (capping agent) have been developed to guide the anisotropic growth of silver nanowires and the chemical method has been the most promising way for the large-scale fabrication of silver nanowires.
A variety of other surfactants (capping agent) have been developed to guide the anisotropic growth of silver nanowires and the chemical method has been the most promising way for the large-scale fabrication of silver nanowires.
5/7/11 0
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