Use of nanoscale particles and coatings is also being pursued for drug delivery systems to achieve improved timed release of the active ingredients or delivery to specific organs or cell types. As mentioned above, information technology has been, and will continue to be, one of the prime beneficiaries of advances in nanoscale science and technology. Many of these advances will improve the cost and performance of established products such as silicon microelectronic chips and hard disk drives.
On a longer time scale, exploratory nanodevices being studied in laboratories around the world may supplant these current technologies.
Carbon nanotube transistors might eventually be built smaller and faster than any conceivable silicon transistor. Molecular switches hold the promise of very dense and therefore cheap memory, and according to some, may eventually be used for general-purpose computing. Single-electron transistors SETs 2 have been demonstrated and are.
The single-electron transistor, or SET, is a switching device that uses controlled electron tunneling to amplify current. The only way for electrons in one of the metal electrodes to travel to the other electrode is to tunnel through the insulator.
Since tunneling is a discrete process, the electric charge that flows through the tunnel junction flows in multiples of e, the charge of a single electron. Definition from Michael S. Quantum computing is a recently proposed and potentially powerful approach to computation that seeks to harness the laws of quantum mechanics to solve some problems much more efficiently than conventional computers. Quantum dots, discussed above as a marker for DNA diagnostics, are also of interest as a possible component of quantum computers.
Meanwhile, new methods for the synthesis of semiconductor nanowires are being explored as an efficient way to fabricate nanosensors for chemical detection. Rather than quickly supplanting the highly developed and still rapidly advancing silicon technology, these exploratory devices are more likely to find initial success in new markets and product niches not already well-served by the current technology.
Sensors for industrial process control, chemical and biological hazard detection, environmental monitoring, and a wide variety of scientific instruments may be the market niches in which nanodevices become established in the next few years.
As efforts in the various areas of nanoscale science and technology continue to grow, it is certain that many new materials, properties, and applications will be discovered. Research in areas related to nanofabrication is needed to develop manufacturing techniques, in particular, a synergy of top-down with bottom-up processes. Such manufacturing techniques would combine the best aspects of top-down processes, such as microlithography, with those of bottom-up processes based on self-assembly and self-organization.
Additionally, such new processes would allow the fabrication of highly integrated two- and three-dimensional devices and structures to form diverse molecular and nanoscale components. They would allow many of the new and promising nanostructures, such as carbon nanotubes, organic molecular electronic components, and quantum dots, to be rapidly assembled into more complex circuitry to form useful logic and memory devices.
Such new devices would have computational performance characteristics and data storage capacities many orders of magnitude higher than present devices and would come in even smaller packages.
Nanomaterials and their performance properties will also continue to improve. Thus, even better and cheaper nanopowders, nanoparticles, and nanocomposites should be available for more widespread applications. Another important application for future nanomaterials will be as highly selective and efficient catalysts for chemical and energy conversion processes. This will be important economically not only for energy and chemical production but also for conservation and environmental applications.
Thus, nanomaterial-based catalysis may play an important role in photoconversion devices, fuel cell devices, bioconversion energy and bioprocessing food and agriculture systems, and waste and pollution control systems.
Nanoscale science and technology could have a continuing impact on biomedical areas such as therapeutics, diagnostic devices, and biocompatible materials for implants and prostheses. There will continue to be opportunities for the use of nanomaterials in drug delivery systems.
Combining the new nanosensors with nanoelectronic components should lead to a further reduction in size and improved performance for many diagnostic devices and systems.
Ultimately, it may be possible to make implantable, in vivo diagnostic and monitoring devices that approach the size of cells. New biocompatible nanomaterials and nanomechanical components should lead to the creation of new materials and components for implants, artificial organs, and greatly improved mechanical, visual, auditory, and other prosthetic devices. Exciting predictions aside, these advances will not be realized without considerable research and development.
For example, the present state of nanodevices and nanotechnology resembles that of semiconductor and electronics technology in , when the first point contact transistor was realized, ushering in the Information Age, which blossomed only in the s. We can learn from the past of the semiconductor industry that the invention of individual manufacturable and reliable devices does not immediately unleash the power of technology—that happens only when the individual devices have low fabrication costs, when they are connected together into an organized network, when the network can be connected to the outside world, and when it can be programmed and controlled to perform a certain function.
The full power of the transistor was not really unleashed until the invention of the integrated circuit, with the reliable processing techniques that produce numerous uniform devices and connect them across a large wafer, and the computerized design, wafer-scale packaging, and interconnection. Similarly, it will require an era of spectacular advances in the development of processes to integrate nanoscale components into devices, both with other nanoscale components and with microscale and larger components, accompanied by the ability to do so reliably at low cost.
New techniques for manufacturing massively parallel and fault-tolerant devices will have to be invented. Since nanoscale technology spans a much broader range of scientific disciplines and potential applications than does solid state electronics, its societal impact may be many times greater than that of the microelectronics and computing revolution.
Nanoscale science and technology, often referred to as "nanoscience" or "nanotechnology," are science and engineering enabled by our relatively new ability to manipulate and characterize matter at the level of single atoms and small groups of atoms. This capability is the result of many developments in the last two decades of the 20th century, including inventions of scientific instruments like the scanning tunneling microscope.
Using such tools, scientists and engineers have begun controlling the structure and properties of materials and systems at the scale of 10? Scientists and engineers anticipate that nanoscale work will enable the development of materials and systems with dramatic new properties relevant to virtually every sector of the economy, such as medicine, telecommunications, and computers, and to areas of national interest such as homeland security.
Indeed, early products based on nanoscale technology have already found their way into the marketplace and into defense applications. In , as the tremendous scientific and economic potential of nanoscale science and technology was beginning to be recognized, a federal interagency working group formed to consider creation of a national nanotechnology initiative NNI.
The Committee for the Review of the National Nanotechnology Initiative was formed by the NRC and asked to consider topics such as the current research portfolio of the NNI, the suitability of federal investments, and interagency coordination efforts in this area. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.
Coyopol et al. Singh and S. The production of reactive oxygen species under the light irradiation of two different types of TiO 2 nanocrystals has been studied by L. Fruk et al. The paper on biomineralization processes by S.
Sprio et al. Finally, let us present an application using nanoparticles; a passive capacitor sensor using SnO 2 nanoparticles is presented by M.
Agarwal et al. As the reader may realize, the papers that conform this issue are connected not only by the nature of the systems that are being investigated, and by the techniques used for synthesis and measurement, but also for the emphasis on size effects on the properties of their subjects of study.
We believe that we are living in an exciting age where these size dependencies offer both challenges and opportunities, and that, if we take the appropriate approach, this will give us more room for discoveries and applications, even more than the plenty of room that Feynman was thinking on.
This is an open access article distributed under the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Article of the Year Award: Outstanding research contributions of , as selected by our Chief Editors. Read the winning articles. Journal overview. Special Issues. Article Sections On this page Copyright.
Received 06 Dec Accepted 06 Dec Published 30 Dec More related articles. Reference points involve quantitative measurements. Quantitative measurements are absolute. If the disturbance is negligible, the object is large in an absolute sense; a nonnegligible disturbance means an object is small. Absolute size does not involve comparisons of one object to another.
Relative size is determined by comparing one object to another object; an object is large or small in comparison to another object. A relative measurement may involve comparing a rock to the palm of your hand. If the rock fits inside the hand, it would be considered small. If your hand could rest upon the rock, it would be considered large. Many students can make measurements that involve relative size; however, they may lack accuracy in making absolute or quantitative measurements.
Scale can be defined as an ordered reference standard such as a scale of 1 to Objects at the micro-scale can range in size from. The nanoscale, which is the scale below the micro scale, exists in the range of 1 nm to nm or range from 10 -9 to 10 -7 meters.
To be considered an object at the nanoscale at least one dimension of the object must fit within the nano-scale range this is, one dimension must be less than nm.
A DNA molecule is a good example of an object with one dimension in the nanoscale range. Although a single DNA molecule can be up to 5cm long it is only 2nm wide. Scientific notation is useful for describing objects at the nano-scale; scientific notation allows us to relate the size and scale of objects to well known metric units without using long strings of zeros as placeholders.
To use scientific notation, one must understand that negative powers of ten are the reciprocal of the powers of ten. When working with substances smaller than one and greater than one the powers of ten become useful.
Addressing objects based on varying scales helps one conceptualize how large or small an object really is. Use of scientific notation and metric units in science can help clarify size as it relates to scale.
Strength is the amount of load an object can sustain before it breaks. The larger an object is the number of imperfections it has can increase.
The more imperfections an object has the more weak spots it may have. Very small objects tend to have insensitivity to imperfections and are therefore stronger. Carbon nanotubes are very tiny and very strong. The size of these very tiny structures accounts for their increased strength.
Movies often depict gigantic monsters that have extraordinary strength. The gigantic beast is often depicted as a fast moving building wielding creatures.
In reality, they would not be able to overcome the affects of size. In truth, King Kong's strength would be diminished because of his size. First, he would not be as active as portrayed because of his size. Second, the strength of a bone is proportional to its cross-sectional area. This means King Kong's bone structure could only support a maximum amount of mechanical force before it would break. The actual load a bone can withstand is proportional to the mass of the object.
The hero in "The Incredible Shrinking Man was about an inch tall. In the movie, he was depicted as struggling to lift a needle. In reality, he would have been able to wield the needle around without any problem.
His muscle strength would have increased 70 fold. Smaller animals are proportionally stronger because the forces their muscles produce are proportional to the cross-sectional area.
Their weight is proportional to its volume. Surface area and size change at disproportional rates when one dimension's length at a given scale changes. As size decreases the surface area increases. For example, a packet of sugar, which has many small particles of sugar, would dissolve in a solution faster than a sugar cube, or large particle of sugar, because the packet of sugar particles has a greater surface area than the cube of sugar.
Surface area causes changes in the reaction time of a substance. The greater the surface to volume ration is as it relates to a reacting substance the faster the reaction time. The amount of exposed surface area increases drastically at the nanoscale level, which is the reason the reaction times for chemical reactions increase. Substances at the nanoscale level have a greater surface-to-volume ratio, which causes them to react very quickly. Small particles have a greater percentage of atoms on their surface, which accounts for the increased surface to volume ratio.
Properties are the characteristics that determine how a substance behaves, functions, or appear. Size dependent properties can be categorized as size-dominated or surface-dominated. Electrical properties can change at the nanoscale. Some materials that are conductors in bulk form may become semiconductors or poor conductors at the nanoscale.
Some materials that were semiconductors may become conductors or superconductors. The confinement of electrons results in the electrical properties that occur at the nanoscale. Optical properties are also size dependent. Electrons cannot move about as freely at the nanoscale and become restricted. The confinement of the electrons causes them to react to light differently.
Gold for example will appear gold at the macro scale in bulk form. However when it occurs as nanosized particles its color is red. Nanosized zinc oxide particles will not scatter visible light, which causes sun block to appear transparent. Large zinc oxide particles used for sun block scatter visible light and appear white.
Quantum dots change in their optical appearance as the size of the particles decrease creating different colors. The second category of surface dominated properties involves properties controlled by their surface area. Melting point, rate of reaction, capillary action, and adhesion are properties that are controlled by their surface area.
Gold provides an example of how melting points of a material can change with size. As the size reduces to about 2 nm the melting point decreases to about half of the melting point at the macro scales level. Gold will no longer conduct electricity when it becomes less than 10nm. The instructional format for my school is a modified block schedule. Students attend all seven periods on Mondays and follow an odd even block schedule Tuesday through Friday.
Monday class periods are 55 minutes and block classes are ninety minutes. The instructional format is the three- part lesson with an opening, work period and closing. The bulk of the ninety- minute period block is the work period. Multiple strategies will be utilized for class periods to ensure effective delivery of content and the desired learning outcomes.
Mobile wireless labs will be utilized throughout the unit for students to experience videos and interactive activities related to size and scale. Students will have an opportunity to view objects at the macro scale to the nanoscale using pre-assigned websites and interactive games.
The technology approach will help students conceptualize and visualize objects in the various worlds of size. Students will work with proximity partners to complete a think share activity. The pair will discuss their topic and use critical thinking skills to review and learn key concepts. Each pair will have to discuss and relate information they have learned to questions or activities provided on an assigned topic from the unit. Students will conduct independent and group labs.
Students will have an opportunity to see how surface area, adhesion, magnetisms and physical arrangement of objects change with size. Students will create various types of graphic organizers such as foldables, flip charts, KWL's, and vocabulary maps to review, learn, and understand concepts taught. Students will use various graphic organizers to help them understand complex ideas and organize the information so they can use them at their individual levels of need. Student groups will consist of students from varying levels so they can learn from each other.
Each group will have to work together to accomplish a common task or produce a specific product or to reach a given outcome. The teacher will function as a facilitator to ensure groups stay on task and meet the goals of the group. Students will be given a list of pre-approved books to choose from that relate to size, scale and nanotechnology.
Each student will select one book to read to help him or her meet the book campaign challenge for English Language Arts. Students will also read printed portions from "Prey". Each student will complete a Read for Points activity sheet that explains their feelings about both their book and the reading from "The Prey" and how they relate to the unit.
Students will explain how their book affects their thoughts on nanotechnology's impact on today's society. Pre-Assessments will assess what the students already know about size, powers of ten, and scale. Responses from pre-assessments will help fine tune lessons so they are more appropriate for each group being taught.
Students will range from general classes to gifted and talented classes. This method allows for differentiation of lessons to meet the needs of the participating students. Post assessments will provide information to determine if the desired goals and objectives for the unit were met. Posttest will also determine if some students still need additional help in the form of remediation or individual tutoring.
Prior to the introduction of the unit students will have learned about the structure of atoms. They will use this knowledge to help them understand size and the properties of matter.
A pre-assessment will be given entitled " Fact or Fiction Extreme Size Card" from the book Extreme Science: From Nano to Galactic to determine what students know, understand, and believe about size and scale. The pre-assessment will help to uncover any misconceptions students may have about size and scale so these areas can be addressed as the unit is taught. Once the unit opener is complete, a discussion and review of the fact sheet answers will occur.
The activity will use the three-part lesson format. The opening activity entitled "How Small are Atoms" will connect to student's prior knowledge of atoms and introduce the concept of nano scale and atomic scale objects. The activity requires students to cut a strip of paper in half and discard one-half of their remaining strips each time they fold the paper to try and achieve thirty-one cuts.
Students quickly discover as they fold and cut their sheet that each fold makes it harder to cut the paper. Most students will make 10 cuts before they can no longer cut the strip.
The activity gives students a good visual picture of how small a nano meter is. The Work period will start the second part of the lesson.
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