Chinese researchers have developed a more stable and more powerful field emission device for two sided liquid crystal displays using carbon nanotubes, earning U.S Patent 7,615,919 for Tsinghua University (Beijing, CN) and Hon Hai Precision Industry Co., Ltd. (Tu-Cheng, Taipei Hsien, TW)
Field emission devices are based on emission of electrons in a vacuum. Electrons are emitted from micron-sized tips in a strong electric field, and the electrons are accelerated and collide with a fluorescent material. The fluorescent material then emits visible light. Field emission devices are thin, light weight, and provide high levels of brightness.
Conventionally, a material of the tips is selected from the group consisting of molybdenum (Mo) and silicon (Si). With the development of nano-technology, carbon nanotube (CNT) is also used in the tips of the field emission devices. However, the typical working voltage of such field emission devices is about 10,000 volts, which can easily generate enough static force to break the CNTs. As a result, performance of these field emission devices is unstable.
A more stable field emission device was developed by Yuan-Chao Yang, Jie Tang, Liang Liu, and Shou-Shan Fan. Their FET device includes a sealed container with a first light-permeable portion and an opposite second light-permeable portion. A first phosphor layer is formed on the first light-permeable portion. A first light-permeable anode is formed on the first phosphor layer. A second phosphor layer is formed on the second light-permeable portion. A second light-permeable anode is formed on the second phosphor layer. A shielding barrel is disposed within the container and electrically connected to at least one cathode electrode. One opening of the shielding barrel faces towards the first light-permeable portion and the other opening faces towards the second light-permeable portion. The shielding barrel has an inner surface. A conductive nano material layer is formed on the inner surface of the shielding barrel.
The first and the second light-permeable anodes are metal films with good electric conductivity. The anodes are aluminum films. The shielding barrel is a cylinder with a central axis perpendicular to the first and the second light-permeable portions. It can be understood that other shapes of the shielding barrel can be selected according to the shape of the sealed container.
The conductive nano-material layer comprises a material selected from the group consisting of carbon nanotubes, carbon nano-sticks, carbon nano-yarns, Buckminster-fullerenes (C60), and carbon nano-particles. The conductive nano-material layer can also be made of a material selected from the group consisting of nanotubes, nano-sticks, nano-yarns, nano-particles of conductive metal and semiconductors. The conductive nano-material layer consists of carbon nanotubes. Firstly, the nano slurry is spread on the inner surface of the shielding barrel and solidified. Then the conductive nano-material is scrubbed with a rubber to expose ends of the carbon nano tubes so that the conductivity of the shielding barrel can be enhanced. Distance between edge (e.g., top end) of the conductive nano-material layer and edge (e.g., top end) of the shielding barrel determines shielding effect of the shielding barrel.
In order to maintain the vacuum of the inner space of the sealed container, a getter may be arranged therein to absorb residual gas inside the sealed container. The getter should preferably be arranged on an inner surface of the sealed container around the electrodes. The getter may be evaporable getter introduced using high frequency heating. The getter also can be non-evaporable getter. It must be ensured that the getter does not attach to the light-permeable anodes in order to avoid short circuits between the light-permeable anode and the electrodes.
The sealed container further includes an air vent. The air vent connects a vacuum pump to vacuum the sealed container before packaging sealing the container.
In operation, when putting a voltage over the electrodes and the light-permeable anodes Electrons will emanate from two openings of the shielding barrel. The electrons move towards and transmit through the first and the second light-permeable anodes. When the electrons hit the first and second phosphor layers visible lights will be emitted. One part of the lights will transmit through the first and the second light-permeable portions, and the other part of the lights will be reflected by the first and the second light-permeable anodes, and spread out of the light-permeable portions. Tubes can be arranged together to use for lighting and two-sided displaying. Because of the shielding effect of the shielding barrel, the field emission device can operate with greater stability at higher voltages.
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Showing posts with label carbon nanotube alloy. Show all posts
Carbon Nanotube FET Device Enables Two Sided Displays
11/10/09 |
Labels:
615,
919,
carbon nanotube alloy,
FET device,
Hon Hai Precision Industry,
Tsinghua University,
two sided display,
U.S. Patent 7
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Carbon Nanotubes and Boron Nitride Nanotubes Explode Cancer Cells
11/2/09 |
Labels:
Boron Neutron-Capture Therapy,
boron nitride nanotube,
cancer imaging,
cancer therapy,
cancer treatment,
carbon nanotube alloy,
medical imaging,
U.S. Patent 7608240
University of Arkansas scientists have developed a novel approach to cancer therapy and diagnostics that utilizes nanotubes and other similar nanostructures as both an indirect source of radiation therapy, and as delivery vehicles for other types of radio- and chemo-therapeutic materials, as well as imaging agents for diagnostic purposes. The Board of Trustees of the University of Arkansas (Little Rock, AR) received U.S. Patent 7,608,240 for their discovery.
According to inventors Dan A. Buzatu, Jon G Wilkes, Dwight Miller, Jerry A. Darsey, Tom Heinze, Alex Biris, Richard Berger and Mark Diggs, some embodiments involve the use of boron nitride (BN) nanostructures in boron neutron capture therapy (BNCT). Antibody species are attached to the BN nanostructures to enable them to target tumors when administered to a mammalian subject. These tumor-targeting species are referred to as BN nanostructure-antibody composite species. Once such composite species are in the proximity of a tumor, they can be activated with transdermal neutrons. Once activated, the boron atoms emit alpha particles that are capable of destroying cancerous cells.
Carbon nanostructures (e.g., carbon nanotubes) can be used to deliver radiation to a target region. Radioactive isotopes are attached to a carbon nanostructure to which one or more antibody species are attached. These radioactive-laden carbon nanotube-antibody species can then be employed to selectively target tumors when administered to a mammalian subject.
In other embodiments, tumor cloned IgGs are used to carry nanocontainers (e.g., single-wall carbon nanotubes), bound to the IgGs, to the tumor sites. Ultrasonic waves are then used to explode the carbon nanotubes in the proximity of the tumor. Ultrasound is capable of penetrating deep through tissue without tissue damage because the frequency of the waves can be adjusted to be absorbed only by the target, here carbon or other nanostructures. The technique can also be used to deliver effective chemotherapeutic substances, toxic to a tumor, encapsulated inside the nanostructures.
In all of the above-mentioned embodiments, the BN nanostructures, the carbon nanostructures, and the nanocontainers (nanovessels), can all be encapsulated with a bio-polymer. In some of these embodiments, the antibody species is attached to the nanostructure/nanocontainer through the bio-polymer. Encapsulating materials such as these with bio-polymers can circumvent the need to attach the antibody species (e.g., IgG), and it can reduce potential nanoparticle toxicity and/or enhance the solubility of the IgG-nanostructure complexes in biological fluids.
Tumor cloned IgGs are used to carry nanocontainers, probably single walled nanovessels (e.g., single-wall carbon nanotubes), covalently bound to the IgGs, to the tumor sites. Ultrasound waves with a frequency that is absorbed by the nanotubes (.about.20-40 KHz), are used to explode the carbon nanotubes in the proximity of the tumor. Such use of ultrasound waves to explode carbon nanotubes is analogous to the ultrasound method that is used to destroy kidney stones. Ultrasound is capable of penetrating deep through tissue without tissue damage because the frequency of the waves can be adjusted to be absorbed only by the target, here carbon or other nanostructures. The technique can also be used to deliver effective chemotherapeutic substances, toxic to a tumor, encapsulated inside the nanostructures. Some examples of toxic materials are inorganic substances such as arsenic oxide (AsO), cadmium, cisplatin, etc., as well as organic chemotherapeutic agents such as vinblastine/vincristine, ifosfamide, etoposide, etc.
Unfortunately, while these chemotherapeutic agents are very effective at destroying cells through various mechanisms, they do not discriminate between healthy cells and tumor cells. This can result in the severe side effects that are associated with conventional chemotherapy. However, by using the IgGs to deliver drug-filled nanostructures directly to a tumor, then using ultrasonic waves to break open the nanostructures and release the tumor-toxic substances at the site of the tumor, many of the side effects can be reduced or eliminated. In each case, the IgGs are used to carry nanostructures specifically to a tumor, and ultrasonic waves are used to either explode or break open the nanotubes, destroying the tumor.
Boron Neutron-Capture Therapy
Boron Neutron Capture Therapy (BNCT) is an experimental approach to cancer treatment that is based on a dual-step technique: accumulation of a boron-containing compound within a tumor and treatment with a beam of low-energy neutrons directed at the boron-containing tumor. The nuclei of the boron atoms capture the neutrons and split into two highly charged particles (alpha particle and lithium ion) that have very short path lengths, approximating one cell diameter. These charged particles release sufficient energy locally to kill any tumor cells that contain high concentrations of boron. Over the past nine years, the United States Dept. of Energy (DOE) has supported a nationwide research program to develop BNCT for clinical use.
Catching Neutrons to Combat Cancer
Subjecting boron atoms to low-energy neutron radiation (thermal neutrons) causes the boron nuclei to disintegrate into alpha particles and lithium isotopes with a kinetic energy of 2.5 MeV. When this disintegration occurs in malignant cells, the energy generated is sufficient to destroy them without damaging the neighboring cells, since the range of the particles is only about 10 microns. In such BNCT, it has been estimated that it takes 109 boron atoms per tumor cell for a therapeutic dose. As each tumor cell has about 106 effective antigenic sites that can act as targets, the number of boron atoms required per carrier has been calculated to be 103. Thus, 1,000 boron atoms are needed per antibody molecule for effective treatment. However, this has been heretofore impractical because when this many small carbo-borane molecules are attached to the antibody molecule, it loses its tumor-specific targeting ability.
Other boron-containing compounds (e.g., porphyrins containing boron) currently being used in such therapies, however, generally comprise only a very small amount of boron. It would be useful if a molecular species with a higher percentage of boron (wt. % relative to the overall molecular weight of the molecule) could be used in BNCT.
Boron Nitride Nanotubes
Boron nitride (BN) nanotubes have been synthesized and shown to behave in many ways like their carbon nanotube. For example, they show the same propensity to agglomerate into bundles held together by van der Waals attractive forces. Furthermore, they have been observed to exist as single- or multi-walled varieties. There are notable differences, however, namely that they are insulating and possess a constant bandgap of 5 eV irrespective of tube diameter, number of walls, and chirality.
Use of such BN nanotubes (BNnt) in BNCT would be very advantageous on a percent boron basis--if BN nanotubes could be made therapeutically deliverable. Additionally, other types of nanotubes and nanostructures could be made to serve as delivery vehicles in cancer treatments and in diagnostic imaging. A related advantage is the ability to attach BN nanostructures to an IgG or other targeting biomolecule at only one or a few locations, so that the attached therapeutic atoms do not cover or interfere with the target molecule's receptor and thus compromise specificity.
According to inventors Dan A. Buzatu, Jon G Wilkes, Dwight Miller, Jerry A. Darsey, Tom Heinze, Alex Biris, Richard Berger and Mark Diggs, some embodiments involve the use of boron nitride (BN) nanostructures in boron neutron capture therapy (BNCT). Antibody species are attached to the BN nanostructures to enable them to target tumors when administered to a mammalian subject. These tumor-targeting species are referred to as BN nanostructure-antibody composite species. Once such composite species are in the proximity of a tumor, they can be activated with transdermal neutrons. Once activated, the boron atoms emit alpha particles that are capable of destroying cancerous cells.
Carbon nanostructures (e.g., carbon nanotubes) can be used to deliver radiation to a target region. Radioactive isotopes are attached to a carbon nanostructure to which one or more antibody species are attached. These radioactive-laden carbon nanotube-antibody species can then be employed to selectively target tumors when administered to a mammalian subject.
In other embodiments, tumor cloned IgGs are used to carry nanocontainers (e.g., single-wall carbon nanotubes), bound to the IgGs, to the tumor sites. Ultrasonic waves are then used to explode the carbon nanotubes in the proximity of the tumor. Ultrasound is capable of penetrating deep through tissue without tissue damage because the frequency of the waves can be adjusted to be absorbed only by the target, here carbon or other nanostructures. The technique can also be used to deliver effective chemotherapeutic substances, toxic to a tumor, encapsulated inside the nanostructures.
In all of the above-mentioned embodiments, the BN nanostructures, the carbon nanostructures, and the nanocontainers (nanovessels), can all be encapsulated with a bio-polymer. In some of these embodiments, the antibody species is attached to the nanostructure/nanocontainer through the bio-polymer. Encapsulating materials such as these with bio-polymers can circumvent the need to attach the antibody species (e.g., IgG), and it can reduce potential nanoparticle toxicity and/or enhance the solubility of the IgG-nanostructure complexes in biological fluids.
Tumor cloned IgGs are used to carry nanocontainers, probably single walled nanovessels (e.g., single-wall carbon nanotubes), covalently bound to the IgGs, to the tumor sites. Ultrasound waves with a frequency that is absorbed by the nanotubes (.about.20-40 KHz), are used to explode the carbon nanotubes in the proximity of the tumor. Such use of ultrasound waves to explode carbon nanotubes is analogous to the ultrasound method that is used to destroy kidney stones. Ultrasound is capable of penetrating deep through tissue without tissue damage because the frequency of the waves can be adjusted to be absorbed only by the target, here carbon or other nanostructures. The technique can also be used to deliver effective chemotherapeutic substances, toxic to a tumor, encapsulated inside the nanostructures. Some examples of toxic materials are inorganic substances such as arsenic oxide (AsO), cadmium, cisplatin, etc., as well as organic chemotherapeutic agents such as vinblastine/vincristine, ifosfamide, etoposide, etc.
Unfortunately, while these chemotherapeutic agents are very effective at destroying cells through various mechanisms, they do not discriminate between healthy cells and tumor cells. This can result in the severe side effects that are associated with conventional chemotherapy. However, by using the IgGs to deliver drug-filled nanostructures directly to a tumor, then using ultrasonic waves to break open the nanostructures and release the tumor-toxic substances at the site of the tumor, many of the side effects can be reduced or eliminated. In each case, the IgGs are used to carry nanostructures specifically to a tumor, and ultrasonic waves are used to either explode or break open the nanotubes, destroying the tumor.
Boron Neutron-Capture Therapy
Boron Neutron Capture Therapy (BNCT) is an experimental approach to cancer treatment that is based on a dual-step technique: accumulation of a boron-containing compound within a tumor and treatment with a beam of low-energy neutrons directed at the boron-containing tumor. The nuclei of the boron atoms capture the neutrons and split into two highly charged particles (alpha particle and lithium ion) that have very short path lengths, approximating one cell diameter. These charged particles release sufficient energy locally to kill any tumor cells that contain high concentrations of boron. Over the past nine years, the United States Dept. of Energy (DOE) has supported a nationwide research program to develop BNCT for clinical use.
Catching Neutrons to Combat Cancer
Subjecting boron atoms to low-energy neutron radiation (thermal neutrons) causes the boron nuclei to disintegrate into alpha particles and lithium isotopes with a kinetic energy of 2.5 MeV. When this disintegration occurs in malignant cells, the energy generated is sufficient to destroy them without damaging the neighboring cells, since the range of the particles is only about 10 microns. In such BNCT, it has been estimated that it takes 109 boron atoms per tumor cell for a therapeutic dose. As each tumor cell has about 106 effective antigenic sites that can act as targets, the number of boron atoms required per carrier has been calculated to be 103. Thus, 1,000 boron atoms are needed per antibody molecule for effective treatment. However, this has been heretofore impractical because when this many small carbo-borane molecules are attached to the antibody molecule, it loses its tumor-specific targeting ability.
Other boron-containing compounds (e.g., porphyrins containing boron) currently being used in such therapies, however, generally comprise only a very small amount of boron. It would be useful if a molecular species with a higher percentage of boron (wt. % relative to the overall molecular weight of the molecule) could be used in BNCT.
Boron Nitride Nanotubes
Boron nitride (BN) nanotubes have been synthesized and shown to behave in many ways like their carbon nanotube. For example, they show the same propensity to agglomerate into bundles held together by van der Waals attractive forces. Furthermore, they have been observed to exist as single- or multi-walled varieties. There are notable differences, however, namely that they are insulating and possess a constant bandgap of 5 eV irrespective of tube diameter, number of walls, and chirality.
Use of such BN nanotubes (BNnt) in BNCT would be very advantageous on a percent boron basis--if BN nanotubes could be made therapeutically deliverable. Additionally, other types of nanotubes and nanostructures could be made to serve as delivery vehicles in cancer treatments and in diagnostic imaging. A related advantage is the ability to attach BN nanostructures to an IgG or other targeting biomolecule at only one or a few locations, so that the attached therapeutic atoms do not cover or interfere with the target molecule's receptor and thus compromise specificity.
Tsinghua University Carbon Nanotube Magnesium Composite Suitable for Aerospace and Auto Use
10/11/09 |
Labels:
carbon nanotube alloy,
Carbon Nanotube Magnesium Composite,
nanotechnology,
Tsinghua University,
U.S. Patent Application 20090127743
Nowadays, various alloys have been developed for special applications. Among these alloys, magnesium alloys have relatively superior mechanical properties, such as low density, good wear resistance, and high elastic modulus. However, the toughness and the strength of the magnesium alloys are not able to meet the increasing needs of the automotive and aerospace industry for tougher and stronger alloys. Tsinghua University scientists created a magnesium-based carbon nanotube composite material that is strong, tough, has a high density, and can be widely used in a variety of fields including the automotive and aerospace industries.
In the magnesium-based composite material, nanoscale reinforcements (e.g. carbon nanotubes and carbon nanofibers) are mixed with the magnesium metal or alloy. The most common methods for making the magnesium-based composite material have been thixomolding and die-casting. However, in die-casting, the magnesium or magnesium alloy is easily oxidized. In thixomolding, the nanoscale reinforcements are added to melted metal or alloy but are prone to aggregate. As such, the nanoscale reinforcements can't be well dispersed.
Tsinghua researchers Kam-Shau Chan, Cheng-Shi Chen, Guang-Liang Sheu, Qing-Chun Du And Wen-Zhen Li developed an apparatus for fabricating a magnesium-based carbon nanotube composite material, in which the problems of aggregation and settling are eliminated or at least alleviated. Tsinghua University’s method includes the steps of: (a) providing a magnesium-based melt and carbon nanotubes, mixing the carbon nanotubes with the magnesium-based melt to achieve a mixture; (b) injecting the mixture into at least one mold to achieve a preform; and (c) extruding the preform to achieve the magnesium-based carbon nanotube composite material.
The mixing device includes a container with a protective gas therein, a stirrer disposed in a center of the container, and a heater (e.g. hot wires) disposed on a outer wall of the container. Quite suitably, the protective gas can, beneficially, be made up of at least one of nitrogen, ammonia, and a noble gas. The heater heats the container to a predetermined temperature in the approximate range from 550 degree C. to 750 degree C. Carbon nanotubes are in the approximate range from 1% to 5% by weight in the alloy. The materials is extruded into performs where it cools quickly enough to prevent settling and aggregation of the carbon nanotubes.
In the extrusion step, the preforms experience a deformation process when extruded from the exit. In the deformation process, different parts of the preforms will be mixed together. The carbon nanotubes are redistributed in the preforms which enhances dispersion uniformity of the carbon nanotubes in the magnesium-based carbon nanotube composite material. The mixing apparatus is detailed in U.S. Patent Application 20090127743. It is one of 47 applications concerning carbon nanotubes filed by Tsinghua University which is among China's leaders in nanotechnology research and development. The University already hold 20 U.S. Patents related to nanotechnology.
In the magnesium-based composite material, nanoscale reinforcements (e.g. carbon nanotubes and carbon nanofibers) are mixed with the magnesium metal or alloy. The most common methods for making the magnesium-based composite material have been thixomolding and die-casting. However, in die-casting, the magnesium or magnesium alloy is easily oxidized. In thixomolding, the nanoscale reinforcements are added to melted metal or alloy but are prone to aggregate. As such, the nanoscale reinforcements can't be well dispersed.
Tsinghua researchers Kam-Shau Chan, Cheng-Shi Chen, Guang-Liang Sheu, Qing-Chun Du And Wen-Zhen Li developed an apparatus for fabricating a magnesium-based carbon nanotube composite material, in which the problems of aggregation and settling are eliminated or at least alleviated. Tsinghua University’s method includes the steps of: (a) providing a magnesium-based melt and carbon nanotubes, mixing the carbon nanotubes with the magnesium-based melt to achieve a mixture; (b) injecting the mixture into at least one mold to achieve a preform; and (c) extruding the preform to achieve the magnesium-based carbon nanotube composite material.
The mixing device includes a container with a protective gas therein, a stirrer disposed in a center of the container, and a heater (e.g. hot wires) disposed on a outer wall of the container. Quite suitably, the protective gas can, beneficially, be made up of at least one of nitrogen, ammonia, and a noble gas. The heater heats the container to a predetermined temperature in the approximate range from 550 degree C. to 750 degree C. Carbon nanotubes are in the approximate range from 1% to 5% by weight in the alloy. The materials is extruded into performs where it cools quickly enough to prevent settling and aggregation of the carbon nanotubes.
In the extrusion step, the preforms experience a deformation process when extruded from the exit. In the deformation process, different parts of the preforms will be mixed together. The carbon nanotubes are redistributed in the preforms which enhances dispersion uniformity of the carbon nanotubes in the magnesium-based carbon nanotube composite material. The mixing apparatus is detailed in U.S. Patent Application 20090127743. It is one of 47 applications concerning carbon nanotubes filed by Tsinghua University which is among China's leaders in nanotechnology research and development. The University already hold 20 U.S. Patents related to nanotechnology.
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