Yuan X Cheng

US Patent:

6969690, Nov 29, 2005

Filed:

Mar 18, 2004

Appl. No.:

10/803639

Inventors:

Otto Z. Zhou - Chapel Hill NC, US
Soojin Oh - Chapel Hill NC, US
Jian Zhang - Carrboro NC, US
Yuan Cheng - Chapel Hill NC, US
Hideo Shimoda - Chapel Hill NC, US

Assignee:

The University of North Carolina at Chapel Hill - Chapil Hill NC

International Classification:

H01L021/469

US Classification:

438787, 438790, 438678

Abstract:

Methods and apparatus are described for patterned deposition of nanostructure-containing materials by self-assembly and related articles. According to an exemplary embodiment self-assembly method for depositing nanostructure-containing materials includes forming a nanostructure-containing material. The nanostructure-containing material is chemically functionalized and dispersed in a liquid medium to form a suspension. At least a portion of a substrate having a surface that can attract the functionalized nanostructure-containing material is brought into contact with the suspension. The substrate is separated from the suspension. The nanostructure-containing material adheres to the portion of the substrate when separated from the suspension. According to another exemplary embodiment, hydrophilic and hydrophobic regions are formed on the surface of the substrate before bringing the substrate into contact with the suspension. The functionalized nanostructure-containing material is hydrophilic and adheres to the hydrophilic region of the substrate when separated from the suspension.

US Patent:

7082182, Jul 25, 2006

Filed:

Aug 20, 2004

Appl. No.:

10/923385

Inventors:

Otto Z. Zhou - Chapel Hill NC, US
Jianping Lu - Chapel Hill NC, US
Yueh Lee - Durham NC, US
Weili Lin - Chapel Hill NC, US
Yuan Cheng - Chapel Hill NC, US
Jian Zhang - Carrboro NC, US

Assignee:

The University of North Carolina at Chapel Hill - Chapel Hill NC

International Classification:

G01N 23/00

US Classification:

378 10, 378122

Abstract:

Computed tomography device comprising an x-ray source and an x-ray detecting unit. The x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator. Each electron emitting unit includes an electron field emitting material. The electron field emitting material includes a nanostructured material or a plurality of nanotubes or a plurality of nanowires. Computed tomography methods are also provided.

US Patent:

7085351, Aug 1, 2006

Filed:

Feb 5, 2003

Appl. No.:

10/358160

Inventors:

Jianping Lu - Chapel Hill NC, US
Otto Zhou - Chapel Hill NC, US
Yuan Cheng - Chapel Hill NC, US

Assignee:

University of North Carolina at Chapel Hill - Chapel Hill NC

International Classification:

H01J 35/32

US Classification:

378122, 3151693

Abstract:

An x-ray generating device includes a field emission cathode formed at least partially from a nanostructure-containing material having an emitted electron current density of at least 4 A/cm. High energy conversion efficiency and compact design are achieved due to easy focusing of cold cathode emitted electrons and dramatic reduction of heating at the anode. In addition, by pulsing the field between the cathode and the gate or anode and focusing the electron beams at different anode materials, pulsed x-ray radiation with varying energy can be generated from a single device. Methods and apparatus for independent control of electron emission current and x-ray energy in x-ray tubes are also provided. The independent control can be accomplished by adjusting the distance between the cathode and anode. The independent control can also be accomplished by adjusting the temperature of the cathode.

US Patent:

7227924, Jun 5, 2007

Filed:

Feb 7, 2005

Appl. No.:

11/051332

Inventors:

Otto Z. Zhou - Chapel Hill NC, US
Yuan Cheng - Chapel Hill NC, US
Jian Zhang - Chapel Hill NC, US
Yueh Lee - Durham NC, US
Jianping Lu - Chapel Hill NC, US
Weili Lin - Chapel Hill NC, US

Assignee:

The University of North Carolina at Chapel Hill - Chapel Hill NC

International Classification:

G01N 23/00

US Classification:

378 10, 378 20

Abstract:

Computed tomography scanning systems and methods using a field emission x-ray source are disclosed. An exemplary micro-computed tomography scanner comprises a micro-focus field emission x-ray source, an x-ray detector, an object stage placed between the x-ray source and the detector, an electronic control system and a computer that control the x-ray radiation and detector data collection, and computer software that reconstructs the three dimension image of the object using a series of projection images collected from different projection angles. Exemplary methods obtain a computed tomography image of an object in oscillatory motion using the micro computed tomography scanner.

US Patent:

8155262, Apr 10, 2012

Filed:

Sep 22, 2006

Appl. No.:

11/526217

Inventors:

Otto Z. Zhou - Chapel Hill NC, US
Jianping Lu - Chapel Hill NC, US
Jian Zhang - Carrboro NC, US
Guang Yang - Carrboro NC, US
Yueh Lee - Durham NC, US
Qi Qiu - Cary NC, US
Yuan Cheng - Chapel Hill NC, US

Assignee:

The University of North Carolina at Chapel Hill - Chapel Hill NC
Xintek, Inc. - Research Triangle Park NC

International Classification:

A61B 6/03

US Classification:

378 4, 378 9, 378 19, 378122, 382131

Abstract:

Methods, systems, and computer program products for multiplexing computed tomography are disclosed. According to one aspect, the subject matter described herein can include illuminating an object with a plurality of x-ray beams from a plurality of viewing angles, wherein each x-ray beam has a distinct waveform; detecting the x-ray intensities of the plurality of pulsed x-ray beams as a function of time, and extracting individual projection image data from the detected x-ray intensities based on the distinct waveforms of the x-ray beams for combining the projection image data to generate three-dimensional tomographic image data of the object.

US Patent:

8447013, May 21, 2013

Filed:

Mar 22, 2011

Appl. No.:

13/069286

Inventors:

Frank Sprenger - Cary NC, US
Moritz Beckmann - Cary NC, US
Yuan Cheng - Cary NC, US
Houman Jafari - Cary NC, US

Assignee:

XinRay Systems Inc - Research Triangle Park NC

International Classification:

H01J 35/00

US Classification:

378122, 378134, 378136

Abstract:

Multibeam field emission x-ray systems and related methods can include cathode elements, an anode assembly spaced from the plurality of cathode elements, and an extraction gate positioned between the plurality of cathode elements and the anode assembly. A potential difference can be applied between the extraction gate and at least one of the cathode elements to cause an emission of electrons from the respective cathode elements. Emission characteristics of the cathode elements can be measured, and the potential difference between the extraction gate and at least one of the cathode elements can be adjusted based on the emission characteristics measured.

US Patent:

20040213378, Oct 28, 2004

Filed:

Apr 24, 2003

Appl. No.:

10/421931

Inventors:

Otto Zhou - Chapel Hill NC, US
Jianping Lu - Chapel Hill NC, US
Yueh Lee - Durham NC, US
Weili Lin - Chapel Hill NC, US
Yuan Cheng - Chapel Hill NC, US
Jian Zhang - Carrboro NC, US

Assignee:

The University of North Carolina at Chapel Hill

International Classification:

H01J035/22

US Classification:

378/122000

Abstract:

Computed tomography device comprising an x-ray source and an x-ray detecting unit. The x-ray source comprises a cathode with a plurality of individually programmable electron emitting units that each emit an electron upon an application of an electric field, an anode target that emits an x-ray upon impact by the emitted electron, and a collimator. Each electron emitting unit includes an electron field emitting material. The electron field emitting material includes a nanostructured material or a plurality of nanotubes or a plurality of nanowires. Computed tomography methods are also provided.

US Patent:

20060274889, Dec 7, 2006

Filed:

May 2, 2006

Appl. No.:

11/415953

Inventors:

Jianping Lu - Chapel Hill NC, US
Otto Zhou - Chapel Hill NC, US
Yuan Cheng - Chapel Hill NC, US

International Classification:

H01J 35/00

US Classification:

378122000

Abstract:

An x-ray generating device includes a field emission cathode formed at least partially from a nanostructure-containing material having an emitted electron current density of at least 4 A/cm. High energy conversion efficiency and compact design are achieved due to easy focusing of cold cathode emitted electrons and dramatic reduction of heating at the anode. In addition, by pulsing the field between the cathode and the gate or anode and focusing the electron beams at different anode materials, pulsed x-ray radiation with varying energy can be generated from a single device. Methods and apparatus for independent control of electron emission current and x-ray energy in x-ray tubes are also provided. The independent control can be accomplished by adjusting the distance between the cathode and anode. The independent control can also be accomplished by adjusting the temperature of the cathode. The independent control can also be accomplished by optical excitation of the cathode. The cathode can include field emissive materials such as carbon nanotubes.