A5017529828- Carbon Nanotubes in Composites
- Medical Imaging Techniques and Applications
- Advanced X-ray and CT Imaging
- Digital Radiography and Breast Imaging
- Graphene research and applications
- Radiation Therapy and Dosimetry
- Advanced Radiotherapy Techniques
- Fullerene Chemistry and Applications
- Molecular Communication and Nanonetworks
- Nanotechnology research and applications
- Boron and Carbon Nanomaterials Research
- Advanced Electron Microscopy Techniques and Applications
- Radiation Dose and Imaging
- Diamond and Carbon-based Materials Research
- Dental Radiography and Imaging
- Advanced MRI Techniques and Applications
- Force Microscopy Techniques and Applications
- Atomic and Subatomic Physics Research
- Advancements in Battery Materials
- Mechanical and Optical Resonators
- AI in cancer detection
- Ion-surface interactions and analysis
- Advanced X-ray Imaging Techniques
- High-pressure geophysics and materials
- Nanowire Synthesis and Applications
University of North Carolina at Chapel Hill
2015-2024
Uppsala University
2024
Applied Physical Sciences (United States)
2014-2022
Uppsala University Hospital
2022
Colorado State University
2021
UNC/NCSU Joint Department of Biomedical Engineering
2018
UNC Lineberger Comprehensive Cancer Center
2008-2017
Rensselaer Polytechnic Institute
2017
Triangle
2014
Xintek (United States)
2005-2014
We report a method to fabricate polymer-based composites with aligned carbon nanotubes, and procedure determine the nanotube orientation degree of alignment. The were fabricated by casting suspension nanotubes in solution thermoplastic polymer chloroform. They uniaxially stretched at 100 °C found remain elongated after removal load room temperature. alignment determined x-ray diffraction. dispersion also studied transmission electron microscopy.
The fullerene C(60) can be converted into two different structures by high pressure and temperature. They are metastable revert to pristine on reheating 300 degrees C at ambient pressure. For synthesis temperatures between 400 pressures of 5 gigapascals, a nominal face-centered-cubic structure is produced with lattice parameter a(o) = 13.6 angstroms. When treated 500 800 the same pressure, transforms rhombohedral hexagonal parameters 9.22 angstroms c(o) 24.6 intermolecular distance small...
We observe that field emitters made from carbon nanotubes exhibit excellent macroscopic emission properties; they can operate at a very large current density, as high 4 A/cm2. At electric fields low 4–7 V/μm, emit technologically useful densities of 10 mA/cm2. show the originates nanotube ends with characteristic structured ring pattern. The characteristics and durability cold cathodes offer promising applications for vacuum microelectronic devices.
Uniform films of well-aligned carbon nanotubes have been grown using microwave plasma-enhanced chemical vapor deposition. It is shown that can be on contoured surfaces and aligned in a direction always perpendicular to the local substrate surface. The alignment primarily induced by electrical self-bias field imposed surface from plasma environment. found switching source off effectively turns mechanism off, leading smooth transition between plasma-grown straight thermally “curly” nanotubes....
The nucleation and growth of aligned multiwall carbon nanotubes by microwave plasma-enhanced chemical vapor deposition have been studied. nucleate grow from catalytic cobalt islands on a silicon substrate surface, with both their diameter length dependent the size islands. Electron microscopy reveals that via “base growth” mechanism. initially at very rapid constant rate (∼100 nm/s) decreases sharply after catalyst Co particles become fully encapsulated nanotubes. We propose detailed model...
Previous high-resolution electron microscopy (HREM) observations of the carbon nanotubes have led to a "Russian doll" structural model that is based on hollow concentric cylinders capped at both ends. The structures and particles were characterized here by bulk physical chemical property measurements. individual nanostructure as compressible graphite in c axis, such nanostructures can be intercalated with potassium rubidium, leading saturation composition "MC(8)." These results are counter...
X-ray radiation is widely used in medical and industrial applications. The basic design of the x-ray tube has not changed significantly last century. In this paper, we demonstrate that diagnostic can be generated using a carbon nanotube (CNT)-based field-emission cathode. device readily produce both continuous pulsed x-rays with programmable wave form repetition rate. A total emission current 28 mA was obtained from 0.2 cm2 area CNT intensity sufficient to image human extremity at 14 kVp 180...
The electronic structures and the work functions of pristine Cs-intercalated single-walled carbon nanotube bundles were investigated using ultraviolet photoemission spectroscopy. valence bands considerably altered from those graphite. A spectral shift to higher binding energy side was observed in sample. function found be 4.8 eV, which is 0.1–0.2 eV larger than that drastic decrease about 2.4
The effects of structure and morphology on lithium storage in single-wall carbon nanotube (SWNT) bundles were studied by electrochemistry nuclear magnetic resonance techniques. SWNTs chemically etched to variable lengths intercalated with Li. reversible Li capacity increased from LiC(6) close-end LiC(3) after etching, which is twice the value observed graphite. All nanotubes became metallic upon intercalation Li, density states at Fermi level increasing concentration. enhanced attributed...
In this Account, we summarize some of our recent studies on the materials properties carbon nanotubes (CNTs). The focus is single-wall (SWNTs). We describe experiments synthesis SWNTs with controlled molecular structures and assembly functional macroscopic structures. addition, present results electron field emission CNT cathodes.
The first systematic study on alloy formation well-defined nanostructured materialshas been conducted by these authors. Nanostructured silicon and germanium materials were reacted with lithium metal solid-state chemistry electrochemical methods, in which nanocrystalline Si (unlike bulk material) forms Li–Si alloys already at room temperature. Li–Si(Ge) have interesting properties, make them attractive as anode material batteries.
Nanoscale coordination polymers (NCPs), prepared with metal ions and an iodinated ligand, were synthesized using reverse-phase microemulsion techniques rapid precipitation procedures. The NCPs carry high payloads of iodine (ca. 63 wt %) have potential applications as a new class contrast agents for computed tomography (CT), demonstrated by phantom studies (see figure). Detailed facts importance to specialist readers are published "Supporting Information". Such documents peer-reviewed, but...
X-ray diffraction and diamond anvil techniques were used to measure the isothermal compressibility of K 3 C 60 Rb , superconducting, binary alkali-metal intercalation compounds solid buckminsterfullerene. These results, combined with pressure dependence superconducting onset temperature T c measured by other groups, establish a universal first-order relation between lattice parameter over broad range, 13.9 14.5 angstroms. A small second-order intercalate-specific effect was observed that...
We report a field emission x-ray source that can generate scanning beam to image an object from multiple projection angles without mechanical motion. The key component of the device is gated carbon nanotube cathode with array electron emitting pixels are individually addressable via metal–oxide–semiconductor effect transistor-based electronic circuit. characteristics this measured and its imaging capability demonstrated. potentially lead fast data acquisition rate for laminography...
Carbon nanotube (CNT) field emitters are now being evaluated for a wide range of vacuum electronic applications. However, problems including short lifetime at high current density, instability under voltage, poor emission uniformity, and pixel-to-pixel inconsistency still major obstacles device We developed an electrophoretic process to fabricate composite CNT films with controlled orientation surface enhanced adhesion. The cathodes have significantly macroscopic density long-term stability...
Nanoscale metal–organic frameworks (NMOFs) of the UiO-66 structure containing high Zr (37 wt%) and Hf (57 content were synthesized characterized, their potential as contrast agents for X-ray computed tomography (CT) imaging was evaluated. Hf-NMOFs different sizes coated with silica poly(ethylene glycol) (PEG) to enhance biocompatibility, used in vivo CT mice, showing increased attenuation liver spleen.
Single-crystalline lanthanum hexaboride (LaB6) nanowires show excellent electric-field-induced electron emission following the Fowler–Nordheim scheme. The LaB6 grow in <001> crystallographic direction (see Figure) with diameters of about 20 nm. An current 30 nA from a single nanowire, corresponding to density 5 × 105 A cm–2, has been obtained.
Microcomputed tomography is now widely used for in vivo small animal imaging cancer studies. Achieving high quality of live objects requires the x-ray source to have both spatial and temporal resolutions. Preliminary studies shown that carbon nanotube (CNT) based field emission has significant intrinsic advantages over conventional thermionic tube including better resolution programmability. Here we report design characterization a CNT also affords resolution. The device uses modified...
Purpose: The purpose of this study is to investigate the feasibility increasing system spatial resolution and scanning speed Hologic Selenia Dimensions digital breast tomosynthesis (DBT) scanner by replacing rotating mammography x‐ray tube with a specially designed carbon nanotube (CNT) source array, which generates all projection images needed for reconstruction electronically activating individual sources without any mechanical motion. stationary (s‐DBT) design aims (i) increase...