Characterizing uptake of lignin breakdwon products into P. chrysosporium and S. cerevisiae
Abstract not provided.
Publications
Chemical Interference of Quantum Size Controlled Photoelectrochemical Fabrication
Abstract not provided.
Atmospheric solids analysis probe mass spectrometry for the rapid identification of pollens and semi-quantification of flavonoid fingerprints
Rapid communications in mass spectrometry : RCM
RATIONALE: From allergies to plant reproduction, pollens have important impacts on the health of human and plant populations, yet identification of pollen grains remains difficult and time-consuming. Low-volatility flavonoids generated from pollens cannot be easily characterized and quantified with current analytical techniques. METHODS: Here we present the novel use of atmospheric solids analysis probe mass spectrometry (ASAP-MS) for the characterization of flavonoids in pollens. Flavonoid patterns were generated for pollens collected from different plant types (trees and bushes) in addition to bee pollens from distinct geographic regions. Standard flavonoids (kaempferol and rhamnazin) and those produced from pollens were compared and assessed with ASAP-MS using low-energy collision MS/MS. Results for a semi-quantitative method for assessing the amount of a flavonoid in pollens are also presented. RESULTS: Flavonoid patterns for pollen samples were distinct with variability in the number and relative abundance of flavonoids in each sample. Pollens contained 2-5 flavonoids, and all but Kochia scoparia contained kaempferol or kaempferol isomers. We establish this method as a reliable and applicable technique for analyzing low-volatility compounds with minimal sample preparation. Standard curves were generated using 0.2-5 μg of kaempferol; from these experiments, it was estimated that there is approximately 2 mg of kaempferol present in 1 g of P. nigra italica pollen. CONCLUSIONS: Pollens can be characterized with a simple flavonoid pattern rather than analyzing the whole product pattern or the products-temperature profiles. ASAP-MS is a rapid analytical technique that can be used to distinguish between plant pollens and between bee pollens originating from different regions. Copyright © 2016 John Wiley & Sons, Ltd.
Influence of pH on the Quantum-Size-Controlled Photoelectrochemical Etching of Epitaxial InGaN Quantum Dots
Journal of Physical Chemistry C
Illumination by a narrow-band laser has been shown to enable photoelectrochemical (PEC) etching of InGaN thin films into quantum dots with sizes controlled by the laser wavelength. Here, we investigate and elucidate the influence of solution pH on such quantum-size-controlled PEC etch process. We find that although a pH above 5 is often used for PEC etching of GaN-based materials, oxides (In2O3 and/or Ga2O3) form which interfere with quantum dot formation. At pH below 3, however, oxide-free QDs with self-terminated sizes can be successfully realized.
Biodetection using Mass Spectrometry
Abstract not provided.
Deterministic Placement of Fabricated InGaN Quantum Dots in Photonic Structures (invited)
Abstract not provided.
Full Product Pattern Recognition in β-Carotene Thermal Degradation through Ionization Enhancement
Sandia journal manuscript; Not yet accepted for publication
The full product pattern including both volatile and nonvolatile compounds was presented for the first time for β-Carotene thermal degradation at variable temperatures up to 600°C. Solvent-enhanced ionization was used to confirm and distinguish between the dissociation mechanisms that lead to even and odd number mass products.
Lithographically defined three-dimensional graphene scaffolds
Abstract not provided.
Nanophotonic Structures for Extreme Light-Confinement Interaction (invited)
Abstract not provided.
Investigation of Biological Fingerprints Using Atmospheric Solid Analysis Probe Mass Spectrometry (ASAP-MS)
Abstract not provided.
Full product pattern recognition in thermal degradation of β-carotene through ionization enhancement
Abstract not provided.
InGaN Quantum Dot Fabrication using Quantum Size Controlled Photoelectrochemical Etching
Abstract not provided.
Photoelectrochemical etching of epitaxial InGaN thin films: Self-limited kinetics and nanostructuring
Electrochimica Acta
We report here the characteristics of photoelectrochemical (PEC) etching of epitaxial InGaN semiconductor thin films using a narrowband laser with a linewidth less than ∼1 nm. In the initial stages of PEC etching, when the thin film is flat, characteristic voltammogram shapes are observed. At low photo-excitation rates, voltammograms are S-shaped, indicating the onset of a voltage-independent rate-limiting process associated with electron-hole-pair creation and/or annihilation. At high photo-excitation rates, voltammograms are superlinear in shape, indicating, for the voltage ranges studied here, a voltage-dependent rate-limiting process associated with surface electrochemical oxidation. As PEC etching proceeds, the thin film becomes rough at the nanoscale, and ultimately the self-limiting etch kinetics lead to an ensemble of nanoparticles. This change in InGaN film volume and morphology leads to a characteristic dependence of PEC etch rate on time: an incubation time, followed by a rise, then a peak, then a slow decay.
Quantum-size-controlled photoelectrochemical fabrication of epitaxial InGaN quantum dots
Nano Letters
We demonstrate a new route to the precision fabrication of epitaxial semiconductor nanostructures in the sub-10 nm size regime: quantum-size-controlled photoelectrochemical (QSC-PEC) etching. We show that quantum dots (QDs) can be QSC-PEC-etched from epitaxial InGaN thin films using narrowband laser photoexcitation, and that the QD sizes (and hence bandgaps and photoluminescence wavelengths) are determined by the photoexcitation wavelength. Low-temperature photoluminescence from ensembles of such QDs have peak wavelengths that can be tunably blue shifted by 35 nm (from 440 to 405 nm) and have line widths that narrow by 3 times (from 19 to 6 nm).
Nanophotonic Architectures for Nanoscale Light Control (invited)
Abstract not provided.
Precision Laser Assisted Photoelectrochemical Fabrication of III-V Semiconductor Quantum Structures
Abstract not provided.
InGaN Quantum Dots for Room Temperature Single Photon Sources
Abstract not provided.
InGaN Quantum Dots for High Efficiency Blue and Green Light Emitters
Abstract not provided.
Laser assisted photoelectrochemical etching of InGaN quantum structures
Abstract not provided.
19 Results