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Recent experimental work has demonstrated production of quasi free-standing graphene by gold intercalation. The intercalation weakens the coupling of adjacent graphene layers and yields Dirac fermion behavior of monolayer graphene.

Researchers at Clark Atlanta University and Morehouse College have investigated the electronic characteristics of gold intercepted graphene bilayer under a perpendicularly applied electric field. Evolution of the band structure of intercalated graphene as a function of the bias is studied by means of density-functional theory including interlayer van der Waals interactions. The findings suggest a controllable band gap opening in gold intercalated graphene for future device applications. The work was published in Phys. Chem. Chem. Phys.

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Recent experimental work has demonstrated production of quasi free-standing graphene by methane intercalation. The intercalation weakens the coupling of adjacent graphene layers and yields Dirac fermion behaviour of monolayer graphene.

Researchers at Clark Atlanta University and Spelman College have investigated the electronic characteristics of methane intercepted graphene bilayer under a perpendicularly applied electric field. Evolution of the band structure of intercalated graphene as a function of the bias is studied by means of density-functional theory including interlayer van der Waals interactions. The findings suggest a controllable band gap opening in methane-intercalated graphene for future device applications.

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Banner promoting nano exhibición in downtown Humacao.

The PREM Nano Exhibición is presented in collaboration with Humacao’s Casa Roig Museum from March to December 2013. The basic exhibit was awarded to PREM by NISENet. Additional modules on “Nano, Stained Glasses and Materials in Historical Casa Roig” are being developed with the participation of students from local schools.

In 2014 the exhibit will be presented at the Arecibo Astronomical Observatory. A new module “From Nano to the Cosmos” will be developed in this new alliance between the Observatory and the Humacao PREM.

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• CVD Graphene was synthesized at PENN.
• A Field Effect Transistor was fabricated at UPRH .
• No lithography was used (i.e. no harsh chemicals used) to define the source and drain electrodes, instead a TEM grid was used as a shadow mask. This is new to graphene based device fabrication.
• The device was tested in vacuum under UV irradiation
• We found that it was possible to dope graphene with no change in the charge mobility (see top figure).
• The process was reversible.

 
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NSF-JSU-UCSB PREM members arranged  summer program for K12 minority participants, to help local science students in their mission of enhancing scientific literacy to wider audiences.

This program is very popular in Jackson, MS and it helps to raise the number of STEM minority students every year

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JSU & UT San Antonio team members have reported the development of multifunctional popcorn shape iron magnetic core- gold plasmonic shell nanotechnology-driven approach for targeted magnetic separation & enrichment, label-free surface enhanced Raman spectroscopy detection, and selective photothermal destruction of MDR Salmonella DT104. Our result shows that magnetic core–plasmonic shell popcorn shape nanoparticle based assay is rapid, takes about 30 minutes from bacterium binding to separation, enrichment, selective detection and photothermal killing.

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Functionalization of Au and Ag nanoparticles with thiol molecules has been a topic of high interest, due to their peculiar and unique properties of their organic-metal interfaces. Thiols are well-known ligand molecules because they are able to form a self-assembled monolayer on the metal nanoparticle surface through a strong metal-sulfur covalent bond. Therefore the control of the adsorption and the appearance of structural changes on ligand passivated gold or silver nanoparticles are of primary importance.

Initial Goal: To perform ab initio density functional theory with the SIESTA code to determine the most stable adsorption sites, and specify the most favorable adsorption modes for the methyl-thiol molecule on an icosahedral Au55 and Ag55 clusters.

In collaboration with our colleagues from Northwestern, we recently found that the favorable absorbed sites for the thiol molecule were on Bridge sites for both Au55 and Ag55 clusters. We found a slightly variation on the atomic Au55 arrangement that could affect the electronic and magnetic properties. We are extending this approach to the case in which the cluster is capped with two and more molecules.

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Cross-sectional slice of NaGdF4: Yb/Er NPs in fibroblast cells.

Rare-earth doped nanoparticles (NPs) are known to have exceptional optical properties such as strong absorption and sharp emission lines. Since the optical properties are due to the f-f electron transitions, these nanoparticles do not photobleach like organic dyes or blink like quantum dots. Through the process known as upconversion, rare-earth ions can convert multiple lower energy photons into higher energy ones. We utilize this to engineer our NPs to absorb near-infrared light (980 nm) and emit in the visible (550 nm, 660 nm) and NIR (800 nm). Also, these NPs do not require high energy densities such as conventional two-photon processes and can be excited with pulsed and continuous sources, making them ideal for biomedical purposes. The 980 nm excitation for ytterbium and erbium co-doped systems, such as the KMgF3: Yb/Er and NaGdF4: Yb/Er NPs used herein, is advantageous due to the low scattering and absorption of tissue in this region.

Fibroblast cells were grown in multiwell plates and incubated with 100μg/mL doses of NPs. In order to image the cells with PEGylated nanoparticles, DAPI was used to stain the nucleus (blue), and a phalloidin stain for the cytoplasm  (red). The cells were then  treated with upconverting nanoparticles, and 3D images were obtained with a multiphoton microscope. It was seen that the PEGylated NPs are easily taken up by the cells and migrate into the nucleus. The light blue and green are correlated to upconversion emission which came from inside the nucleus and cytoplasm, respectively, showing that at the time of fixing, some NPs were in the process of migrating into the nucleus. These NPs will be very useful for cancer labeling , theranostics, and selective killing of cells through infrared photodynamic therapy.

Optical absorption of functionalized gold NP at 520 nm (disaggregated) and 620 nm (aggregated), as measured by photoacoustic spectroscopy. Introduction of FeCl3 (an oxidizer) causes the NP to aggregate, increasing the signal at 620 nm.

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