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Program Highlights

Band Gap Opening in Methane Intercalated Graphene

May 19, 2013

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.

PREM’s Nano Exhibición

May 19, 2013

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.

Doping graphene with UV light

May 19, 2013

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.

JSU-UCSB PREM’s Summer Program for K12 Participants: Impact on the Community

May 7, 2013

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

Multifunctional Nanoparticles Can Target, Separate and Destroy Bacteria

May 7, 2013

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.

Biomedical Imaging with NIR Upconverting Nanoparticles

May 7, 2013

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.

A Nanoparticle-Based Sensor of Oxidative Stress

May 7, 2013

Oxidative stress is a critical process in biological systems, involved in both normal and pathological functions; thus it is a commonly measured endpoint. Current methods for measuring oxidative stress are affected by artifacts, such as auto-oxidation. We are developing a new measurement approach based on the aggregation of functionalized gold NP in the presence of reactive oxygen species.

Measuring the strength of individual metal nanoparticles

May 7, 2013

It is well established that matter behaves in a different manner at the nanoscale compared with their bulk counterparts. Mostly, this is due to confinement of electron, increased surface to volume ratio, composition, etc.; therefore, the study of matter at the nanoscale is of crucial relevance to continue the development of nano-devices that surrounds our everyday life.

Boundary Study of the Flow of the Concentrated Suspensions 

October 3, 2012

Abrasive wear induced by the slow flow of concentrated slurry is encountered in many industrial problems. In this work, using a combination of experiment and theory, the coupled issues of the rheology of a concentrated solids-laden liquid and the boundary wear generated as it flows in confined domain in the geometry of simple shear are demonstrated. An experiment is performed with different abrasive particles, specimen materials and under different test conditions such as abrasive concentration and angular velocity. Using the von Mises yield criterion the load at which the plastic yield begins and boundary wear becomes observable is determined. In order to reveal the morphology of the surface, scanning electron microscopy (SEM) were used.

Reversible Behavior in 17nm Fe3O4 Capped Janus Particles

October 3, 2012

The structure transitions from staggered to loose double chain configuration as the voltage is ramped down at constant magnetic field. As the voltage is ramped back up the structure reforms and the staggered character begins to re-emerge.

Molecular Dynamics Simulations of Drops Falling on a Surface

October 3, 2012

Molecular dynamics simulations are used to study the dynamics of drop splashing on a solid surface. In agreement with experiment, we observe that splashes occur only in the presence of vapor. We are investigating how the flow in the vapor produces the stress which tears the drop into fragments, and the effects of surface wettability patterns on the final state.

Numerical Simulations of Droplet Deformation Under Shear Flow

October 3, 2012

Numerical simulations of the deformation of a droplet in viscous fluid under shear flow are performed with the Lattice Boltzmann method (LBM) based on the Cahn-Hilliard diffuse interface approach. The Degree of confinement between two parallel walls, which is defined as the ration between drop diameter 2R and the wall separation H and can play an important role and affect the dynamics of droplet deformation, is studied by decreasing the distance between the walls.

Self-Assembly as a Method to Device Construction

October 3, 2012

Surfactant molecules of Tau-3PDP and Phs-3PDP self-assemble into fractal patterns when placed on an air-water interface. These fractal crystals can subsequently be coated with various metallic films and used in electronic devices. Several labs are currently trying to unlock the potential of self-assembled organic molecules to define complex templates for the rapid processing of nanoscale electronic devices, where exceptionally high surface areas can be accessed in a bottom-up fashion. Before putting the structures to use, an understanding of how to control the growth of the crystals is required. Using Brewster Angle Microscopy coupled to a Langmuir trough we have been able to control the complexity (or fractal dimension) of self-assembled crystals through changes in temperature. The image analysis shows higher fractal dimensions at lower temperatures. We are currently trying to use the fractals as a template by reducing gold on the interface.

Organic phase behavior connects to an array of inorganic structure

October 3, 2012

The self-assembly dynamics of our two-dimensionally confined organic films defines the composite nanostructure. Mimicking biology, highly organized templates lead to polycrystallinity, and sparse films lead to large single crystals, but films on the phase envelope lead to complex composites.

PREM Multidisciplinary Research and Education in Computational Materials Charge and Spin Transport and quantum Hall effect in 2D Systems

July 2, 2012
We have developed new state of the art density matrix renormalization group (DMRG) and transport codes, which can deal with large electron systems with interaction. Right two figures represent some results we obtained with our collaborators. On the right side, top panel shows our quantum phase diagram for Haldane honeycomb model with spin orbit interaction. It shows that using gate voltage V one can tune into quantum Hall effect (QAHE) by splitting quantum spin Hall effect (QSHE) for system without time reversal symmetry. Bottom panel shows the entanglement gap extrapolates to finite value at thermodynamic limit demonstrating topological order of the 5/2 system.

Approaching the intrinsic band gap in suspended high-mobility graphene nanoribbons

July 2, 2012

Electrical transport measurements on a suspended ultra-low-disorder graphene nanoribbon (GNR) with nearly atomically smooth edges have been carried out by Zhixian Zhou and co-workers at Wayne State University that reveal a high mobility exceeding 3000 cm2 V−1 s−1 and an intrinsic band gap.

Periodic unit cell used in the calculation is shown shaded in green. The zoom-in regions show the spatial distribution of spin-up (cyan) and spin-down (red) magnetization.

Periodic unit cell used in the calculation is shown shaded in green. The zoom-in regions show the spatial distribution of spin-up (cyan) and spin-down (red) magnetization.

Gallaudet, the National University for the Deaf, joins the PREM Program

June 26, 2012

In 2011, Gallaudet University joined the Howard, Hopkins Prince Georges Community College PREM.
Three Gallaudet students were mentored by Prof. Paul Sabila in summer research at Howard in Jason Matthews’ research group.
In addition to research, the students took part in nanotechnology training together with hearing students.
They were trained to use advanced instrumentation including electron and atomic force microscopes and lithographic equipment in the Howard Nanofabrication Facility together with their fellow hearing students.

Self-Assembly of Biofunctional Polymer on Graphene Nanoribbons

May 14, 2012
Clark Atlanta University researchers supported by the NSF PREM project worked on supramolecular self-assembly of biofunctional-modified poly(2 methoxystyrene) on graphene nanoribbons. The bioactive polymer has attracted a considerable interest owing to its versatile properties as a bisosensor. However, the formation of regular patterned structures for the polymer is difficult, which greatly hampers its applications. The combined experimental and theoretical work demonstrates that the glycol modified polymer can self-assemble into structured nanopatterns on graphene nanoribbons with preserved bioactivity. The findings demonstrate that the assembly yields a prospective route to novel nanomaterial systems.

Tunable bands in biased multilayer epitaxial graphene

May 14, 2012

Clark Atlanta University and Georgia Tech. researchers supported by the NSF PREM project studied the electronic characteristics of multilayer epitaxial graphene under a perpendicularly applied electric bias.