Research

Four-dimensional physics in two dimensions

  • By Leena Aggarwal
  • 5 January 2018

Kevin Chen and team have demonstrated that the behavior of particles of light can be made to match predictions about the four-dimensional version of the "quantum Hall effect"—a phenomenon that has been at the root of three Nobel Prizes in physics—in a two-dimensional array of "waveguides."

“For the first time, physicists have built a two-dimensional experimental system that allows them to study the physical properties of materials that were theorized to exist only in four-dimensional space"

Understanding of the superior stability of Silicon- and oxygen-containing hydrogenated amorphous carbon in harsh environments

  • By Leena Aggarwal
  • 3 January 2018

Recently, Tevis D. B. Jacobs and colleagues have shown how silicon- and oxygen-containing hydrogenated amorphous carbon (a-C:H:Si:O) coating enhance the thermal stability in vacuum, but tremendously increases the thermo-oxidative stability and the resistance to degradation upon exposure to the harsh conditions of low Earth orbit (LEO). These findings provide a novel physically-based understanding of the superior stability of a-C:H:Si:O in harsh environments compared to a-C:H.

Single-shot condensation of exciton polaritons and the hole burning effect

  • By Leena Aggarwal
  • 10 September 2018

The single-shot measurements offer a unique opportunity to study fundamental properties of non-equilibrium condensation in the presence of a reservoir. David Snoke and his colleagues have recently reported an insight into spontaneous condensation by imaging long-lifetime exciton polaritons in a high-quality inorganic microcavity in a single-shot optical excitation regime, without averaging over multiple condensate realisations. The results are published in the Journal of Nature Communications. They have demonstrated that how condensation is strongly influenced by an incoherent reservoir and that the reservoir depletion, the so-called spatial hole burning, is critical for the transition to the ground state.

Low‐power electrochemically tunable graphene synapses for neuromorphic computing

  • By Ke Xu
  • 24 July 2018

Feng Xiong and his group developed an “artificial synapse” that does not process information like a digital computer but rather mimics the analog way the human brain completes tasks. 

For applications in neuromorphic computing, Xiong and his team focuses on the design of computational hardware inspired by the human brain and built graphene-based artificial synapses in a two-dimensional honeycomb configuration of carbon atoms. Graphene’s conductive properties allowed the researchers to finely tune its electrical conductance, which is the strength of the synaptic connection or the synaptic weight.

Their work was published in the recent issue of the journal Advanced Materials. Other co-authors include Mohammad Sharbati (first author), Yanhao Du, Jorge Torres, Nolan Ardolino, and Minhee Yun.

Ultrafast Microscopy of Spin-Momentum Locked Surface Plasmon Polaritons

  • By Leena Aggarwal
  • 27 June 2018

The recently published paper in journal of ACS NANO on Ultrafast Microscopy of Spin-Momentum Locked Surface Plasmon Polaritons is an essential research for designing optical elements to control spin-polarized SPP (surface plasmon polaritons) fields on the nano femto scale. Hrvoje Petek and his colleagues have shown two-photon photoemission electron microscopy images formed by coupling and propagation of longitudinal and transverse components of SPP fields of light. Further, they have also shown the spin-momentum locked SPP wave packets launched with circularly polarized excitation propagate at the same phase and group velocities as for the linearly polarized excitation using time-resolved experiments.

 

 

Topological Protection of Photonic Mid-Gap Defect Modes

  • By Burcu Ozden
  • 12 June 2018

Kevin Chen and his colleagues have demonstrated in a proof-of-concept experiment that they can contain light in such a way that makes it highly insensitive to defects that might be present in a material.

"From the perspective of photonic engineers, this is a wonderful learning opportunity to see the connections between lightwave engineering at length scale of micrometers, and quantum mechanics that typically deals with electron waves at length scale 10,000 times smaller," noted Kevin P. Chen.

Large enhancement of response times of a protein conformational switch by computational design

  • By Leena Aggarwal
  • 16 April 2018

Lillian Chong and her colleagues have recently reported, in the Journal of Nature Communications, a computational design strategy in synergistic combination with biophysical experiments to rationally improve the response time of an engineered protein-based Ca2+-sensor in which the switching process occurs via mutually exclusive folding of two alternate frames. This strategy identifies mutations that increase switching rates by as much as 32-fold, achieving response times on the order of fast physiological Ca2+ fluctuations. This computational design strategy is general and may aid in optimizing the kinetics of other protein conformational switches.

Critical heat flux enhancement in pool boiling through increased rewetting on nanopillar array surfaces

  • By Leena Aggarwal
  • 12 April 2018

Boiling is a key heat transfer process for a variety of power generation and thermal management technologies. The enhancement in both the critical heat flux (CHF) and the critical temperature at CHF of the substrate and effectively increase the limit of boiling before the boiling crisis is triggered. By using only nanopillars with a systematic variation in height and well-defined geometrical dimensions, Paul W. Leu and colleagues have established a direct link between the enhancement in capillary force and the boiling performance of a substrate. This provides new insights about design of surface textures not only to amplify the heat flux, but also to achieve an enhancement in the temperature at critical heat flux. These results are published in Scientific Reports.

Highly Efficient Strategy for Constructing New Types of Peptide Macrocycles

  • By Burcu Ozden
  • 10 April 2018

Peng Liu and his colleagues report a highly efficient and generally applicable strategy for constructing new types of peptide macrocycles using palladium-catalyzed intramolecular C(sp3)–H arylation reactions on their newly published paper in Nature Chemistry. 

This strategy provides a powerful tool to address the long-standing challenge of size- and composition-dependence in peptide macrocyclization, and generates novel peptide macrocycles with uniquely buttressed backbones and distinct loop-type three-dimensional structures.

Size, Shape, and Composition-Dependent Model for Metal Nanoparticle Stability Prediction

  • By Leena Aggarwal
  • 4 April 2018

Giannis Mpourmpakis and his students have proposed a bond-centric (BC) model able to capture cohesive energy trends over a range of monometallic and bimetallic nanoparticles and mixing behavior (excess energy) of nanoalloys, in great agreement with DFT calculations. This model utilizes to calculate the energetics of any nanoparticle morphology and chemical composition, thus significantly accelerating nanoalloys design. This work introduces a simple yet very powerful tool for nanoalloy design that can potentially help elucidate the energetics of alloy MNP genomes.

 

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