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.

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.

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.

 

Segregation-induced ordered superstructures

  • By Burcu Ozden
  • 21 March 2018

Michael Widom and his colleagues showed what happens at the grain boundaries of one particular alloy of the metals nickel and bismuth that makes it brittle in their paper published in Science. Using advanced electron microscopes, Widom’s collaborators at Lehigh University scrutinized these microscopic grain boundaries at an atomic level. In a "very heroic experimental program" they discovered that when grains met, the bismuth and nickel atoms realigned into lattices to form layered superstructures at the grain boundaries. These superstructures had previously been thought to exist only rarely in some alloys. Finding it at many different boundaries led the team to conclude that these superstructures are probably much more common than many people had thought. 

Chiral nanocluster with open shell electronic structure and helical face-centered cubic framework

  • By Leena Aggarwal
  • 2 March 2018

Owing to high surface to volume ratios and chemical potential, nanoparticles possess unique optical, electrical, and thermal properties, which constitute the basis of novel applications in sensing, catalysis, nanoelectronics, bio-tagging etc. Despite the great advances in the synthesis, the total structure determination of nanoclusters still remains to be a major challenge. Recently Hyung J. Kim and their colleagues have reported the synthesis and crystal structure of a nanocluster composed of 23 silver atoms capped by 8 phosphine and 18 phenylethanethiolate ligands in the journal of Nature Communications.

Engineering of spin canting across core/shell Fe3O4/MnxFe3−xO4 nanoparticle

  • By Leena Aggarwal
  • 27 February 2018

In the recently published paper in Scientific Reports, Sara A. Majetich and their colleagues have demonstrated the engineering of spin canting across a Magnetic nanoparticles (MNP) via the Dzyaloshinskii-Moriya interaction (DMI). In this paper, they have shown that strong DMI can lead to magnetic frustration within the shell and cause canting of the net particle moment. These results have illuminated how core/shell nanoparticle systems can be engineered for spin canting across the whole of the particle, rather than solely at the surface.

 

Building Smarter Windows

  • By Burcu Ozden
  • 21 February 2018

Paul Leu and his student Sajad Haghanifar, a PhD candidate, developed a new type of glass 1,000 times thinner than a human hair which could potentially used as solar panels for smart windows.

While the solar energy industry is expanding — at an average annual rate of 68 percent from 2006 to 2016, according to the Solar Energy Industries Association — solar panels and solar cells still have an efficiency issue.

Paul Leu said, " Any light that is not being absorbed by your solar cell is decreasing the efficiency of your solar panel," and added “Anything you can do to increase your efficiency is good.”

Leu said that the new glass they developed has advantagous of scattering light energy at different angles, giving the light that does bounce off a better chance to be trapped and converted into useable energy

He added, “With these nanostructures, you can get the reflection rate close to zero.” 

Electron Transfer without Overcoming a Barrier

  • By Burcu Ozden
  • 14 February 2018

In the recently accepted paper in Physical Review Letter, Hrvoje Petek and his colleagues investigate the coherent electron transfer from an interface state that forms upon chemisorption of Ag nanoclusters onto graphite to a σ symmetry interlayer band of graphite. Interfacial charge transfer is a fundamental process in heterogeneous and plasmonically enhanced catalysis.

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