In the first part of this talk a brief review on the non linear laser imaging techniques will be displayed. In particular, two photon fluorescence microscopy, lifetime imaging, multispectral imaging, second harmonic generation microscopy principles will be described.

In the second part of the talk there will be an overview on the applications of these techniques in the field of biomedical imaging.  In particular, tumor detection in tissue imaging applications will be shown in different fields, from urology to gastrointestinal surgery, dermatology and brain surgery.

Morpho-functional characterization of tissue pathologies will be displayed as an interesting tool for tumor early diagnosis.  Other type of non tumor disease applications will be also shown together with the demonstration on using laser imaging for follow up of laser therapies.

In the last part of the talk, a fiber based endoscope based on multidimensional spectral detection (one photon fluorescence, lifetime and Raman detection) will be described with particular applications of tumor detection.

The densest way to pack objects in space, also known as the packing problem, has intrigued scientists and philosophers for millenia. Today, packing comes up in various systems over many length scales from batteries and catalysts to the self-assembly of nanoparticles, colloids and biomolecules. Despite the fact that so many systems' properties depend on the packing of differently-shaped components, we still have no general understanding of how packing varies as a function of particle shape. Here, we carry out an exhaustive study of how packing depends on shape by investigating the packings of over 55,000 polyhedra. By combining simulations and analytic calculations, we study families of polyhedra interpolating between Platonic and Archimedean solids such as the tetrahedron, the cube, and the octahedron. Our resulting density surface plots can be used to guide experiments that utilize shape and packing in the same way that phase diagrams are essential to do chemistry. The properties of particle shape indeed are revealing why we can assemble certain crystals, transition between different ones, or get stuck in kinetic traps. 

References

1)      Chen, E. R; Klotsa, D; Engel, M.; Damasceno, P.F, Glotzer, S. C. Compexity in Surfaces of Densest Packing for Families of Polydedra. Physical Review X 2014, 4, 011024

2)      Klotsa, D; Chen, E. R; Engel, M.; Glotzer, S. C. Intermediate Crystalline Structures of Colloidal In Shape Space. Soft Matter 2018, 14, 8692

See also (Popular Science):  

- New scientist (http://www.newscientist.com/article/dn25163-angry-alien-in-packing-puzzle-shocks-mathematicians.html#.VQBaxGTkdNt)

- Physicsworld (http://physicsworld.com/cws/article/news/2014/mar/03/finding-better-ways-to-pack-polyhedral)

- APS Synopsis (http://physics.aps.org/synopsis-for/10.1103/PhysRevX.4.011024)

Public lecture video: https://www.youtube.com/watch?time_continue=3&v=6xy-5K8UV94

Living matter, such as biological tissue, can be seen as a nonequilibrium hierarchical assembly of assemblies of smaller and smaller active components, where energy is consumed at many scales. The remarkable properties (e.g. functionality and versatility) of such living or “active-matter” systems make them promising candidates to study and synthetically design. While many active-matter systems reside in fluids (solution, blood, ocean, air), so far, studies that include hydrodynamic interactions have focused on microscopic scales in Stokes flows, where the active particles are small <100μm and the Reynolds number, Re <<1. At those microscopic scales viscosity dominates and inertia can be neglected. What happens as swimmers slightly increase in size (say ~0.1mm-100cm) or as they form larger aggregates and swarms? The system then enters the intermediate Reynolds regime where both inertia and viscosity play a role, and where nonlinearities are introduced in the fluid. In this talk, I will present a simple model swimmer used to understand the transition from Stokes to intermediate Reynolds numbers, first for a single swimmer, then for pairwise interactions and finally for collective behavior. We show that, even for a simple model, inertia can induce hydrodynamic interactions that generate novel phase behavior, steady states and transitions.

References

1)       Klotsa, D; Baldwin, K. A; Hill, R. J. A; Bowley, R. M.; Swift, M. R. Propulsion of a Two-Sphere Swimmer. Physical Review Letters  2015, 115, 248102

2)      Dombrowski, T; Jones, S. K.; Katsikis, G.; Bhalla, A. P. S.; Griffith, B. E.; Klotsa, D. Transition in Swimming Direction in a Model Self-Propelled Inertial Swimmer. Physical Review Fluids 2019, 4, 021101

See also (Popular Science):  

- Physics Today (https://physicstoday.scitation.org/do/10.1063/PT.5.7225/full/)

- Video Sixty symbols (https://www.youtube.com/watch?v=aJ6KRrEda-Y)

Atomistic calculations based on density functional theory and many-body perturbation theory provide predictive understanding of materials at the electronic level that complement experimental synthesis and characterization studies. Recent advances in modern software development and high-performance computing have enabled the high-throughput calculation of materials properties that can guide the discovery of new materials with targeted functionalities. Semiconductors in particular are a versatile class of functional materials with numerous commercial applications in electronic and optoelectronic devices. Recent interest has focused on ultrawide-band-gap semiconductors (i.e., semiconductors with gaps wider than the 3.5 eV gap of GaN) for applications in energy-efficient power electronics and deep-ultraviolet light emission for sterilization and water purification. However, existing ultrawide-band-gap semiconductors such as AlGaN alloys, Boron Nitride (BN), diamond, and Gallium Oxide (Ga2O3) face several challenges with regards to their doping, thermal conductivity, and efficiency of light generation.

In this talk I will present our recent results on the computational discovery of new ultrawide-gap semiconductors with superior properties compared to the state of the art. I will present rutile GeO2 as a promising alternative to nitrides and Ga2O3 for high-power electronic applications. I will discuss its superior electrical and thermal conductivity to Ga2O3 and the possibility of ambipolar doping. I will also discuss Boron-containing BAlGaN alloys as alternative materials to AlGaN for efficient deep-ultraviolet light emission thanks to their lattice matching to AlN (and hence their lower threading dislocation density) and the emission of transverse-electric polarized light, which facilitates light extraction from polar devices. Our computational results can guide experimental efforts in the synthesis and characterization of these promising new semiconductors.

This work was performed in collaboration with Kelsey Mengle, Sieun Chae, John Heron, Logan Williams, and Kevin Greenman. It was supported by the Designing Materials to Revolutionize and Engineer our Future (DMREF) Program under Award No. 1534221, funded by the U.S. National Science Foundation. It also used resources of the National Energy Research Scientific Computing Center, a DOE office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.