98 research outputs found
Approach to Data Science with Multiscale Information Theory
Data Science is a multidisciplinary field that plays a crucial role in
extracting valuable insights and knowledge from large and intricate datasets.
Within the realm of Data Science, two fundamental components are Information
Theory (IT) and Statistical Mechanics (SM), which provide a theoretical
framework for understanding dataset properties. IT enables efficient storage
and transmission of information, while SM focuses on the behavior of systems
comprising numerous interacting components. In the context of data science, SM
allows us to model complex interactions among variables within a dataset. By
leveraging these tools, data scientists can gain a profound understanding of
data properties, leading to the development of advanced models and algorithms
for analysis and interpretation. Consequently, data science has the potential
to drive accurate predictions and enhance decision-making across various
domains, including finance, marketing, healthcare, and scientific research.
In this paper, we apply this data science framework to a large and intricate
quantum mechanical system composed of particles. Our research demonstrates that
the dynamic and probabilistic nature of such systems can be effectively
addressed using a Multiscale Entropic Dynamics (MED) approach, derived from the
Boltzmann methods of SM. Through the MED approach, we can describe the system's
dynamics by formulating a general form of the Nonlinear Schr\"odinger equation
and how it can be applied to various systems with particles and
quasi-particles, such as electrons, plasmons, polarons, and solitons. By
employing this innovative approach, we pave the way for a deeper understanding
of quantum mechanical systems and their behaviors within complex materials.Comment: 12 page
Electron irradiation induced reduction of the permittivity in chalcogenide glass (As2S3) thin film
We investigate the effect of electron beam irradiation on the dielectric
properties of As2S3 Chalcogenide glass. By means of low-loss Electron Energy
Loss Spectroscopy, we derive the permittivity function, its dispersive
relation, and calculate the refractive index and absorption coefficients under
the constant permeability approximation. The measured and calculated results
show, to the best of our knowledge, a heretofore unseen phenomenon: the
reduction in the permittivity of <40%, and consequently a modification of the
refractive index follows, reducing it by 20%, hence suggesting a significant
change on the optical properties of the material. The plausible physical
phenomena leading to these observations are discussed in terms of the homopolar
and heteropolar bond dynamics under high energy absorption.Comment: 22 pages, 7 figures, manuscript in preparation to send to Physical
Review
Polyglutamine Disruption of the Huntingtin Exon 1 N Terminus Triggers a Complex Aggregation Mechanism
Simple polyglutamine (polyQ) peptides aggregate in vitro via a nucleated growth pathway directly yielding amyloid-like aggregates. We show here that the 17-amino-acid flanking sequence (HTTNT) N-terminal to the polyQ in the toxic huntingtin exon 1 fragment imparts onto this peptide a complex alternative aggregation mechanism. In isolation, the HTTNT peptide is a compact coil that resists aggregation. When polyQ is fused to this sequence, it induces in HTTNT, in a repeat-length dependent fashion, a more extended conformation that greatly enhances its aggregation into globular oligomers with HTTNT cores and exposed polyQ. In a second step, a new, amyloid-like aggregate is formed with a core composed of both HTTNT and polyQ. The results indicate unprecedented complexity in how primary sequence controls aggregation within a substantially disordered peptide and have implications for the molecular mechanism of Huntington\u27s disease
Revealing microstructure and dislocation behavior in BAlN/AlGaN heterostructures
We reveal the microstructure and dislocation behavior in 20-pair B0.14Al0.86N/Al0.70Ga0.30N multiple-stack heterostructures (MSHs) exhibiting an increasing dislocation density along the c-axis, which is attributed to the continuous generation of dislocations (edge and mixed-type) within the individual B0.14Al0.86N layers. At the MSH interfaces, the threading dislocations were accompanied by a string of V-shape pits extending to the surface, leading to interface roughening and the formation of surface columnar features. Strain maps indicated an approximately 1.5% tensile strain and 1% compressive strain in the B0.14Al0.86N and Al0.70Ga0.30N layers, respectively. Twin structures were observed, and the MSH eventually changed from monocrystalline to polycrystalline.Acknowledgments The KAUST authors acknowledge the support of the GCC Research Program REP=1=3189-01-01, Baseline BAS=1=1664-01-01, and Equipment BAS=1=1664-01-07. The work at QU was supported by the GCC Research Program GCC-2017-007. The work at the Georgia Institute of Technology was supported in part by DARPA under Grant No. W911NF-15-1-0026 and NSF under Grant No. DMR-1410874. R.D.D. acknowledges the additional support of the Steve W. Chaddick Endowed Chair in Electro-Optics and Georgia Research Alliance
Intrinsic efficiency limits in low-bandgap non-fullerene acceptor organic solar cells
In bulk heterojunction (BHJ) organic solar cells (OSCs) both the electron affinity (EA) and ionization energy (IE) offsets at the donor–acceptor interface should equally control exciton dissociation. Here, we demonstrate that in low-bandgap non-fullerene acceptor (NFA) BHJs ultrafast donor-to-acceptor energy transfer precedes hole transfer from the acceptor to the donor and thus renders the EA offset virtually unimportant. Moreover, sizeable bulk IE offsets of about 0.5 eV are needed for efficient charge transfer and high internal quantum efficiencies, since energy level bending at the donor–NFA interface caused by the acceptors’ quadrupole moments prevents efficient exciton-to-charge-transfer state conversion at low IE offsets. The same bending, however, is the origin of the barrier-less charge transfer state to free charge conversion. Our results provide a comprehensive picture of the photophysics of NFA-based blends, and show that sizeable bulk IE offsets are essential to design efficient BHJ OSCs based on low-bandgap NFAs
Coexistence of plasmonic and magnetic properties in Au89Fe11 nanoalloys
We describe an environmentally friendly, top-down approach to the synthesis of Au89Fe11 nanoparticles (NPs). The plasmonic response of the gold moiety and the magnetism of the iron moiety coexist in the Au89Fe11 nanoalloy with strong modification compared to single element NPs, revealing a non-linear surface plasmon resonance dependence on the iron fraction and a transition from paramagnetic to a spin-glass state at low temperature. These nanoalloys are accessible to conjugation with thiolated molecules and they are promising contrast agents for magnetic resonance imaging
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