Article
Chemistry, Multidisciplinary
Raphael Sarfati, Christopher P. Calderon, Daniel K. Schwartz
Summary: Although there is no comprehensive theory to describe transport behavior within porous environments, experimental results show that the diffusion of nanoparticles is more effective in fluctuating porous matrices compared to static ones, due to the enhancing effects of matrix fluctuations on the diffusion coefficient and cooperative gate-opening motions between matrix particles and nanoparticle probes.
Article
Mechanics
Gaia Pozzoli, Benjamin De Bruyne
Summary: We studied the transport properties of a one-dimensional Brownian motion with partially absorbing traps. We found that the environment enhances diffusion when the number of traps is finite, while it inhibits diffusion when there are an infinite number of traps.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2022)
Article
Chemistry, Multidisciplinary
Michael Wais, Filchito Renee G. Bagsican, Natsumi Komatsu, Weilu Gao, Kazunori Serita, Hironaru Murakami, Karsten Held, Iwao Kawayama, Junichiro Kono, Marco Battiato, Masayoshi Tonouchi
Summary: The confinement of quasiparticles in carbon nanotubes leads to anisotropic electronic and optical properties. In random ensembles of nanotubes, this anisotropy disappears. We compare the dynamics of quasiparticles in aligned and random carbon nanotube networks and find that alignment strongly influences their behavior.
Article
Thermodynamics
Ila Thakur, Atul Srivastava, Shyamprasad Karagadde
Summary: A recent observation found that when espresso is poured into steamed milk, alternating layers of milk and coffee-enriched regions are formed, known as double-diffusive convection (DDC). Inspired by this, an extensive numerical investigation of DDC was conducted. The transitions between four different flow regimes were revealed, and the survival time of double-diffusive layers (DDLs) was found to follow the same proportionality as the onset of the layered regime. The heat transfer coefficients at the sidewalls were obtained, and it was found that the overall heat transfer was lower in the presence of DDC.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2023)
Article
Physics, Applied
Yuhui Zhang, Michael S. Shur
Summary: The study investigated the terahertz detection performance and operating regimes of graphene plasmonic FETs using a hydrodynamic model. Continuous wave detection simulations showed similar response sensitivity to other materials, while pulse detection results indicated a very short response time favored rapid/high-sensitively detection. Analysis on the mobility dependence of response time revealed similar detection regimes to traditional semiconductor materials.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Engineering, Electrical & Electronic
Yang Shen, Yu-Chao Hua, Han-Ling Li, S. L. Sobolev, Bing-Yang Cao
Summary: In this article, the phonon Monte Carlo method is used to investigate the thermal transport process in wide-bandgap semiconductor devices. The results provide a thermal resistance model that can address the issues of thermal spreading, ballistic effects, and the influence of phonon dispersion. This research is important for predicting junction temperatures and developing thermal management strategies.
IEEE TRANSACTIONS ON ELECTRON DEVICES
(2022)
Article
Instruments & Instrumentation
Jianli Wang, Lu Chen, Cong Wang, Chengkun Mao, Hongmei Yu, Zhenyu Cui
Summary: A homemade inelastic tunneling spectroscope was used to investigate the electrical and thermal resistances of nanosized metallic contacts established by Lorentz force pressing two wires crosswise in a magnetic field. The study found that the thermal contact resistance increases linearly with the electrical counterpart, indicating the validity of the Wiedemann-Franz law at clean metallic contacts.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2021)
Article
Physics, Applied
Ji Ung Lee
Summary: The study presents a quasi-ballistic transport model for highly scaled transistors, with a small number of fitting parameters derived from the underlying physics of transport in ballistic conductors. The model is shown to perform well against a wide range of nanoscale transistors, demonstrating its effectiveness in describing transport in modern transistors with channel lengths approaching the mean scattering length of carriers.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Fluids & Plasmas
Tirthankar Banerjee, Robert L. Jack, Michael E. Cates
Summary: The long-lasting effects of initial conditions on dynamical fluctuations in one-dimensional diffusive systems are analyzed. The study shows analytically that the memory of initial conditions is mediated by a single static quantity, a generalized compressibility. Through extensive Monte Carlo simulations, the predictions are verified.
Article
Chemistry, Physical
Ata-ur-Rehman, Ghulam Ali, Muhammad Bilal, Muhammad Zahid, Shahid Bashir, Abul Kalam, Javed Iqbal, Muhammad Abdul Qayyum, S. Wageh, Syed Mustansar Abbas
Summary: The effective diffusion-controlled performance of the SIB anode, CoxTi1-xO2/CNTs, offers high reversible sodium uptake. Increasing the mass ratio of Co atoms in the TiO2 lattice shifts the mechanism from diffusive charge contribution to capacitive charge contribution. The partial amorphization of the crystalline TiO2 and attenuation of the crystal lattice reflect the electrodes' ability for high reversible sodium uptake. The synchronous effect of CNTs and Co loading enhances porosity and multiple conducting channels, favoring high sodium storage and stability.
JOURNAL OF ALLOYS AND COMPOUNDS
(2022)
Article
Mechanics
G. Barbero, L. R. Evangelista, P. Tilli
Summary: The Poisson-Nernst-Planck (PNP) diffusional model is widely used to study the electrochemical impedance response of insulators with ionic impurities. Deviations from the model predictions in the low frequency region are usually attributed to interfacial properties. This study provides a rigorous mathematical analysis of the low-frequency behavior of the model, suggesting that differences in diffusion coefficients of ions may be a key factor in these deviations.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2021)
Article
Materials Science, Multidisciplinary
P. Zavitsanos, X. Zotos
Summary: The proposed model accounts for the relationship between magnetic and phononic transport, offering a new interpretation for experimental results and highlighting the ballistic character of magnetic transport.
Article
Mathematics, Applied
Jasper Juchem, Amelie Chevalier, Kevin Dekemele, Mia Loccufier
Summary: This paper introduces a novel FOPFDD model which incorporates a Fractional Diffusive Delay term for accurate modeling of delay dominant systems. The model is generalized for any real number alpha in the interval [0, 1[, with a special focus on the case of alpha = 0.5 for distributed diffusion systems. The FOPFDD model demonstrates superior accuracy in tracking frequency response functions and mimicking time responses of complex systems.
FRACTIONAL CALCULUS AND APPLIED ANALYSIS
(2021)
Article
Physics, Multidisciplinary
Alexander P. Antonov, Artem Ryabov, Philipp Maass
Summary: This study shows that solitons can be generated through driven overdamped Brownian dynamics of hard spheres in periodic potentials at high densities. These solitons appear as periodic sequences of different particle assemblies in the limit of zero noise and give rise to particle currents even at low temperatures.
PHYSICAL REVIEW LETTERS
(2022)
Article
Mathematics, Applied
Q. I. A. N. G. DU, Z. H. Zhou
Summary: The aim of this paper is to study a simple nonlocal-in-time dynamic system for modeling complex diffusive regimes in heterogeneous media. The model uses a nonlocal operator with a finite memory effect encoded through a kernel function. It captures the crossover between initial sub-diffusion and long time normal diffusion, demonstrating its effectiveness in such capture.
INTERNATIONAL JOURNAL OF NUMERICAL ANALYSIS AND MODELING
(2023)
Article
Physics, Applied
Kazuaki Kobayashi, Hirokazu Takaki, Masato Shimono, Nobuhiko Kobayashi, Kenji Hirose
Summary: Various nanostructured TMN(001) dot/MgO(001) superlattices were investigated to determine their relaxed structures and electronic properties, revealing that band gap values, DOS curves, and other electronic properties vary with changing dot shape and substrate size. Most band gap values, corrected using a generalized density-functional theory, showed improvement.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Review
Chemistry, Multidisciplinary
Shohei Kumagai, Hiroyuki Ishii, Go Watanabe, Craig P. Yu, Shun Watanabe, Jun Takeya, Toshihiro Okamoto
Summary: Organic semiconductors (OSCs) have potential applications in flexible and printed electronic devices, but the practical use of Organic thin-film transistors (OTFTs) is limited by lower carrier mobilities. N-type OSCs lag behind p-type OSCs in carrier mobility due to difficulties in achieving compatibility between aggregated structures and electron affinity. Rational molecular design principles are still needed for high-end device applications.
ACCOUNTS OF CHEMICAL RESEARCH
(2022)
Article
Physics, Applied
Hiroyuki Ishii, Naotaka Kasuya, Nobuhiko Kobayashi, Kenji Hirose, Shohei Kumagai, Shun Watanabe, Jun Takeya
Summary: This study investigates the effects of ionic liquids on the electronic states of organic semiconductor monolayers, revealing that hole doping increases photo-absorption energy while an external field decreases it. The calculations provide useful information for understanding the experimentally observed wavelength shift in photo-absorption spectra.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Masato Iwasawa, Shinnosuke Kobayashi, Masahiro Sasaki, Yuri Hasegawa, Hiroyuki Ishii, Fumihiko Matsui, Satoshi Kera, Yoichi Yamada
Summary: In this study, we applied photoemission tomography (PT) to a unique one-dimensional row structure of a picene multilayer. We successfully deconvoluted the photoelectron momentum maps of three frontier orbitals of picene and determined the molecular orientation in the multilayer. This research marks an important step towards the wide-range utilization of PT technique.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Physics, Applied
Kazuaki Kobayashi, Hirokazu Takaki, Masato Shimono, Hiroyuki Ishii, Nobuhiko Kobayashi, Kenji Hirose, Naohito Tsujii, Takao Mori
Summary: In this study, thin films of Fe2VAl, Fe2VAl/Si, and a related compound were studied using the total energy pseudopotential method. The results showed that these films exhibit ferromagnetic properties with large and enhanced magnetic moments.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Craig P. Yu, Shohei Kumagai, Tomokatsu Kushida, Masato Mitani, Chikahiko Mitsui, Hiroyuki Ishii, Jun Takeya, Toshihiro Okamoto
Summary: This study demonstrates the influence of occupied molecular orbitals on charge transport in high-performance organic semiconductors. A novel molecular design is introduced to induce more pronounced mixed-orbital charge transport, leading to a high hole mobility.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2022)
Article
Chemistry, Physical
Haruki Sato, Syed A. Abd Rahman, Yota Yamada, Hiroyuki Ishii, Hiroyuki Yoshida
Summary: The authors employed angle-resolved low-energy inverse photoelectron spectroscopy to reveal the LUMO band structure of pentacene and proposed an improved polaron model to explain the phenomenon of bandwidth reduction. The results demonstrate that electron mobility in high-mobility organic semiconductors is limited by polaron formation.
Article
Nanoscience & Nanotechnology
William Bodeau, Kaisei Otoge, Wenchang Yeh, Nobuhiko P. Kobayashi
Summary: Selective area crystallization of nonsingle-crystal copper(II) oxide to single-crystal copper(I) oxide was achieved using a chevron-shaped laser beam, while a Gaussian-beam profile resulted in polycrystal thin films. The transition from nonsingle-crystal to single-crystal phase was identified by electron back scattering diffraction and Raman spectroscopy. The experimental findings were supported by a theoretical assessment based on a cellular automaton model, which explained the success of the chevron-beam profile in producing a single crystal compared to the Gaussian-beam profile.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Chemistry, Physical
John W. Koster, Soren A. Tornoe, Nobuhiko P. Kobayashi, Donald C. Potts
Summary: By using high electrical current densities and consumable graphite rod-shaped electrodes, the chlorine evolving reaction (CER) can be suppressed during seawater electrolysis, leading to increased hydrogen production. This approach offers a practical means to reduce CER and enhance hydrogen production, providing environmental and economic incentives.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Physics, Applied
Kazuaki Kobayashi, Hirokazu Takaki, Masato Shimono, Hiroyuki Ishii, Nobuhiko Kobayashi, Kenji Hirose, Takao Mori
Summary: The electronic, lattice, and magnetic properties of CoSb3, Cr-doped CoSb3, and related compound thin films were calculated using the total energy pseudopotential method. Three slab structures, symmetric, asymmetric, and unusual, were considered in a periodically repeated vacuum region and slab. The magnetic moment of doped Cr atom is large in all Cr-doped cases, and the magnetic moments of several Co atoms are enhanced in the asymmetric and unusual cases. The calculation results indicate that most thin films exhibit ferromagnetic electronic states and are energetically more favorable than nonmagnetic cases.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Multidisciplinary
Craig P. Yu, Shohei Kumagai, Michitsuna Tsutsumi, Tadanori Kurosawa, Hiroyuki Ishii, Go Watanabe, Daisuke Hashizume, Hiroki Sugiura, Yukio Tani, Toshihiro Ise, Tetsuya Watanabe, Hiroyasu Sato, Jun Takeya, Toshihiro Okamoto
Summary: This study reports an asymmetric molecular design approach to improve the solubility and solution-processability of benzo[de]isoquinolino[1,8-gh]quinolinetetracarboxylic diimide (BQQDI), while maintaining its excellent charge transport properties, resulting in materials with high electron mobility and large-area continuous single-crystalline thin films.
Article
Chemistry, Multidisciplinary
Yoshitaka Shingaya, Hirokazu Takaki, Nobuhiko Kobayashi, Masakazu Aono, Tomonobu Nakayama
Summary: The study found that tungsten oxide nanorods significantly enhance Raman scattering, which can be attributed to their specific crystal structure. Raman mapping was performed on dispersed nanorods with different adsorbed molecules on a silicon substrate, and it was observed that the Raman images of different molecules were completely distinct, indicating the detection of very few molecules at the single-molecule level.
Article
Engineering, Electrical & Electronic
Muhammad Umair Khan, Chaudhry Muhammad Furqan, Jungmin Kim, Sobia Ali Khan, Qazi Muhammad Saqib, Mahesh Y. Chougale, Rayyan Ali Shaukat, Moon Hee Kang, Nobuhiko P. Kobayashi, Jinho Bae, Hoi-Sing Kwok
Summary: This study focuses on the material and design concept to achieve a one-directional engineered resistive switching memory device to reduce crosstalk effect for electronic synapses. The asymmetric multistate resistive switching behavior and synaptic spike-rate-dependent plasticity and spike-timing-dependent plasticity were validated through simulation and experiments.
ACS APPLIED ELECTRONIC MATERIALS
(2022)