25 papers · ranked by Valyu relevance
Ebrahim Najafi, Vsevolod Ivanov, Ahmed Zewail, Marco Bernardi
The ultrafast spatial and temporal dynamics of excited carriers are important to understanding the response of materials to laser pulses. Here we use scanning ultrafast electron microscopy to image the dynamics of electrons and holes in silicon after excitation with a short laser pulse. We find that the carriers…
Hugues Berry, Hédi A. Soula
Experimental measurements of the mobility of macromolecules, especially proteins, in cells and their membranes consistently report transient subdiffusion with possibly position-dependent-non-homogeneous-properties. However, the spatiotemporal dynamics of protein mobility when transient subdiffusion is restricted to a…
Anders S. Hansen, Assaf Amitai, Claudia Cattoglio, Robert Tjian + 1 more
Mammalian genomes are enormous. For a DNA-binding protein, this means that the number of non-specific, off-target sites vastly exceeds the number of specific, cognate sites. How mammalian DNA-binding proteins overcome this challenge to efficiently locate their target sites is not known. Here through live-cell…
Qingqing Yin, Yunyun Li, Fabio Marchesoni, Shubhadip Nayak + 1 more
'Pulak K. Ghosh'] Brownian particles suspended in disordered crowded environments often exhibit non-Gaussian normal diffusion (NGND), whereby their displacements grow with mean square proportional to the observation time and non-Gaussian statistics. Their distributions appear to decay almost exponentially according to…
Ignasi Alemany, Jan N Rose, Jérôme Garnier-Brun, Andrew D. Scott + 1 more
'Denis Doorly'] In this paper we present analytical and random walk based solutions to diffusion in semi-permeable layered media with varying diffusivity. We propose a new random walk transit model (hybrid model) based on treating the membrane permeability and the change in diffusion as two infinitesimal separate…
Hédi A Soula, Antoine Coulon, Guillaume Beslon
Background In the classical view, cell membrane proteins undergo isotropic random motion, that is a 2D Brownian diffusion that should result in an homogeneous distribution of concentration. It is, however, far from the reality: Membrane proteins can assemble into so-called microdomains (sometimes called lipid rafts)…
Rui Yan, Kun Chen, Ke Xu
Diffusion properties notably determine the behavior of biomembranes. Here we report the concurrent nanoscale fine-mapping of membrane topography, diffusivity, and packing order in live mammalian cells through a synergy of single-molecule and super-resolution methods. By identifying a bright, lipophilic fluorescence…
Jacopo Bertolotti
Diffusion processes are studied theoretically for the case where the diffusion coefficient is itself a time and position dependent random function. We investigate how inhomogeneities and fluctuations of the diffusion coefficient affect the transport using a perturbative approach, with a special attention to the time…
Lim Heo, Katukurunde Gamage, Gilberto Valdes-Garcia, Lisa J. Lapidus + 1 more
Transient protein-protein interactions occur frequently under the crowded conditions encountered in biological environments, yet they remain poorly understood. Here, tryptophan-cysteine quenching is introduced as an experimental approach that is ideally suited to characterize such interactions between proteins with…
Elliot J. Carr
Mathematically, it takes an infinite amount of time for the transient solution of a diffusion equation to transition from initial to steady state. Calculating a finite transition time, defined as the time required for the transient solution to transition to within a small prescribed tolerance of the steady state…
Valerii M. Sukhorukov, Jürgen Bereiter-Hahn, Andreas Hofmann
Diffusion of inner membrane proteins is a prerequisite for correct functionality of mitochondria. The complicated structure of tubular, vesicular or flat cristae and their small connections to the inner boundary membrane impose constraints on the mobility of proteins making their diffusion a very complicated process.…
M. J. Saxton
Single-particle tracking experiments have measured the distribution of escape times of DNA-binding species diffusing in living cells: CRISPR-Cas9, TetR, and LacI. The observed distribution is a truncated power law. One important property of this distribution is that it is inconsistent with a Gaussian distribution of…
Arthur Chakwizira, Filip Szczepankiewicz, Markus Nilsson
Double diffusion encoding (DDE) makes diffusion MRI sensitive to a wide range of microstructural features, and the acquired data can be analysed using different approaches. Correlation tensor imaging (CTI) uses DDE to resolve three components of the diffusional kurtosis: isotropic, anisotropic, and microscopic…
Raffaele Pastore, Antonio Coniglio, Massimo Pica Ciamarra
One of the most controversial hypotheses for explaining the heterogeneous dynamics of glasses postulates the temporary coexistence of two phases characterized by a high and by a low diffusivity. In this scenario, two phases with different diffusivities coexist for a time of the order of the relaxation time and mix…
Suryoday Prodhan, Samuele Giannini, Linjun Wang, David Beljonne
Raising the distance covered by singlet excitons during their lifetimes to values maximizing light absorption (a few hundred nm) would solve the exciton diffusion bottleneck issue and lift the constraint for fine (~10 nm) phase segregation in bulk heterojunction organic solar cells. In that context, the recent report…
Authors not listed
Conventional directed colloidal assembly enables fabricating complex hierarchical structures using external stimuli like electric fields, but lacks control over the assembly state in time. Chemical reaction networks have been discovered that transiently assemble colloids; however, they have slow dynamics (hrs – days)…
Ignasi Alemany, Jan N. Rose, Jérôme Garnier-Brun, Andrew D. Scott + 1 more
'Denis J. Doorly'] In this paper we present random walk based solutions to diffusion in semi-permeable layered media with varying diffusivity. We propose a novel transit model for solving the interaction of random walkers with a membrane. This hybrid model is based on treating the membrane permeability and the step…
Renat T. Sibatov, V. V. Uchaikin
We continue to develop a new approach to description of charge kinetics in disordered semiconductors. It is based on fractional diffusion equations. This article is devoted to transient processes in structures under dispersive transport conditions. We demonstrate that this approach allows us (i) to take into account…
Achuthan Raja Venkatesh, Kathy H. Le, David M. Weld, Onn Brandman
While inhomogeneous viscosity has been identified as a ubiquitous feature of the cellular interior, its implications for particle mobility and concentration at different length scales have remained unexplored. In this work, we use agent-based simulations of diffusion to investigate how diverse manifestations of…
Authors not listed
Antimicrobial peptides (AMPs) are highly effective broad-spectrum antibiotics, found as components of the immune system in almost all forms of life. It is well established that their primary target is the cell membrane where they are hypothesized to permeabilize the bilayer. However, it is a long-standing question…
Jixin Chen
Predicting the reaction kinetics, that is, how fast a reaction can happen in a solution, is essential information for many processes, such as industrial chemical manufacturing, refining, synthesis and separation of petroleum products, environmental processes in air and water, biological reactions in cells, biosensing…
Spencer Wozniak, Michael Feig
The viscosity and diffusion properties of crowded protein systems were investigated with molecular dynamics simulations of SH3 mixtures with different crowders, and results were compared with experimental data. The simulations accurately reproduced experimental trends across a wide range of protein concentrations…
William R. Holmes
It has long been known that the complex cellular environment leads to anomalous motion of intracellular particles. At a gross level, this is characterized by mean squared displacements that deviate from the standard linear profile. Statistical analysis of particle trajectories has helped further elucidate how different…
Authors not listed
CO hydrogenation is a promising approach for the storage of renewable energy in the form of hydrocarbons via the Fischer-Tropsch synthesis (FTS). Since transient operation of FTS reactors might be necessary and even be beneficial, transient kinetics for a rational catalyst and reactor design are essential. In order to…
Authors not listed
Obtaining quantitative information about residence time behavior (i.e., the residence time distribution function) in realistic experimental systems is oftentimes experimentally challenging and numerically complex. The conventional way is to conduct very simple pulse or step tracer experiments or construct elaborate…