²H-NMR study of molecular reorientation of D₂O confined into the slit-shaped micropores of activated carbon fiber

The version of record of this article, first published in Adsorption, is available online at Publisher’s website: https://doi.org/10.1007/s10450-023-00433-8Herein, the reorientation of heavy water (D2O) molecules adsorbed in the slit-type micropores of activated carbon fibers is investigated using the 2H-nuclear magnetic resonance technique. The rotational correlation times (τ c) of D2O are evaluated from the 2H spin–lattice relaxation time (T 1). The obtained τ c values are significantly influenced by both the pore-filling ratio (ϕ) and temperature, thus suggesting that the adsorption of D2O into activated carbon fibers (ACF) effectively influences the reorientation of the D2O molecules within the ACF. The reorientational motion of D2O is examined by the extended jump model. According to this model, the nanoconfinement effect, which results from the reduction in free volume around D2O, is attributed to the transition-state excluded volume effect, whereas the effect of hydrogen bonding between the D2O and surface functional groups is attributed to the transition-state hydrogen bonding effects. Furthermore, the dependence of τ c on ϕ is explained by the chemical exchange between the pore surface adsorption sites and the central space of the pore. Thus, the dynamic behavior of adsorbed D2O molecules reveals the mechanism of D2O adsorption into the ACF micropores

Marine Snow Removal Benchmarking Dataset

This paper introduces a new benchmarking dataset for marine snow removal of underwater images. Marine snow is one of the main degradation sources of underwater images that are caused by small particles, e.g., organic matter and sand, between the underwater scene and photosensors. We mathematically model two typical types of marine snow from the observations of real underwater images. The modeled artifacts are synthesized with underwater images to construct large-scale pairs of ground truth and degraded images to calculate objective qualities for marine snow removal and to train a deep neural network. We propose two marine snow removal tasks using the dataset and show the first benchmarking results of marine snow removal. The Marine Snow Removal Benchmarking Dataset is publicly available online.Comment: APSIPA ASC 2023, Taipei, Taiwan, Nov. 202

Segmental isotopic labeling of a 140 kDa dimeric multi-domain protein CheA from Escherichia coli by expressed protein ligation and protein trans-splicing

Segmental isotopic labeling is a powerful labeling tool to facilitate NMR studies of larger proteins by not only alleviating the signal overlap problem but also retaining features of uniform isotopic labeling. Although two approaches, expressed protein ligation (EPL) and protein trans-splicing (PTS), have been mainly used for segmental isotopic labeling, there has been no single example in which both approaches have been directly used with an identical protein. Here we applied both EPL and PTS methods to a 140 kDa dimeric multi-domain protein E. coli CheA, and successfully produced the ligated CheA dimer by both approaches. In EPL approach, extensive optimization of the ligation sites and the conditions were required to obtain sufficient amount for an NMR sample of CheA, because CheA contains a dimer forming domain and it was not possible to achieve high reactant concentrations (1–5 mM) of CheA fragments for the ideal EPL condition, thereby resulting in the low yield of segmentally labelled CheA dimer. PTS approach sufficiently produced segmentally labeled ligated CheA in vivo as well as in vitro without extensive optimizations. This is presumably because CheA has self-contained domains connected with long linkers, accommodating a seven-residue mutation without loss of the function, which was introduced by PTS to achieve the high yield. PTS approach was less laborious than EPL approach for the routine preparation of segmentally-isotope labeled CheA dimer. Both approaches remain to be further developed for facilitating preparations of segmental isotope-labelled samples without extensive optimizations for ligation. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10858-012-9628-3) contains supplementary material, which is available to authorized users

Nucleation process in the Burridge-Knopoff model of earthquakes

Nucleation process of the one-dimensional Burridge-Knopoff model of earthquakes obeying the rate- and state-dependent friction law is studied both analytically and numerically. The properties of the nucleation dynamics, the nucleation lengths and the duration times are examined together with their continuum limits.Comment: Title changed, one figure (previous Fig.2) omitted, several references (new Refs.5-8,21,24-28) added, and two eqs. (new eqs.1,5) added. Text expanded considerably, especially the part explaining the relation of the model to the elastic continuum model. To appear in Europhys. Letter