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Significance of Histidine Hydrogen–Deuterium Exchange Mass Spectrometry in Protein Structural Biology
No full textHistidine residues play crucial roles in shaping the function and structure of proteins due to their unique ability to act as both acids and bases. In other words, they can serve as proton donors and acceptors at physiological pH. This exceptional property is attributed to the side-chain imidazole ring of histidine residues. Consequently, determining the acid-base dissociation constant (Ka) of histidine imidazole rings in proteins often yields valuable insights into protein functions. Significant efforts have been dedicated to measuring the pKa values of histidine residues in various proteins, with nuclear magnetic resonance (NMR) spectroscopy being the most commonly used technique. However, NMR-based methods encounter challenges in assigning signals to individual imidazole rings and require a substantial amount of proteins. To address these issues associated with NMR-based approaches, a mass-spectrometry-based method known as histidine hydrogen–deuterium exchange mass spectrometry (His-HDX-MS) has been developed. This technique not only determines the pKa values of histidine imidazole groups but also quantifies their solvent accessibility. His-HDX-MS has proven effective across diverse proteins, showcasing its utility. This review aims to clarify the fundamental principles of His-HDX-MS, detail the experimental workflow, explain data analysis procedures and provide guidance for interpreting the obtained results.journal articl
タスク&アンビエント照明における照度バランスに関する研究（その2）：照明制御方式が定常順応時の容認率に与える影響
No full textThis study reports the influence of lighting control methods on the acceptance rates in the relation between the task illuminance T and the ambient illuminance A in a steady state. Additionally, the visual performance and impression are analyzed. The acceptable A in a steady state under each T is predicted with considering illuminance preference by using a prediction method from the previous report which analyzes the acceptable T in a steady state under each T/A. The commonalities and the differences with the previous report, as well as their causes, are discussed.journal articl
Synthesis of tricarbonylated propargylamine and conversion to 2,5-disubstituted oxazole-4-carboxylates
No full textThe N,O-acetal derived from diethyl mesoxalate (DEMO) undergoes elimination of acetic acid upon treatment with a base, leading to the formation of N-acylimine in situ. Lithium acetylide readily attacks the imino group to afford N,1,1-tricarbonylated propargylamines. When the resulting propargylamine reacts with butyllithium, ring closure occurs between the ethynyl and carbamoyl groups, yielding 2,5-disubstituted oxazole-4-carboxylates. This cyclization also occurs when the propargylamine is heated with ammonium acetate, resulting in double activation.journal articl
Observations of cold-induced vasodilation in persons with spinal cord injuries
No full textSTUDY DESIGN: Acute experimental study.
OBJECTIVES: Cold-induced vasodilation is a local mechanism of protection against frostbite in non-injured persons. We ssessed whether an increase in skin blood flow (SkBF) during local cooling (LC) was observed in individuals with spinal cord injuries (SCIs) and if the response patterns differed between region levels or sites.
SETTING: Laboratory of Wakayama Medical University and the affiliated clinics, Japan.
METHODS: A local cooler device (diameter 4cm) was placed on the chest (sensate) and right thigh (non-sensate) in persons with cervical (SCIC; n = 9) and thoracolumbar SCIs (SCITL; n =9). After the surface temperature under the device was controlled at 33°C for 10min (baseline), LC (−0.045°C/s) was applied and the skin temperature was maintained at 15 and 8°C for 15min of each stage. SkBF (laser Doppler flowmetry) was monitored using a 1-mm needle-type probe inserted into its center.
RESULTS: The percent change in SkBF (%ΔSkBF) on the chest remained unchanged until the end of 15°C stage; thereafter, it increased to a level at least 70% greater than the baseline during the 8°C stage in both groups. The %ΔSkBF on the thigh in both SCIC and SCITL notably increased from 8 and 6min respectively, during the 8°C stage, compared to 1min before the stage; however, it did not exceed the baseline level.
CONCLUSIONS: An increase in SkBF during LC was observed both in the sensate and non-sensate areas in SCIs, although the magnitude was larger in the sensate area.journal articl
Evaluating the IWSLT2023 Speech Translation Tasks: Human Annotations, Automatic Metrics, and Segmentation
No full textHuman evaluation is a critical component in machine translation system development and has received much attention in text translation research. However, little prior work exists on the topic of human evaluation for speech translation, which adds additional challenges such as noisy data and segmentation mismatches. We take first steps to fill this gap by conducting a comprehensive human evaluation of the results of several shared tasks from the last International Workshop on Spoken Language Translation (IWSLT 2023). We propose an effective evaluation strategy based on automatic resegmentation and direct assessment with segment context. Our analysis revealed that: 1) the proposed evaluation strategy is robust and scores well-correlated with other types of human judgements; 2) automatic metrics are usually, but not always, well-correlated with direct assessment scores; and 3) COMET as a slightly stronger automatic metric than chrF, despite the segmentation noise introduced by the resegmentation step systems. We release the collected human-annotated data in order to encourage further investigation.journal articl
Tracking Cavity Formation in Electron Solvation: Insights from X-ray Spectroscopy and Theory
No full textWe present time-resolved X-ray absorption spectra of ionized liquid water and demonstrate that OH radicals, H3O+ ions, and solvated electrons all leave distinct X-ray-spectroscopic signatures. Particularly, this allows us to characterize the electron solvation process through a tool that focuses on the electronic response of oxygen atoms in the immediate vicinity of a solvated electron. Our experimental results, supported by ab initio calculations, confirm the formation of a cavity in which the solvated electron is trapped. We show that the solvation dynamics are governed by the magnitude of the random structural fluctuations present in water. As a consequence, the solvation time is highly sensitive to temperature and to the specific way the electron is injected into water.journal articl
Structure and particle surface analysis of Li<sub>2</sub>S–P<sub>2</sub>S<sub>5</sub>–LiI-type solid electrolytes synthesized by liquid-phase shaking
No full textLi2S–P2S5–LiI-type solid electrolytes, such as Li4PS4I, Li7P2S8I, and Li10P3S12I, are promising candidates for anode layers in all-solid-state batteries because of their high ionic conductivity and stability toward Li anodes. However, few studies have been conducted on their detailed local structure and particle surface state. In this study, Li7P2S8I (Li2S: P2S5:LiI = 3:1:1) solid electrolytes as the chemical composition were synthesized by mechanical milling and liquid-phase shaking, and their local structures were analyzed by transmission electron microscopy. The particle surface states were analyzed by X-ray photoelectron spectroscopy, high-energy X-ray scattering measurements, and neutron total scattering experiments. The results showed that Li7P2S8I solid electrolytes are composed of nanocrystals, such as Li4PS4I, LiI, Li10P3S12I and an amorphous area as the main region, indicating that the crystalline components alone do not form ionic conductive pathways, with both the amorphous and crystalline regions contributing to the high ionic conductivity. Moreover, the ionic conductivity of the crystalline/amorphous interface of the glass-ceramic was higher than that of the Li2S–P2S5–LiI glass. Finally, an organic-solvent-derived stable surface layer, which was detected in the liquid-phase shaking sample, served as one of the factors that contributed to its high stability (which surpassed that of the mechanically milled sample) toward lithium anodes. We expect these findings to enable the effective harnessing of particle surface states to develop enhanced sulfide solid electrolytes.journal articl
Spin dynamics phenomena of a cerium(iii) double-decker complex induced by intramolecular electron transfer
No full textSwitchable spin dynamic properties in single-molecule magnets (SMMs) via an applied stimulus have applications in single-molecule devices. Many SMMs containing heavy lanthanoid ions with strong uniaxial magnetic anisotropy have been reported to exhibit SMM characteristics in the absence of an external magnetic field. On the other hand, SMMs containing light lanthanoid cerium(III) (Ce3+) ions exhibit field-induced slow magnetic relaxation. We investigated the chemical conversion of a diamagnetic Ce4+ ion (4f0) to a paramagnetic Ce3+ ion (4f1) in Ce-phthalocyaninato double-decker complexes (TBA+[Ce(obPc)2]− (1) and TBA+[Ce(Pc)2]− (2)) which exhibit field-induced SMM behaviour due to a 4f1 system. The phthalocyaninato ligands with electron-donating substituents (obPc2− = 2,3,9,10,16,17,23,24-octabutoxyphthalocyaninato) in 1 have a significant effect on the valence state of the Ce ion, which is reflected in its magnetic properties due to the mixed valence state of the Ce ion. Given that Ce double-decker complexes with π-conjugated ligands undergo intramolecular electron transfer (IET) to the Ce ion mixed valence state, characterised by a mixture of 4f0 and 4f1 configurations, we examined the dynamic disorder inherent in IET influencing magnetic relaxation.journal articl
Neural activity related to productive vocabulary knowledge effects during second language comprehension
No full textSecond language learners and educators often believe that improving one’s listening ability hinges on acquiring an extensive vocabulary and engaging in thorough listening practice. Our previous study suggested that listening comprehension is also impacted by the ability to produce vocabulary. Nevertheless, it remained uncertain whether quick comprehension could be attributed to a simple acceleration of processing or to changes in neural activity. To identify neural activity changes during sentence listening comprehension according to different levels of lexical knowledge (productive, only comprehensive, uncomprehensive), we measured participants’ electrical activity in the brain via electroencephalography (EEG) and conducted a time-frequency-based EEG power analysis. Additionally, we employed a decoding model to verify the predictability of vocabulary knowledge levels based on neural activity. The decoding results showed that EEG activity could discriminate between listening to sentences containing phrases that include productive knowledge and ones without. The positive impact of productive vocabulary knowledge on sentence comprehension, driven by distinctive neural processing during sentence comprehension, was unequivocally evident. Our study emphasizes the importance of productive vocabulary knowledge acquisition to enhance the process of second language listening comprehension.journal articl
