5578 research outputs found
Sort by
Knockout of Brca1-interacting factor Ola1 in female mice induces tumors with estrogen suppressible centrosome amplification
No full textObg-like ATPase 1 (OLA1) is a binding protein of Breast cancer gene 1 (BRCA1), germline pathogenic variants of which cause hereditary breast cancer. Cancer-associated variants of BRCA1 and OLA1 are deficient in the regulation of centrosome number. Although OLA1 might function as a tumor suppressor, the relevance of OLA1 deficiency to carcinogenesis is unclear. Here, we generated Ola1 knockout mice. Aged female Ola1+/− mice developed lymphoproliferative diseases, including malignant lymphoma. The lymphoma tissues had low expression of Ola1 and an increase in the number of cells with centrosome amplification. Interestingly, the proportion of cells with centrosome amplification in normal spleen from Ola1+/− mice was higher in male mice than in female mice. In human cells, estrogen stimulation attenuated centrosome amplification induced by OLA1 knockdown. Previous reports indicate that prominent centrosome amplification causes cell death but does not promote tumorigenesis. Thus, in the current study, the mild centrosome amplification observed under estrogen stimulation in Ola1+/− female mice is likely more tumorigenic than the prominent centrosome amplification observed in Ola1+/− male mice. Our findings provide a possible sex-dependent mechanism of the tumor suppressor function of OLA1.journal articl
The XRISM first-light observation: Velocity structure and thermal properties of the supernova remnant N 132D
No full textWe present an initial analysis of the X-Ray Imaging and Spectroscopy Mission ( XRISM) first-light observation of the supernova remnant ( SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band,
which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of σv ∼ 450 km s −1 . However, the Fe He α lines are substantially broadened with σv ∼ 1670 km s −1 . This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He α emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be −10 0 0 ≲ Vrs ( km s −1 ) ≲ 3300 ( in the observer frame) . We also find that Fe Ly α emission is redshifted with a bulk velocity of ∼ 890 km s −1 , substantially larger than the radial velocity of the local interstellar medium
surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.journal articl
Search for Baryon-Number-Violating Processes in B- Decays to the Ξ ¯ c0 Λ ¯ c- Final State
No full textjournal articl
A Study of the Conceptual Structure of Growth Mindsets and Their Impact on Self‐Improvement Motivation
No full textThis study examined the conceptual structure and motivational effects of growth mindsets based on the perspective of character strengths. An internet survey was conducted with 1,000 workers (500 males and 500 females; age range 20–59 years, M = 40.1 years, SD = 10.7 years). Participants were presented with 25 strengths (i.e., intelligence and 24 character strengths) and were asked to rate their perceived competence, growth mindset, and improvement intention for each strength. The exploratory factor analyses on perceived competence, growth mindset, and improvement intention identified five common factors: wisdom, willpower, temperance, transcendence, and groupness. Moreover, regression analyses indicated that a growth mindset was more strongly related to improvement intention than perceived competence. Furthermore, regression analyses found domain-specific effects of growth mindsets on improvement intention. Thus, the intention to improve a particular strength was more closely related to that particular growth mindset than to other growth mindsets. The theoretical and educational implications are aired in the discussion section.journal articl
Distinguishing the XUV-induced Coulomb explosion dynamics of iodobenzene using covariance analysis
No full textThe primary and secondary fragmentation dynamics of iodobenzene following its ionization at
120 eV were determined using three-dimensional velocity map imaging and covariance
analysis. Site-selective iodine 4d ionization was used to populate a range of excited polycationic
parent states, which primarily broke apart at the carbon-iodine bond to produce I+ with phenyl
or phenyl-like cations (CnHx+ or CnHx 2+, with n = 1–6 and x = 1–5). The molecular
products were produced with varying degrees of internal excitation and dehydrogenation,
leading to stable and unstable outcomes. This further allowed the secondary dynamics of
C6Hx 2+ intermediates to be distinguished using native-frame covariance analysis, which
isolated these processes in their own centre-of-mass reference frames. The mass resolution of
the imaging mass spectrometer used for these measurements enabled the primary and secondary
reaction channels to be specified at the level of individual hydrogen atoms, demonstrating the
ability of covariance analysis to comprehensively measure the competing fragmentation
channels of aryl cations, including those involving intermediate steps.journal articl
Exploring the ultrafast and isomer-dependent photodissociation of iodothiophenes via site-selective ionization
No full textC–I bond extension and fission following ultraviolet (UV, 262 nm) photoexcitation of 2- and 3-iodothiophene is studied using ultrafast time-resolved extreme ultraviolet (XUV) ionization in conjunction with velocity map ion imaging. The photoexcited molecules and eventual I atom products are probed by site-selective ionization at the I 4d edge using intense XUV pulses, which induce multiple charges initially localized to the iodine atom. At C–I separations below the critical distance for charge transfer (CT), charge can redistribute around the molecule leading to Coulomb explosion and charged fragments with high kinetic energy. At greater C–I separations, beyond the critical distance, CT is no longer possible and the measured kinetic energies of the charged iodine atoms report on the neutral dissociation process. The time and momentum resolved measurements allow determination of the timescales and the respective product momentum and kinetic energy distributions for both isomers, which are interpreted in terms of rival ‘direct’ and ‘indirect’ dissociation pathways. The measurements are compared with a classical over the barrier model, which reveals that the onset of the indirect dissociation process is delayed by ∼1 ps relative to the direct process. The kinetics of the two processes show no discernible difference between the two parent isomers, but the branching between the direct and indirect dissociation channels and the respective product momentum distributions show isomer dependencies. The greater relative yield of indirect dissociation products from 262 nm photolysis of 3-iodothiophene (cf. 2-iodothiophene) is attributed to the different partial cross-sections for (ring-centred) π∗ ← π and (C–I bond localized) σ∗ ← (n/π) excitation in the respective parent isomers.journal articl
Unsymmetrization of 1,8-Dibromonaphthalenes by Acid-Induced Halogen Dance Reaction
No full textA simple and powerful tool for preparing uncommon bromoarenes via the unsymmetrization of a naphthalene ring was developed. The steric repulsion between the peri-bromo groups of 1,8-dibromonaphthalene distorts the naphthalene ring, allowing for nonelectronical activation. Ring distortion facilitates the 1,2-rearrangement of the bromo group, affording 1,7-dibromonaphthalene upon treatment with trifluoromethanesulfonic acid (halogen dance reaction). For 1,4,5,8-tetrabromonaphthalene, stepwise 1,2-rearrangements proceeded successively to furnish 1,3,5,7-tetrabromonaphthalene. Density functional theory calculations suggest that this reaction is initiated by ipso-protonation, with a subsequent 1,2-rearrangement occurring via the bromonium transition state. Utilizing 1,7-dibromonaphthalene, which is characterized by two C–Br bonds arranged at a 60° angle, a unique metal–organic framework comprising a 52-membered ring network was synthesized.journal articl
Highly electron-deficient 1-propyl-3,5-dinitropyridinium: evaluation of electron-accepting ability and application as an oxidative quencher for metal complexes
No full textImpacts of the nitro groups on the electron-accepting and oxidizing abilities of N-propylpyridinium were evaluated quantitatively. A 3,5-dinitro derivative has efficiently quenched emission from photosensitizing Ru(ii) and Ir(iii) complexes owing to the thermodynamically-favored electron transfer to the pyridinium whose LUMO is greatly lowered by the presence of electron-withdrawing nitro groups.journal articl
Revealing the Unusual Mechanism of Mixed Cationic and Anionic Redox in Oxyfluorosulfide Cathode for All-Solid-State Fluoride-Ion Batteries
No full textAll-solid-state fluoride-ion batteries (FIBs) have been considered next-generation energy storage devices because of their high theoretical energy density. However, previously reported metal/metal fluoride active materials suffer from severe degradation due to large volume expansion; consequentially, fluoride-ion-intercalating active materials fail to deliver a high capacity. Here, oxyfluorosulfide Sr2F2Fe2OS2 (SFFOS) with a layer structure is reported as a topotactic fluoride-ion (de)intercalation host. This material delivers a high reversible capacity of more than 340 mAh g–1, which remains well maintained after 20 cycles. The intercalation reaction mechanism for this high and stable capacity is elucidated via X-ray diffraction and fine structure analysis. Wherein both Fe2+/Fe3+ redox and sulfide ion redox are involved in charge compensation during charge/discharge processes, where the sulfide ion redox contributes to the whole voltage range of −1.5 to 1.5 V and Fe2+/Fe3+ redox only contributes from the middle state of charge. Fluoride ions can not only insert into the Sr–S interstitial sites but also combine with Fe cations. Meanwhile, excessive fluoride-ion intercalation leads to the formation of S–S bonds in the SFFOS lattice. These results highlight the oxyfluorosulfides with layer structure as a new class of active materials for constructing high-performance FIBs.journal articl