Femtosecond laser driven high-flux highly collimated MeV-proton beam

金沢大学先端科学・社会共創推進機構Highlly collimated energetic protons whose energies are up to 4 MeV are generated by an intense femtosecond Titanium Sappheire laser pulse interacting with a 7.5, 12.5, and 25 μm-thick Polyimide tape target and 5 μm-thick copper target. We find no clear difference on the proton spectra from 7.5, 12.5, and 25 μm Polyimide tape target. The highest conversion efficiency from laser energy into protons of ∼3% is observed with a 7.5 μm thick Polyimide target. The quality of the proton beam is good enough to obtain a clear projection image of a mesh having 10 μm line and space structure, installed into the passage of the beam. We obtain clear vertical lines on the proton intensity profiles from the copper target, which are considered to be transferred from the surface of the copper target. From it, we can restrict the size of the proton emitting region to be ∼20μm. © 2008 American Institute of Physics.Embargo Period 12 month

The Interplay of Family Socioeconomic Status, Parental Engagement, and Maternal Employment on Vocabulary Development in Korean Children

This study aimed to investigate the intricate relationship between socio-economic status (SES) and language development in Korean children under 3 years old. Specifically, it sought to understand how SES influences language development and explored the interconnections among SES, parent-child interactions (specifically through play and book reading), maternal employment, and children's vocabulary scores within the context of Korean parenting culture. Data were collected from 348 mothers of children aged 8–36 months (168 girls; mean age = 20 months 5 days, SD = 7 months and 7 days). Language development was assessed using the Korean version of the MacArthur-Bates Communication Development Index (K-CDI), and parental play frequency, duration, and book-reading frequency were obtained through a questionnaire. We used structural equation modeling to analyze the impact of SES on vocabulary outcomes, examining mediating connections with parental play and book-reading frequency, as well as children’s vocabulary skills. Additionally, we compared variables (SES, play and book-related factors, and K-CDI scores) between working mothers and stay-at-home mothers. The findings indicated that SES significantly predicted vocabulary size, but this influence was fully mediated by parental play frequency, play duration, and book-reading frequency. Interestingly, maternal work status showed no significant impact on children's vocabulary skills, and there were no differences in play frequency, play duration, or book reading frequency despite higher SES among working mothers. The mitigated role of maternal work status on children’s vocabulary skills, despite the differences in their SES, underscores the importance of parent-child interactions, particularly shared book reading, in vocabulary development when these interactions were considered

Localization of Sensor Nodes in Underwater Acoustic Sensor Networks Using Two Reference Points

Abstract — Underwater acoustic sensor networks (UWASN) is being actively researched for its broad spectrum of potential applications. Particularly, submarine or whale tracking can be greatly leveraged by UWASN. These applications require the positions of sensor nodes are determined a priori, but node mobility inherent to underwater environments makes it difficult to employ existing localization methods. In this paper, we propose a novel localization scheme that minimizes the influence of node mobility. We evaluate our method analytically, and show that it performs robustly in various network settings and environment. I

Single-step-fabricated perovskite quantum dot photovoltaic absorbers enabled by surface ligand manipulation

Lead halide perovskite colloidal quantum dots (PQDs) are receiving great interest in emerging photovoltaics because of their excellent photovoltaic properties and the room-temperature processability without a thermal annealing step. Conductive thick PQD absorbers reported to date have been fabricated via multiple-step layer-by-layer deposition based on solid-state ligand exchange; however, this approach requiring a lot of processing time and cost is not suitable for the mass production. Thus, a single-step fabrication approach of conductive thick PQD absorbers should be devised. Herein, we demonstrate that conductive thick CsPbI3-PQD absorbers can be fabricated via a single-step process based on the surface ligand manipulation and employed in efficient PQD solar cells. We find that the conventional ethyl acetate-based post-treatment significantly removes long-chain ligands of the unexchanged PQDs (UN-PQDs) and cause film delamination of thick UN-PQD solids because of drastic volume shrinkage. Thus, we employ the methyl acetate-based post-treatment using phenethylammonium acetate (PEAOAc) to replace both long-chain oleate and oleylammonium within thick UN-PQD solids with short-chain PEA and OAc ligands without film delamination. To further reduce long-chain ligands within the resultant PQD solids, we also employ the PQDs prepared via a solution-phase ligand exchange (SPLE-PQDs) using the phenethylammonium iodide. Furthermore, we perform various spectroscopic measurements, including Fourier-transform infrared, nuclear magnetic resonance, and X-ray photoelectron spectroscopy, to quantitatively analyze the surface chemistry and ligands of PQDs. Consequently, CsPbI3-PQD solar cells, fabricated via a single-step process using SPLE-PQDs and PEAOAc post-treatment, show improved power conversion efficiency (13.7%) compared to that of the UN-PQD device (12.1%). © 2022 Elsevier B.V.FALS

NOx Emissions from Euro 5 and Euro 6 Heavy-Duty Diesel Vehicles under Real Driving Conditions

Despite the strengthening of vehicle emissions standards and test methods, nitrogen oxide (NOx) emissions from on-road mobile sources are not being notably reduced. The introduction of real driving emission (RDE) regulations is expected to reduce the discrepancy between emission regulations and actual air pollution. To analyze the effects of RDE regulations on heavy-duty diesel vehicles, pollutants emitted while driving were measured using a portable emission measurement system (PEMS) for Euro 5 and Euro 6 vehicles, which were produced before and after RDE regulations, respectively. NOx emissions were compared as a function of emissions allowance standards, gross vehicle weight (GVW), average vehicle speed, and ambient temperature. NOx emissions from Euro 6 vehicles were found to be low, regardless of GVW; emissions from both vehicular categories increased with a decline in the average speed. To reflect real road driving characteristics more broadly in the RDE test method for heavy-duty vehicles, it is necessary to consider engine power, which is a criterion for classifying effective sections, in the moving average window (MAW) analysis method, as well as including cold start conditions