257 research outputs found
Effect of NaBH4 on properties of nanoscale zero-valent iron and its catalytic activity for reduction of p-nitrophenol
International audienceThe reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) by nanoscale zero-valent iron (NZVI)/NaBH4 system in an oxygen environment was studied by means of liquid chromatography, spectroscopy (vibration and X-ray photoelectron), solid analyses (transmission electron microscopy and X-ray diffraction) and density functional theory (DFT) calculations. Addition of NaBH4 into NZVI suspension showed the disintegration of NZVI (60-100 nm), resulting in the formation of much smaller particles (15-40 nm) due to the chemical etching of outermost surfaces (i.e., magnetite). Interestingly, complete reduction of p-NP and high conversion efficiency of p-AP (> 98%) were observed in NZVI/NaBH4 system even after four recycling which is quite comparable with widely used noble metallic catalysts. Surface analysis confirmed that NaBH4 can prevent the oxidation of NZVI surface, leading to the continuous reduction of p-NP in oxygen environments. Experimental results and DFT calculations suggested that not only the formation of smaller NZVI but also thermodynamic preferences for reduction of p-NP on outermost surfaces of NZVI (i.e. magnetite) may significantly affect the reduction process of p-NP in NZVI/NaBH4 system. These novel findings can promote the development of new NZVI technologies which can be used for wastewater reductive treatment in oxygen environment
Measuring Haptic Experience: Elaborating the HX model with scale development
If an author previously posted their submitted version of the article in any of the following locations, he or she will need to replace the submitted version with the accepted version and add the IEEE copyright notice (© 2021 IEEE). When the article is published, the posted version should be updated with a full citation to the original IEEE publication, including DOI. No other changes may be made to the accepted article.Designers increasingly employ haptic feedback with the aim to improve user experience (UX). Designers and researchers currently use qualitative methods or demos for feedback, but neither approach scales to large studies or remote work. We build upon the recent Haptic Experience (HX) model and report on progress towards measuring the five constructs for designing haptic experiences: Harmony, Expressivity, Autotelics, Immersion, and Realism. We describe initial findings from scale development, specifically, from item generation (N=23) and exploratory factor analysis (N=261). Our results provide initial evidence that vibrotactile experiences are effectively modeled by five factors, enriched description of each factor, and guidelines for quantitatively measuring HX.NSERC Discovery Gran
Iron-Fur complex suppresses the expression of components of the cyclo-(Phe-Pro)-signaling regulatory pathway in Vibrio vulnificus
In the human pathogen Vibrio vulnificus, the quorum-sensing (QS) signal molecule cyclo-(L-phenylalanine-L-proline) (cFP) plays a critical role in triggering a signaling pathway involving the components LeuO-vHUαβ-RpoS-KatG via the membrane signal receptor ToxR. In this study, we investigated the impact of iron on the expression of these signaling components. We found that the transcription of the membrane sensor protein ToxR was not significantly affected by Fur-iron. However, Fur-iron repressed the transcription of genes encoding all the downstream cytoplasmic components in this pathway by binding to the upstream regions of these genes. Consequently, the expression of genes regulated by the alternative sigma factor RpoS, as well as the resistance to hydrogen peroxide conferred by KatG, were repressed. Additionally, we observed that in Vibrio cholerae, genes dependent on ToxR showed higher expression levels in a fur-deletion mutant compared to the wild type. These findings indicate that iron, in association with Fur, represses virtually all the cytoplasmic components responsible for the ToxR-dependent cFP-signaling pathways in these two pathogenic Vibrio species. This study, along with our previous reports demonstrating the repression of components involved in AI-2 dependent QS signaling by Fur-iron, highlights the crucial role of iron in quorum-sensing regulation, which is closely associated with the pathogenicity of this human pathogen
Comprehensive MicroRNAome Analysis of the Relationship Between Alzheimer Disease and Cancer in Double-Knockout Mice
Purpose Presenilins are functionally important components of γ-secretase, which cleaves a number of transmembrane proteins. Manipulations of PSEN1 and PSEN2 have been separately studied in Alzheimer disease (AD) and cancer because both involve substrates of γ-secretase. However, numerous clinical studies have reported an inverse correlation between AD and cancer. Interestingly, AD is a neurodegenerative disorder, whereas cancer is characterized by the proliferation of malignant cells. However, this inverse correlation in the PSEN double-knockout (PSEN dKO) mouse model of AD has been not elucidated, although doing so would shed light onto the relationship between AD and cancer. Methods To investigate the inverse relationship of AD and cancer under conditions of PSEN loss, we used the hippocampus of 7-month-old and 18-month-old PSEN dKO mice for a microRNA (miRNA) microarray analysis, and explored the tumorsuppressive or oncogenic role of differentially-expressed miRNAs. Results The total number of miRNAs that showed changes in expression level was greater at 18 months of age than at 7 months. Most of the putative target genes of the differentially-expressed miRNAs involved Cancer pathways. Conclusions Based on literature reviews, many of the miRNAs involved in Cancer pathways were found to be known tumorsuppressive miRNAs, and their target genes were known or putative oncogenes. In conclusion, the expression levels of known tumor-suppressive miRNAs increased at 7 and 18 months, in the PSEN dKO mouse model of AD, supporting the negative correlation between AD and cancer
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iPSC Modeling of Presenilin1 Mutation in Alzheimer's Disease with Cerebellar Ataxia.
Disease modeling of Alzheimer's disease (AD) has been hampered by the lack of suitable cellular models while animal models are mainly based on the overexpression of AD-related genes which often results in an overemphasis of certain pathways and is also confounded by aging. In this study, we therefore developed and used induced pluripotent stem cell (iPSC) lines from a middle-aged AD patient with a known presenilin 1 (PSEN1) mutation (Glu120Lys; PS1-E120K) and as a control, an elderly normal subject. Using this approach, we demonstrated that the extracellular accumulation of Aβ was dramatically increased in PS1-E120K iPSC-derived neurons compared with the control iPSC line. PS1-E120K iPSC-derived neurons also exhibited high levels of phosphorylated tau, as well as mitochondrial abnormalities and defective autophagy. Given that the effect of aging is lost with iPSC generation, these abnormal cellular features are therefore indicative of PSEN1-associated AD pathogenesis rather than primary changes associated with aging. Taken together, this iPSC-based approach of AD modeling can now be used to better understand AD pathogenesis as well as a tool for drug discovery.This work was supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (HI14C2746) and a grant (2016-0588) from the Asan Institute for Life Sciences
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