Oxygen species adsorbed on ultraviolet-irradiated magnesium oxide

Ito, Tairo; Kato, M.; Toi, Keio; Shirakawa, Toshiaki; Ikemoto, Isao; Tokuda, Taneki

doi:10.1039/f19858102835

Cited by 46 publications

(26 citation statements)

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“…These interactions can generate various intermediates, such as superoxide (O 2 − ), peroxide (O 2 2− ) and O − species, before reducing these intermediates to lattice oxygen (O 2− ) 34 . It is believed that UV radiation can preferentially facilitate the formation of superoxides (chemically adsorbed oxygen) through the reaction of oxygen molecules with electrons trapped on the surface 35 . To verify this hypothesis, XPS studies were conducted using the same GDC sample without and with UV radiation exposure, as presented in Figures S5 and S3, respectively.…”

Section: Resultsmentioning

confidence: 99%

Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

Younis

Chu

2015

Sci Rep

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Further progress in high-performance microelectronic devices relies on the development of novel materials and device architectures. However, the components and designs that are currently in use have reached their physical limits. Intensive research efforts, ranging from device fabrication to performance evaluation, are required to surmount these limitations. In this paper, we demonstrate that the superior bipolar resistive switching characteristics of a CeO2:Gd-based memory device can be manipulated by means of UV radiation, serving as a new degree of freedom. Furthermore, the metal oxide-based (CeO2:Gd) memory device was found to possess electrical and neuromorphic multifunctionalities. To investigate the underlying switching mechanism of the device, its plasticity behaviour was studied by imposing weak programming conditions. In addition, a short-term to long-term memory transition analogous to the forgetting process in the human brain, which is regarded as a key biological synaptic function for information processing and data storage, was realized. Based on a careful examination of the device’s retention behaviour at elevated temperatures, the filamentary nature of switching in such devices can be understood from a new perspective.

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Section: Resultsmentioning

confidence: 99%

Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

Younis

Chu

2015

Sci Rep

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“…In order to mimic the in vivo conditions under which the nanoparticles are used and make the results comparable to other in vitro studies, MgO nanoparticles were sterilized in a glass container via heating at 200°C in an oven for 1 h prior to immersion in physiologically relevant solutions. MgO cannot be disinfected through UV irradiation because the UV affects the surface chemistry of the MgO particles by causing adsorption of O 2 and production of superoxide ions (Ito et al 1985;Yanagisawa 1981). MgO is also recommended not to be autoclaved for sterilization because of its hydroscopic nature.…”

Section: Preparation Of Mgo and Mg(oh) 2 Nanoparticlesmentioning

confidence: 99%

Dissociation of magnesium oxide and magnesium hydroxide nanoparticles in physiologically relevant fluids

et al. 2018

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Magnesium oxide (MgO) and hydroxide [Mg(OH) 2 ] are conventionally considered insoluble in water and stable at high temperatures. However, in this study, we found significant dissociation of MgO and Mg(OH) 2 into ions when they were immersed in different physiologically relevant solutions in the form of 20nm and 10-nm nanoparticles respectively, under standard cell culture conditions in vitro, i.e., a 37°C, 5% CO 2 /95% air, sterile, humidified environment. The change in Mg 2+ ion concentrations and pH measured in the physiologically relevant solutions (e.g., Dulbecco's modified Eagle's Medium (DMEM), simulated body fluid (SBF), relevant chloride solutions, and deionized water) confirmed their dissociation. Possible mechanisms and contributing factors for dissociation of MgO and Mg(OH) 2 nanoparticles were discussed. The evidence suggests that nucleophilic substitution of OH − by Cl − in Mg(OH) 2 is energetically unfavorable and it is more likely that Cl − plays a role in the stabilization of intermediate forms of MgO and Mg(OH) 2 as it dissociates. The pH and buffering capability of the immersion solutions might have played the most significant role in dissociation of these nanoparticles when compared with the roles of chloride (Cl − ), proteins, and different buffering agents. This article provided the first evidence on the dissociation of MgO and Mg(OH) 2 nanoparticles in physiologically relevant conditions and elucidated possible factors contributing to the observed behaviors of these nanoparticles in vitro, which is important for their potential medical applications in vivo. Keywords Magnesium oxide (MgO) nanoparticles . Magnesium hydroxide [Mg(OH) 2 ] nanoparticles . Biofluids . Dulbecco's modified Eagle's Medium (DMEM) . Simulated body fluid (SBF) . HEPES buffer . Chloride (Cl − ) solutions

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“…The MgO nanoparticles for BMSC and bacterial cultures were sterilized through heating at 200°C in an oven for one hour. MgO cannot be sterilized through UV irradiation because the UV affects the surface chemistry of the MgO particles by causing adsorption of O 2 and production of superoxide ions [25,26]. MgO nanoparticles were sterilized prior to characterization so that the particles would be in the same condition during characterization as they were in in vitro experiments.…”

Section: Preparation and Characterization Of Mgo Nanoparticlesmentioning

confidence: 99%

Concentration-dependent behaviors of bone marrow derived mesenchymal stem cells and infectious bacteria toward magnesium oxide nanoparticles

2016

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This article reports the quantitative relationship between the concentration of magnesium oxide (MgO) nanoparticles and its distinct biological activities towards mammalian cells and infectious bacteria for the first time. The effects of MgO nanoparticles on the viability of bone marrow derived mesenchymal stem cells (BMSCs) and infectious bacteria (both gram-negative Escherichia coli and gram-positive Staphylococcus epidermidis) showed a concentration-dependent behavior in vitro. The critical concentrations of MgO nanoparticles identified in this study provided valuable guidelines for biomaterial design toward potential clinical translation.

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Oxygen species adsorbed on ultraviolet-irradiated magnesium oxide

Cited by 46 publications

References 0 publications

Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

Evidence of Filamentary Switching in Oxide-based Memory Devices via Weak Programming and Retention Failure Analysis

Dissociation of magnesium oxide and magnesium hydroxide nanoparticles in physiologically relevant fluids

Concentration-dependent behaviors of bone marrow derived mesenchymal stem cells and infectious bacteria toward magnesium oxide nanoparticles

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