Specific heat study of Ga1-xMnxAs

Specific heat measurements were used to study the magnetic phase transition in Ga1-xMnxAs. Two different types of Ga1-xMnxAs samples have been investigated. The sample with a Mn concentration of 1.6% shows insulating behavior, and the sample with a Mn concentration of 2.6% is metallic. The temperature dependence of the specific heat for both samples reveals a pronounced lambda-shaped peak near the Curie temperature, which indicates a second-order phase transition in these samples. The critical behavior of the specific heat for Ga1-xMnxAs samples is consistent with the mean-field behavior with Gaussian fluctuations of the magnetization in the close vicinity of TC.Comment: 12 pages, 5 figure

Sustainable E-Governance: The Relationship among Trust, Digital Divide, and E-Government

This study empirically examines the correlation between the quality of e-government and trust in government. It used survey data collected in 2013 from the metropolitan areas of Seoul. An index was developed to measure the quality of e-government services, and the Gov 3.0 values were reflected in the analysis, including openness, sharing, communication, and collaboration. The results show a partial correlation between the quality of e-government service and trust in government. In addition, the level of trust varied according to the different type of the digital divide groups. It suggests that as ICT (Information Communication Technology) has become more sophisticated, a willingness to share information among organizations and stakeholders may become a major factor to thoseactively seeking information and resources to make value-added products. It also suggests that more integrated data management including network securityand an open attitude toward information sharing will be more important beyond the level of technical issues

A Review of Various Attempts on Multi-Functional Encapsulation Technologies for the Reliability of OLEDs

As the demand for flexible organic light-emitting diodes (OLEDs) grows beyond that for rigid OLEDs, various elements of OLEDs, such as thin-film transistors, electrodes, thin-film encapsulations (TFEs), and touch screen panels, have been developed to overcome OLEDs’ physical and chemical limitations through material and structural design. In particular, TFEs, which protect OLEDs from the external environment, including reactive gases, heat, sunlight, dust, and particles, have technical difficulties to be solved. This review covers various encapsulation technologies that have been developed with the advent of atomic layer deposition (ALD) technology for highly reliable OLEDs, in which solutions to existing technical difficulties in flexible encapsulations are proposed. However, as the conventional encapsulation technologies did not show technological differentiation because researchers have focused only on improving their barrier performance by increasing their thickness and the number of pairs, OLEDs are inevitably vulnerable to environmental degradation induced by ultraviolet (UV) light, heat, and barrier film corrosion. Therefore, research on multi-functional encapsulation technology customized for display applications has been conducted. Many research groups have created functional TFEs by applying nanolaminates, optical Bragg mirrors, and interfacial engineering between layers. As transparent, wearable, and stretchable OLEDs will be actively commercialized beyond flexible OLEDs in the future, customized encapsulation considering the characteristics of the display will be a key technology that guarantees the reliability of the display and accelerates the realization of advanced displays

Nanoparticle-Based Electrodes with High Charge Transfer Efficiency through Ligand Exchange Layer-by-Layer Assembly

Organic-ligand-based solution processes of metal and transition metal oxide (TMO) nanoparticles (NPs) have been widely studied for the preparation of electrode materials with desired electrical and electrochemical properties for various energy devices. However, the ligands adsorbed on NPs have a significant effect on the intrinsic properties of materials, thus influencing the performance of bulk electrodes assembled by NPs for energy devices. To resolve these critical drawbacks, numerous approaches have focused on developing unique surface chemistry that can exchange bulky ligands with small ligands or remove bulky ligands from NPs after NP deposition. In particular, recent studies have reported that the ligand-exchange-induced layer-by-layer (LE-LbL) assembly of NPs enables controlled assembly of NPs with the desired interparticle distance, and interfaces, dramatically improving the electrical/electrochemical performance of electrodes. This emerging approach also demonstrates that efficient surface ligand engineering can exploit the unique electrochemical properties of individual NPs and maximize the electrochemical performance of the resultant NP-assembled electrodes through improved charge transfer efficiency. This report focuses on how LE-LbL assembly can be effectively applied to NP-based energy storage/conversion electrodes. First, the basic principles of the LE-LbL approach are introduced and then recent progress on NP-based energy electrodes prepared via the LE-LbL approach is reviewed. © 2020 Wiley-VCH GmbH1

Immunostaining Extracellular Vesicles Based on Aqueous Two-Phase System: for Analysis of Tetraspanins

Immunostaining of extracellular vesicles (EVs) has become necessary for the characterization of EV subtypes, clarification of the EV biogenesis/cellular uptake pathway, drug delivery, etc. Immunostained EVs must be in suspension for further downstream analyses or uses. However, conventional EV immunostaining methods yielding EVs in suspension lack either sufficient recovery or staining specificity because of the washing steps. In this study, we have devised and tested a method to wash immunostained EVs with successive aqueous two-phase system (ATPS) separations. The ATPS is a liquid–liquid extraction procedure that ensures a gentle separation of target molecules. The ATPS has been successfully employed to separate EVs from other impurities with high yield and high purity. Immunostained EVs were washed with the ATPS and compared with other immunostaining methods to confirm the proposed method’s high EV recovery and staining accuracy. According to the result, the ATPS-based EV immunostaining method required as low as ∼1 μg without compromise of accuracy and recovery.11Nscopu

Extracellular Vesicles Generated Using Bioreactors and their Therapeutic Effect on the Acute Kidney Injury Model

Extracellular vesicles (EVs) are nano-sized vesicles secreted by cells, having beneficial effects for various types of regenerative processes. Although EVs have shown promising effects as therapeutic agents, these effects are difficult to research due to the limitations of EV production. In this study, an EV production method based on a flat-plate bioreactor is introduced. The bioreactor produces approximately seven times more mesenchymal stem cell-derived EVs than static culture conditions. The mechanism underlying the increased production of EVs in a flat-plate bioreactor and its application to acute kidney injury is investigated. This study describes the mechanism of EV production by demonstrating the link between EV biogenesis and increased calcium ion concentration under flow conditions. EVs secreted by cells cultured in the bioreactor have therapeutic efficacy in terms of improving kidney damage, resulting in tissue regeneration in a cisplatin-induced acute kidney injury model. This method will help overcome the limitations of EV production, and the analysis of the application of EVs will increase their reliability as well as the understanding of the use of bioreactor-derived EVs as therapeutic agents.11Nsciescopu