Bulletin of Faculty of Education, Nagasaki University : Natural Science

The permeation behavior of hydrogen through pure aluminum has been investigated in the temperature range of 625 K to 778 K by a gas permeation technique. The permeation rate of hydrogen was strongly affected by the conditions of the surface where the hydrogen was introduced into the sample. They varied characteristically by repeating the permeation run, which was bounded in the temperature range of 690K to 700K. At a higher temperature than 700K, the surface oxide layer was reduced by hydrogen during the permeation run, which resulted in the larger permeation rate of hydrogen in the subsequent permeation runs. At the sensitized surface by the reduction, the temporary poisoning took place and the permeation rate of hydrogen was decreased. The poisoned surface, however, was cleaned by keeping the sample under high vacuum at a higher temperature than 700K. The poisoning was closely related to the presence of carbon and its compounds on the top surface where the hydrogen was introduced into the sample

Recent progress of electrode architecture for MXene/MoS2 supercapacitor: preparation methods and characterizations

Since their discovery, MXenes have conferred various intriguing features because of their distinctive structures. Focus has been placed on using MXenes in electrochemical energy storage including a supercapacitor showing significant and promising development. However, like other 2D materials, MXene layers unavoidably experience stacking agglomeration because of its great van der Waals forces, which causes a significant loss of electrochemically active sites. With the help of MoS2, a better MXene-based electrodecan is planned to fabricate supercapacitors with the remarkable electrochemical performance. The synthesis of MXene/MoS2 and the ground effects of supercapacitors are currently being analysed by many researchers internationally. The performance of commercial supercapacitors might be improved via electrode architecture. This analysis will support the design of MXene and MoS2 hybrid electrodes for highly effective supercapacitors. Improved electrode capacitance, voltage window and energy density are discussed in this literature study. With a focus on the most recent electrochemical performance of both MXene and MoS2-based electrodes and devices, this review summarises recent developments in materials synthesis and its characterisation. It also helps to identify the difficulties and fresh possibilities MXenes MoS2 and its hybrid heterostructure in this developing field of energy storage. Future choices for constructing supercapacitors will benefit from this review. This review examines the newest developments in MXene/MoS2 supercapacitors, primarily focusing on compiling literature from 2017 through 2022. This review also presents an overview of the design (structures), recent developments, and challenges of the emerging electrode materials, with thoughts on how well such materials function electrochemically in supercapacitors

Ionic conductivity of polyvinyl alcohol-based gel electrolyte containing diethyl carbonate plasticizer for supercapacitor application

In this study, diethyl carbonate (DEC) as a plasticizer have been added to the gel electrolytes (GEs) system to influence the conductivity and storage performance of supercapacitor. The GE was prepared through a stirring method consisting of ethylene carbonate (EC), propylene carbonate (PC), potassium iodide (KI), polyvinyl alcohol (PVA) and dimethyl sulfoxide (DMSO). Consecutively, 5 wt. % DEC as a plasticizer was added for all samples. The GE preparation started with stirring all materials and heated until a homogenous gel was formed. The prepared GEs have been characterized with electrochemical impedance spectroscopy (EIS), which utilized to study the ionic conductivity of them. Sample with 15 wt. % of DEC in GE has the ionic conductivity of ~6 x 10-3 Scm-1. This study shows that by adding DEC will cause the ionic conductivity improved which is suggested that this DEC enhanced the ion’s mobility in the GEs’ structures. In cyclic voltammetry, the gel electrolyte with 15 wt.% DEC attain the highest specific capacitance of 55.56 Fg-1 (scan rate of 10 mV s-1). The charge-discharge curve of gel electrolyte acquires a shark fin-like shape which is alike with an ideal supercapacitor symmetric triangle shape. To summarize, the development of high conductivity GE may provide the path for high-performance supercapacitor

A comprehensive review of filler, plasticizer, and ionic liquid as an additive in GPE for DSSCs

Low ionic conductivity in gel polymer electrolytes (GPEs) affects low dye-sensitized solar cells (DSSCs) performance is a crucial issue. Generally, the GPEs contain polymer (act as solvent holder), solvent, and salt (as ions provider). Usually, the GPE-based DSSCs are assembly with three necessary compartments: working electrode, GPE, and platinum electrode. The DSSCs parameters are included open-circuit voltage, Voc; short-circuit current density, Jsc; fill factor, ff and efficiency, %. This review's main objective was to explore an additive such as plasticizer, filler, and ionic liquid effects on the ionic conductivity in GPEs by improving ions mobility and expanding the free volume of the GPE. The impact of additives in the GPE is also expected to enhance the DSSCs performance by increasing the Jsc, Voc, ff, and efficiency. This comprehensive review discussed the latest progress of GPE utilizing the additive by listing the literature from the recent ten years

Characterization of reduced graphene oxide/activated carbon-based electrode containing mixing CMC-SBR binder and application in supercapacitor

In this work, variation of mixing a combination of carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) as both used as the binder in the electrode has been studied. The purpose of using CMC-SBR as the binder in the electrode is to achieve a high supercapacitor performance. The electrode preparation has been carried out by mixing the reduced graphene oxide (rGO) and activated carbon (AC) in a blender. The binder preparation started by dissolving the CMC and SBR in the deionized water using a clean glass container. Then, rGO/AC has been stirred with the CMC-SBR for 60 minutes until a homogenous slurry formed. All electrodes have been characterized with Raman spectroscopy. The electrochemical tests such as cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) for all electrode compositions were performed. The electrode with 4:6 (in weight percentage) of CMC-SBR shows the highest specific capacitance (Csp) of 59.65 F g-1 (CV scan rate of 1 mV s-1) and 12.82 F g-1 from GCD test. This confirmed that the electrode containing 4 wt.% of CMC and 6 wt.% of SBR resulting in the best composition, which is reliable and practical for the supercapacitor application

A comprehensive review of filler, plasticizer, and ionic liquid as an additive in GPE for DSSCs

Low ionic conductivity in gel polymer electrolytes (GPEs) affects low dye-sensitized solar cells (DSSCs) performance is a crucial issue. Generally, the GPEs contain polymer (act as solvent holder), solvent, and salt (as ions provider). Usually, the GPE-based DSSCs are assembly with three necessary compartments: working electrode, GPE, and platinum electrode. The DSSCs parameters are included open-circuit voltage, Voc; short-circuit current density, Jsc; fill factor, ff and efficiency, %. This review’s main objective was to explore an additive such as plasticizer, filler, and ionic liquid effects on the ionic conductivity in GPEs by improving ions mobility and expanding the free volume of the GPE. The impact of additives in the GPE is also expected to enhance the DSSCs performance by increasing the Jsc, Voc, ff, and efficiency. This comprehensive review discussed the latest progress of GPE utilizing the additive by listing the literature from the recent ten years

Role of STAT4 polymorphisms in systemic lupus erythematosus in a Japanese population: a case-control association study of the STAT1-STAT4 region

IntroductionRecent studies identified STAT4 (signal transducers and activators of transcription-4) as a susceptibility gene for systemic lupus erythematosus (SLE). STAT1 is encoded adjacently to STAT4 on 2q32.2-q32.3, upregulated in peripheral blood mononuclear cells from SLE patients, and functionally relevant to SLE. This study was conducted to test whether STAT4 is associated with SLE in a Japanese population also, to identify the risk haplotype, and to examine the potential genetic contribution of STAT1. To accomplish these aims, we carried out a comprehensive association analysis of 52 tag single nucleotide polymorphisms (SNPs) encompassing the STAT1-STAT4 region.MethodsIn the first screening, 52 tag SNPs were selected based on HapMap Phase II JPT (Japanese in Tokyo, Japan) data, and case-control association analysis was carried out on 105 Japanese female patients with SLE and 102 female controls. For associated SNPs, additional cases and controls were genotyped and association was analyzed using 308 SLE patients and 306 controls. Estimation of haplotype frequencies and an association study using the permutation test were performed with Haploview version 4.0 software. Population attributable risk percentage was estimated to compare the epidemiological significance of the risk genotype among populations.ResultsIn the first screening, rs7574865, rs11889341, and rs10168266 in STAT4 were most significantly associated (P < 0.01). Significant association was not observed for STAT1. Subsequent association studies of the three SNPs using 308 SLE patients and 306 controls confirmed a strong association of the rs7574865T allele (SLE patients: 46.3%, controls: 33.5%, P = 4.9 × 10-6, odds ratio 1.71) as well as TTT haplotype (rs10168266/rs11889341/rs7574865) (P = 1.5 × 10-6). The association was stronger in subgroups of SLE with nephritis and anti-double-stranded DNA antibodies. Population attributable risk percentage was estimated to be higher in the Japanese population (40.2%) than in Americans of European descent (19.5%).ConclusionsThe same STAT4 risk allele is associated with SLE in Caucasian and Japanese populations. Evidence for a role of STAT1 in genetic susceptibility to SLE was not detected. The contribution of STAT4 for the genetic background of SLE may be greater in the Japanese population than in Americans of European descent