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Al electroplating using ionic liquids (ILs) has been extensively studied for various potential applications, including corrosion-resistant coatings. When Al electroplating is to be performed commercially for many small objects, adopting the barrel plating method is reasonable for improving productivity and reducing manufacturing costs. However, little is known about the barrel-plating conditions for the formation of Al coatings. In this study, the barrel plating conditions for forming Al coatings on steel bolts using ILs composed of 1-ethyl-3-methylimidazolium chloride (EMIC) and aluminum chloride (AlCl3) were investigated. Hull cell tests showed that the IL with an AlCl3/EMIC molar ratio of 1.2 has a higher covering power than the IL with a higher AlCl3 ratio. Barrel plating using the IL with an AlCl3 ratio of 1.2 enabled complete coverage of the bolt with the Al coating. The uniformity of the Al coating on the bolts was further improved by adjusting the rotation speed of the barrel. Furthermore, a simple pretreatment procedure for steel bolts was proposed to obtain an electrodeposited Al coat that adheres well to steel bolts.

The sensitivity of X-ray detectors can be effectively improved by forming a columnar grain structure in the photoconductive layer, given that few grain boundaries exist across the direction of electron–hole pair collection. Herein, we demonstrate the fabrication of Cs₂AgBiBr₆ films with columnar grain structures using the mist deposition method. An X-ray detector based on a 92 μm-thick Cs₂AgBiBr₆ film with columnar grains exhibits a high sensitivity of 487 μC Gyair⁻¹ cm⁻², which is the highest among detectors based on Cs₂AgBiBr₆ polycrystalline thick films. To reveal the mechanism of columnar grain growth, we investigate the effects of deposition conditions, including the precursor solution concentration and substrate temperature. From the results, we conclude that the re-dissolution capability of the precursor solution is a key factor promoting the grain growth on the film surface, leading to columnar growth. Furthermore, we realize the columnar grain growth of a CH3NH3PbBr3 film to demonstrate the generality of the mist deposition method.

The electrodeposition of tungsten at moderate temperatures (4 and WCl5 in 1-ethyl-3-methylimidazolium chloride (EMIC) and EMIC–AlCl3 ionic liquids at 80 °C–120 °C. W-rich films with a thickness of approximately 1 μm were obtained from the Lewis acidic EMIC–AlCl3–WCl5 bath, whereas the other baths did not yield any deposits. The films obtained from the EMIC–AlCl3–WCl5 bath at 80 °C had higher W contents of 54 at.% than those obtained at 120 °C. X-ray absorption near-edge structure spectra of the W-rich films indicated that W existed in an oxidized state. The findings of this study can be used as a guide to explore optimal electrolytes and electrolytic conditions for the electrodeposition of metallic W at moderate temperatures.

Several studies have shown that Cl− channels regulate the differentiation of some cell types. Thus, we investigated the role of Cl− channels on adipocyte differentiation using adipose tissue-derived stem cells (ASCs) and Cl− channel blocker. We induced rabbit ASCs into adipocytes using Cl− channel blocker. The expression levels of adipocyte markers were no significant difference between the cells treated with a Cl− channel blocker NPPB and untreated cells. However, when the cells were treated with NPPB, lipid droplets (LDs) sizes decreased compared with the untreated control. Interestingly, the expression levels of Rab8a, which is known as a regulator of LD fusion, were also decreased in the cells treated with NPPB. Other Cl− channel blockers, DIDS and IAA-94, also inhibited large LDs formation and Rab8a expression. These results demonstrate that Cl− channels do not regulate the adipocyte differentiation, but do regulate the LDs formation via Rab8a expression. Abbreviations: ASCs: adipose tissue-derived stem cells; LDs: lipid droplets; RUNX2: runt-related transcription factor 2; CFTR: cystic fibrosis transmembrane conductance regulator; TG: triacylglycerol; FA: fatty acid; GLUT4: glucose transporter type 4; ER: endoplasmic reticulum; ADRP: adipose differentiation-related protein; TIP47: tail-interacting protein of 47 kD; HSL: hormone sensitive lipase; PBS: phosphate-buffered saline; DMEM: Dulbecco’s modified Eagle Medium; FBS: fetal bovine serum; SMA: smooth muscle actin; FAS: fatty acid synthase; ZONAB: ZO-1 associated nucleic acid binding protein; PPAR-γ: peroxisome proliferator-activated receptor-γ; C/EBPα: CCAAT/enhancer binding protein α; CE: cholesteryl ester; V-ATPase: vacuolar H+ ATPase.

X-ray imaging is a valuable technique used for medical imaging and non-destructive inspection of industrial products. However, the radiation may put humans at risk of developing cancer. Consequently, highly sensitive X-ray detectors, which enable X-ray imaging at a low dose rate, are required. Metal halide perovskite materials have demonstrated excellent X-ray detection performance including a high sensitivity owing to their high absorption coefficient, high carrier mobility, and long carrier lifetime. However, perovskite thick films with a large area, which is essential to realize the application of such materials to X-ray imaging devices have not been extensively investigated. To this end, in this study, a polymer is employed as a buffer layer to avoid film exfoliation, which makes it difficult to fabricate perovskite thick films, and a 110-μm-thick CsPbBr3 film is successfully obtained using a scalable solution method. In addition, an X-ray detector based on the CsPbBr3 thick film is fabricated, which demonstrates a sensitivity of 11,840 μC Gyair-1 cm-2. This sensitivity is approximately 600 times higher than that of the existing commercial a-Se X-ray detectors.

Wide-bandgap oxide semiconductors have received significant attention as they can produce devices with high output and breakdown voltage. p-Type conductivity control is essential to realize bipolar devices. Therefore, as a rare wide-bandgap p-type oxide semiconductor, NiO (3.7 eV) has garnered considerable attention. In view of the heterojunction device with Ga2O3 (4.5–5.0 eV), a p-type material with a large bandgap is desired. Herein, we report the growth of a Ni1-xMgxO thin film, which has a larger bandgap than NiO, on α-Al2O3 (0001) substrates that was developed using the mist chemical vapor deposition method. The Ni1-xMgxO thin films epitaxially grown on α-Al2O3 substrates showed crystallographic orientation relationships identical to those of NiO thin films. The Mg composition of Ni1-xMgxO was easily controlled by the Mg concentration of the precursor solution. The Ni1-xMgxO thin film with a higher Mg composition had a larger bandgap, and the bandgap reached 3.9 eV with a Ni1-xMgxO thin film with x = 0.28. In contrast to an undoped Ni1-xMgxO thin film showing insulating properties, the Li-doped Ni1-xMgxO thin film had resistivities of 101–105 Ω·cm depending on the Li precursor concentration, suggesting that Li effectively acts as an acceptor.

Rat hepatitis E virus (HEV-C1) in the Orthohepevirus C species has been reported to cause zoonotic infection and hepatitis in humans. HEV-C1 strains have been detected from wild rats in many countries in Europe, Asia, and North America. However, in Japan, no HEV-C1 strains have been identified. In the present study, 5 (1.2%) of 428 wild rats (Rattus norvegicus or R. rattus) were positive for anti-HEV-C1 IgG. Although all 428 rat sera were negative for HEV-C1 RNA, it was detectable in 20 (19.8%) of 101 rat fecal samples collected on a swine farm, where HEV (genotype 3b, HEV-3b) was prevalent and wild rats were present. In addition, HEV-C1 RNA was detectable in the intestinal contents and liver tissues of 7 (18.9%) of 37 additional rats captured on the same farm. The HEV-C1 strain (ratEJM1703495L) obtained in this study shared only 75.8-84.7% identity with reported HEV-C1 strains over the entire genome but propagated efficiently in cultured cells. HEV-3b strains were detected in the rats' intestinal contents, with 97.3-99.5% identity to those in pigs on the same farm, but were undetectable in rat liver tissues, suggesting that wild rats do not support the replication of HEV-3b of swine origin.

Mist chemical vapor deposition (mist CVD), which is capable of producing oxide films over large areas at a high productivity and low cost, has been proposed as a fabrication method for VO2 thin films for smart windows. However, the thermochromic properties of the VO2 films previously prepared by mist CVD are not sufficient for application in smart windows. In this study, to obtain a high-quality VO2 film, we investigated the effects of the solvent of the precursor solution on the resulting film in mist CVD. Films consisting of a single phase of VO2 were obtained when a water-based precursor solution was used. In contrast, V2O3 films are formed when a methanol-based precursor solution is used. The VO2 film deposited from water solution exhibited high visible transmittance along with a large change in the infrared transmittance with temperature change. The high quality of the VO2 film indicates that mist CVD is an effective method for the fabrication of VO2-based smart windows.

In this study, we explored the feasibility of WO3 surface layer formation on electrodeposited Al–W alloy coatings by selective dissolution and heat treatment, with the aim of providing corrosion-resistant Al–W alloy coatings with photocatalytic self-cleaning properties under visible light illumination. The selective dissolution of Al and oxidation of residual W was carried out by immersing Al–W alloy films in an aqueous solution of nitric acid. A nanostructured H2WO4·H2O surface layer was formed on the alloy film by this process. The H2WO4·H2O layer was dehydrated to WO3 by heat treatment, yielding a multilayered WO3/Al–W alloy film with an approximately 300 nm thick WO3 layer. The WO3/Al–W alloy film exhibited photocatalytic self-cleaning, as demonstrated by the photodegradation of stearic acid and methylene blue. We also confirmed that selective dissolution and heat treatment did not significantly diminish the corrosion resistance of the Al–W alloy films.

Geranylgeranylacetone (GGA) has been used as an antiulcer drug and also is known as inducer of heat shock protein 70 that has cytoprotective effects especially in hyperglycemic condition. In contrast, cytotoxicity of GGA has also been reported. Some studies have reported that GGA suppresses cell growth and induces apoptosis in cell models of human leukemia, ovarian carcinoma, and colon cancer in vitro. Therefore, the aim of this study was to determine whether GGA can have a cytotoxic effect on a human cervical cancer cell line (HeLa), human colorectal adenocarcinoma cells (Caco-2), and human embryonic kidney cells 293 (HEK) in normal-glucose and high-glucose environments (NG and HG, respectively). The results showed that 100 μM GGA inhibited proliferation of HeLa cells only in NG environment despite inhibiting proliferation of Caco-2 and HEK cells regardless of glucose concentration. Cell viability assay revealed that GGA decreased viability of HeLa, Caco-2, and HEK cells only in NG environment. Flow cytometric analyses revealed that the type of cell death was a combination of necrosis and apoptosis. Our study revealed that difference in cytotoxicity of GGA is influenced by glucose condition. The cytotoxic effects of GGA are attenuated in the HG condition. Since both cytotoxic and cytoprotective effects are reported about GGA, further research is needed about the mechanism of the cytotoxic effects.

Functional central airway epithelial cells (CAECs) from induced pluripotent stem cells (iPSCs) are an attractive potential cell source for central airway regeneration. The central airway epithelium, such as the tracheal epithelium, is composed of ciliated cells, goblet cells, and basal cells and has physiologically important functions such as the regulation of water volume on the airway surface by Cl- and water channels and the elimination of particles inhaled from the external environment by ciliary movement. Previous work from our group and from other research groups has reported the generation of airway epithelial cells from iPSCs. However, it remains unclear whether iPSC-derived CAECs express the various channels that are required for the regulation of water volume on the airway surface and whether these channels function properly. In this study, we generated CAECs from iPSCs supplemented with activin and bFGF using air-liquid interface culture. We then evaluated the physiological functioning of the iPSC-derived CAECs by examining the gene expression and transport functions of Cl - channels using a halide ion-sensitive yellow fluorescent protein and ciliary movement. Reverse-transcription polymerase chain reaction and immunohistochemistry indicated that various channel markers such as cystic fibrosis transmembrane conductance regulator (CFTR) and aquaporin (AQP) were present in iPSC-derived CAECs. Furthermore, the transport functions of Cl - channels and CFTR were successfully confirmed. Finally, ciliary movement was measured, and a ciliary beating frequency (CBF) of approximately 10 Hz was observed. These results demonstrate that CAECs generated by our method have physiological functions similar to those of native CAECs.

Undoped and Li-doped NiO thin films were grown on α-Al2O3 (0 0 0 1) substrates by mist chemical vapor deposition. Both undoped and Li-doped NiO thin films grew bi-epitaxially on the substrates with crystallographic orientation relationships of NiO(1 1 1)[ 1 ¯ 1 0] || α-Al2O3(0 0 0 1)[0 1 1 ¯ 0] and NiO(1 1 1)[1 1 ¯ 0] || α-Al2O3(0 0 0 1)[0 1 1 ¯ 0]. In the Li-doped NiO thin film, a periodic structure was observed, in accordance with a mirror-symmetrical oxygen layer on the terraces of the substrate. Both undoped and Li-doped NiO thin films exhibited high transmittance (>80%) in the visible-light region and optical bandgaps of 3.7–3.8 eV. The undoped NiO thin film showed insulating properties and a resistivity of 106 Ω cm or higher. In contrast, the Li-doped NiO thin films had resistivities of 101–105 Ω cm, depending on the Li precursor concentration. Furthermore, they exhibited positive Seebeck coefficients, indicating their p-type conductivity. These results indicate that Li dopants effectively act as acceptors in NiO thin films.

A composition-modulated Co–Ni laminated plating has been developed to prolong the lifetime of molds to be employed in continuous steel casting. We have investigated the relationship between the laminated structure and the mechanical properties of the plating films. The tensile strength of as-plated film was enhanced by the thinned thickness of the constituent layers, while the elongation received no effect of the thickness change of the constituent layer and remained almost stable in the range from 3 to 5%. Heat treatment at 400°C have brought about the improvement both in the tensile strength and the elongation. The improvement in the elongation was as remarkable as reached 13% in the film composed of layers with a thickness of 0.8 µm. The layer with low Ni content had an hcp structure, and that with high Ni content produced two phases of the hcp and fcc structures in the as-plated state. By the heat treatment, the high Ni-content layer turned into the single fcc phase, while the low Ni-content layer kept the hcp phase, and accordingly, the film structure changed into the one where the lamination of the hcp and fcc layers was distinct. The fact that the fcc layers, which was easily deformed, were formed continuously in the lateral direction, was seemed to contribute to the significant improvement in the elongation after heat treatment.

Aluminum electrodeposition using ionic liquids or deep eutectic solvents has attracted significant interest for coating applications. Although Al electrodeposition is usually carried out in a nitrogen- or argon-filled glove box, there may be a potential for process cost reduction if the Al electrodeposition process could be carried out in a dry atmosphere. In this study, we examined two commonly used baths, namely a 1-ethyl-3-methylimidazolium chloride (EMImCl)–AlCl3 ionic liquid and an acetamide (AcAm)–AlCl3 deep eutectic solvent, to determine their respective feasibilities for the electrodeposition of a uniform Al film in dry air. Electrodeposition in dry air using the AcAm–AlCl3 bath produced uniform Al films even after the bath had been used for more than 10 weeks, whereas electrodeposition in dry air using the EMImCl–AlCl3 bath failed to produce an Al film covering the entire substrate. The current efficiency was almost 100% in the AcAm–AlCl3 bath, whereas the value decreased to 50% in EMImCl–AlCl3 bath in dry air. The findings of this study therefore reveal that AcAm–AlCl3 is a suitable bath for Al electrodeposition in dry air.

Deposition methods using aqueous solutions have been developed as cost-effective routes to form transparent ZnO semiconductor films. Chemical bath deposition (CBD) employing a solution of zinc nitrate and hexamethylenetetramine is one of the most popular methods to grow ZnO using aqueous solutions. However, the electrical properties of ZnO films grown by CBD have not been extensively studied. In this study, epitaxial ZnO films were prepared by CBD using a flow reactor under various deposition conditions, and the temperature and reactant concentrations required for the growth of a transparent ZnO film with a smooth surface were determined. The electrical properties of the transparent ZnO films were examined by resistivity and Hall effect measurements. The optimum flow rate of the reaction solution, leading to the fastest growth of ZnO, was also identified. The ZnO film grown at such flow rate exhibited the highest electrical mobility. The carrier concentration and mobility of the ZnO film grown under the optimized conditions were 1.2 × 10¹8 cm⁻³ and 21 cm² V⁻¹ s⁻¹, respectively.

With the aim of extending the lifetime of molds used for continuous steel casting, we developed a composition-modulated Co-Ni alloy plating with alternately laminated layers of different compositions. Alloy films with laminated structures comprising few-micrometer-thick layers were formed using a single plating bath by periodically altering the agitation intensity in the bath during plating. The hardness of the as-plated composition-modulated Co-Ni alloy film was 350 HV, which was higher than that of a conventional non-laminated Co-Ni alloy plating film. Heat treatment slightly decreased the hardness. Nevertheless, the composition-modulated film exhibited higher tensile strength and higher hardness than the conventional alloy film after heat treatment at temperatures of 200-700 ℃. The breaking elongation of the composition-modulated film increased to 30% after heat treatment at 700 ℃. Finally, the composition-modulated Co-Ni alloy plating was applied to a mold surface, which was then used for continuous steel casting. It exhibited excellent resistance against crack formation by thermal shock resulting from contact with molten steel during continuous casting.

Single crystal semiconductors almost always exhibit better optoelectrical properties than their polycrystalline or amorphous counterparts. While three-dimensionally (3D) nanostructured semiconductor devices have been proposed for numerous applications, in the vast majority of reports, the semiconductor is polycrystalline or amorphous, greatly reducing the potential for advanced properties. While technologies for 3D structuring of semiconductors via use of a 3D template have advanced significantly, approaches for epitaxially growing nanostructured single crystal semiconductors within a template remain limited. Here, we demonstrate the epitaxial growth of 3D-structured ZnO through colloidal templates formed from 225 and 600 nm diameter colloidal particles via a low-temperature (∼80 °C) hydrothermal process using a flow reactor. The effects of the pH of the reaction solution as well as the additive used on the 3D epitaxy process are investigated. The optical and electrical properties of the epitaxially grown...

Hepatitis E virus (HEV) causes acute or chronic hepatitis in humans and can be transmitted via the fecal-oral route. Pigs are one of the main reservoirs for this infection. Sixty pigs, 4-5 months of age, on a swine herd in Japan had detectable anti-HEV IgG antibodies, and five (8.3%) of them had ongoing infection of genotype 3 HEV. Five HEV strains obtained from the viremic pigs shared 98.8-100% nucleotide identity, and one representative strain (swHE1606845), whose entire genomic sequence was determined in this study, differed by 14.1-19.6% from the reported HEV strains of subtypes 3a-3k and by 14.7-19.1% from other genotype 3 HEV strains whose subtypes have not yet been assigned. swHE1606845 showed a higher nucleotide p-distance value of ≥0.143 with the genotype 3 HEV strains of subtypes 3a-3k and ≥0.152 with other genotype 3 strains of unassigned subtypes. A SimPlot analysis revealed a lack of recombination events. These results indicate that swHE1606845 is a candidate member of a novel subtype of genotype 3. Further efforts to identify the swHE1606845-like novel strain are warranted to clarify the origin of this strain and to determine the complete nucleotide sequences of two additional swHE1606845-like strains for assigning a new subtype.

Various annealing conditions were examined for enhancing the electrical conductivity of gallium-doped ZnO (ZnO:Ga) epitaxial films grown from a low-temperature aqueous solution. The resistivity of the films decreased with increasing annealing temperature, accompanying increases in both the carrier concentration and mobility. However, the improvement obtained from 0.5 h of annealing was limited because the films spalled when the temperature exceeded ∼300 °C. The temperature at which spalling of the films occurred depended on the annealing atmosphere, and it was lower in 5%H 2 –Ar than in air or vacuum. Thermal desorption spectroscopy showed that the cause of spalling was expulsion of H 2 O vapor from the interior of the film, indicating that water molecules or hydroxides were incorporated into the crystal during film growth. Analysis of the variations in electrical properties with increasing annealing duration revealed that the electrical properties were quickly improved upon heating before the film spalled. Thus, by limiting the annealing duration to ≤20 s, annealing could be performed at a temperature as high as 580 °C without spalling of the film, which yielded the lowest resistivity of 4.7 × 10 −4 Ω cm. The annealed film exhibited transmittance as high as >75% in the visible spectrum.

In this study, we investigated the feasibility of a new process for the fabrication of Al-based composite coatings containing TiO₂ particles with high photocatalytic activity. In the first step of this process, Al-TiO₂ composite coatings were electrodeposited in a dimethyl sulfone-aluminum chloride bath with suspended TiO₂ particles yielding Al-matrix composite coatings with uniformly dispersed TiO₂ particles. Subsequently, the electrodeposited Al-TiO₂ composite coatings were anodized in oxalic aqueous solution. Through this anodization step, the Al matrix was converted into an alumina layer with many nanopores extending from the surface of the coating toward the substrate. As a consequence, a porous alumina layer supporting TiO₂ particles was formed. The photocatalytic activity of the anodized composite coatings was confirmed to be higher than that of the as-deposited coatings.

Sunscreens today contain several synthetic UV (Ultraviolet) filter molecules to protect the skin epidermis from UV radiation damage. However, these molecules may create several negative effects on human skin. Due to this condition, there is an increase in the development of natural products to replace uses of these synthetic chemicals. Brown macroalgae Sargassum has been recently studied for its photoprotective activities. The purpose of this study is to investigate photoprotective activity of one of most abundant Sargassum species in Lombok coast, Sargassum cristaefolium. Spectrophotometry analysis with UV-VIS revealed the UV spectra absorbing capability of Sargassum cristaefolium (SC) in the UVA spectrum range (314&ndash, 400 nm). Furthermore, spectrometry analyses with LC-MS revealed the existence of UV absorbing compound MAA-palythene. In correlation, SC ethanol extracts also demonstrate that it could protect DNA from UVA irradiation as analyzed in vitro in HeLa cell model. The effects of SC on UVA exposed-dorsal mice skin have also shown interesting results, as mice pretreated with SC before UVA exposure showed protective activity on the epidermal integrity similar as positive control. Whereas, UV exposed mice without SC or commercial products resulted in increased epidermal thickness, which is the common parameter of skin photoaging. In addition, pretreated mice with SC also show protective effects in the formation of collagen connective tissues. Overall, current results show promising photoprotective activity of SC against UV radiation. More advanced investigations of SC as a potential photoprotective agent would be reasonable for development of macroalgae-based natural skin protection products.

The electrodeposition of iron alloys is a significant research topic, owing to the potential applications such as corrosion/wear-resistant coatings1, magnetic thin films2, and catalyst electrodes3. Although aqueous electrolytes have been mostly used for electrodeposition, vigorous hydrogen evolution on the cathode can lead to hydrogen embrittlement and precipitation of metal hydroxides2. In addition, less noble elements such as aluminum and silicon cannot be co-deposited from aqueous electrolytes due to the limited electrochemical window. To overcome the limitations of aqueous solutions, non-aqueous systems such as molten salts and ionic liquids have gained significant research attention. The electrochemical behaviour of iron complexes in imidazolium- and pyrrolidinium-based ionic liquids, and electrodeposition of metallic Fe was demonstrated in some liquids4,5. Many ionic liquids are, however, not viable on a practical scale. In this study, we explored an alternative electrolyte to ionic liquids for electrodeposition of iron. A mixture of ferric chloride and acetamide is shown to give a liquid at ambient temperature. This eutectic mixture has a higher conductivity than comparable eutectics formed from either aluminium or zinc chloride. Ferric chloride disproportionates to form both anionic and cationic iron species identified using spectroscopic methods. The electrodeposition of dense metallic iron film was demonstrated. References N. Tsyntsaru et al., Surf. Eng. Appl. Electrochem., 48, 491–520 (2013) G. Panzeri et al., Electrochim. Acta, 271, 576–581 (2018) N.-C. Lo et al., J. Electrochem. Soc., 163, D9–D16 (2016). P. Giridhar, B. Weidenfeller, S. Z. El Abedin, and F. Endres, ChemPhysChem, 15, 3515–3522 (2014). Y. Zhu, Y. Katayama, and T. Miura, J. Electrochem. Soc., 159, D699–D704 (2012).

The electrodeposition of Al has been studied in various ionic liquids represented by the 1-ethyl-3-methylimidazolium chloride-AlCl3 system. However, AlCl3-based (chloroaluminate) ionic liquids are generally handled in an inert atmosphere of nitrogen or argon because they are highly hygroscopic and susceptible to hydrolysis through the reaction with moisture in the air. To maintain an inert atmosphere, a closed system that typically uses a glove box is required, but operation in a closed system leads to low productivity and high cost. Therefore, electrodeposition in an inert atmosphere is unsuitable for mass production on an industrial scale. To alleviate this problem, we have previously studied the feasibility of Al electrodeposition in dry air using chloroaluminate ionic liquids. Because the electrodeposition process in dry air does not require a glove box, it is considered to be more productive than the electrodeposition process under an inert atmosphere. In our previous study, four different chloroaluminate ionic liquids consisting of different organic cations ([cation]Cl-AlCl3) with a molar ratio of [cation]Cl : AlCl3 = 1 : 2 were used as Al electrodeposition baths to study Al electrodeposition behavior in dry air. The cations used were 1-ethyl-3-methylimidazolium (EMI+), 1-butylpyridinium (BP+), 1-butyl-1-methylpyrrolidinium (BMP+), and trimethylphenylammonium (TMPA+). We found that electrodeposition in dry air using the bath composed of EMI+ or BP+ could not produce an Al film covering the entire surface of the substrate, whereas electrodeposition using the bath composed of BMP+ or TMPA+ could produce an Al film covering the entire surface of the substrate in dry air as well as in an inert atmosphere. The reason for the difference in the results of Al electrodeposition in dry air according to cationic species has not yet been ascertained, but it is speculated that dissolved oxygen has some influence on the Al electrodeposition. In the present study, we measured the concentration of oxygen dissolved in four types of ionic liquids in dry air. For measuring the dissolved oxygen concentration, ionic liquids with a composition of [cation] Cl: AlCl3 = 1: 0.9 were used. This composition was chosen because only AlCl4 −, which is an ionic species that is difficult to be reduced to Al metal, is present in the bath when the AlCl3 mole fraction is less than 50 mol% (Lewis base)in chloroaluminate ionic liquids. Consequently, Al electrodeposition does not occur, and low extent of electrochemical reaction other than Al electrodeposition at a potential of 0 V vs. Al / Al (III) or less can be investigated. The concentration of dissolved oxygen was measured by chronoamperometry using two types of electrodes, a macroelectrode and a microelectrode, both of which have a circular active area with a diameter in the order of millimeter and micrometer, respectively. In the case of chronoamperometric measurement with a macroelectrode, the reduction current of oxygen follows the equation in the upper row in Table 1, assuming that the reaction rate is controlled by the planar diffusion of oxygen from the bulk electrolyte to the surface of the electrode. Upon measuring the current–time response, two unknowns remain, namely, the concentration and the diffusion coefficient of dissolved oxygen; and it is not possible to determine the dissolved oxygen concentration through the chronoamperometric measurement using the macroelectrode alone. In the case of chronoamperometric measurement with a microelectrode, the geometry of the diffusion of the reactant to the electrode surface changes to semi-spherical, and the reduction current of oxygen thus follows the equation in the lower row in Table 1. The concentration and diffusion coefficient of dissolved oxygen can thus be determined through the two chronoamperometric measurements. The chronoamperometric measurements revealed that there was no significant difference in the oxygen concentrations of the ionic liquids with different cationic species. The results that we have obtained so far are as follows: 1) In an inert atmosphere, an Al film covering the entire surface of the substrate can be electrodeposited from a bath containing any cation species. 2) In dry air, an Al film covering the entire surface of the substrate can only be electrodeposited from some baths composed of specific cation species. 3) There is no significant difference in the dissolved oxygen concentrations of the baths in dry air, even though the cation species in the baths are different. In consideration of these results, the reason for the different results of Al electrodeposition in dry air according to the cationic species is neither dissolved oxygen alone nor cationic species alone but the combined action of both dissolved oxygen and the cation. Figure 1

Molybdenum dioxide (MoO2), which exhibits both high chemical stability and high electrical conductivity, has been studied for various applications, e.g. as a photocatalyst, an active material for secondary batteries, and the capacitor electrode of dynamic random access memory devices. MoO2 films are mainly fabricated by vacuum processes, which incur a high manufacturing cost. In this study, we fabricated MoO2 thin films by mist chemical vapor deposition. Since this method does not require vacuum or a volatile precursor, the processing cost is reduced. Examination of the films deposited at various positions in the furnace at different furnace temperatures revealed that smooth MoO2 films composed of densely packed crystal grains with a constant thickness of 200 nm can be obtained over a wide area of >30 cm2 at a furnace temperature of ~480 °C. The films showed low electrical resistivity of 2 × 10−3 Ω cm. Thus, this study provides a low-cost method for the fabrication of MoO2 thin films.

The electrodeposition of iron and iron-based alloys is important for a variety of coating technologies. This study demonstrates that eutectics of ferric chloride and acetamide are easily formed and a 1:4 M mixture gives a liquid at ambient temperature. This eutectic mixture has a higher conductivity resulting from a lower viscosity than comparable eutectics formed from either aluminium or zinc chloride. Ferric chloride disproportionates to form both anionic and cationic iron containing species and these were identified using a variety of spectroscopic methods. The electrodeposition of iron and iron-nickel alloys was demonstrated and it was shown that the iron-nickel alloys demonstrated improved anti-corrosion properties.

Tungsten carbide thin films are used as wear-resistant coatings. For such applications, it is industrially advantageous to form high-quality thin films on substrates with large areas or complex shapes under atmospheric pressure. Herein, we investigated the feasibility of forming tungsten carbide thin films using a mist chemical vapor deposition method. WC1-x thin films with smooth surfaces were obtained at growth temperatures of 650 °C or above, and the elemental composition ratios of C/W and N/W gradually approached 1 and 0, respectively, with increasing growth temperature. The hardness and Young’s modulus of the film obtained at 750 °C were 25 GPa and 409 GPa, respectively. The grown WC1-x films have potential for use as hard coatings.

Electroplating of Al on a Mg alloy using a dimethyl sulfone–aluminum chloride bath was studied. Although dense and uniform Al films were electrodeposited on the Mg alloy from the bath at 110 °C, the adhesion of the Al film was poor when the electrodeposition was carried out directly onto the bare alloy. Subjecting the Mg alloy to zincate pretreatment resulted in Al films with good adhesion. The adhesion strength of the Al films was measured using a pull-off test. The fractured interface was observed with SEM–EDX, which revealed that the Mg alloy substrate reacted with the bath before the electrodeposition of Al started. The reaction products formed on the substrate were detrimental to the adhesion of the electrodeposited Al film. Polarization curves measured for the Al-coated Mg alloy in a 3.5 wt.% NaCl solution at room temperature (25 °C) showed that the Al film electrodeposited from the DMSO2–AlCl3 bath can effectively prevent the Mg alloy from rapid corrosion.

An aqueous process based on a unique flow-reactor design was developed for the preparation of gallium-doped ZnO (ZnO:Ga) epitaxial films with a low electrical resistivity. In this process, a ZnO:Ga film was grown on a ZnO-seeded sapphire substrate heated at 80°C under a constant flow of a reaction solution. The Ga content of the resulting films was found to increase in relation to the concentration of GaCl[3] used–0 to 9 mM GaCl[3]–resulting in epitaxial growth of ZnO containing 0–5% Ga, whereas a polycrystalline ZnO film was produced with 10 mM GaCl[3]. The electrical resistivity of the as-grown ZnO:Ga films varied from 0.2 to 2 Ω cm, but was reduced by two to three orders of magnitude after the films were annealed in air at 300°C. Thus, the lowest resistivity of 7 × 10[4] cm was obtained with an annealed film containing 2.5% Ga, whose carrier concentration and mobility were 7 × 10[20]m[–3] and 13 cm[2] V[–1] s[–1], respectively. Furthermore, even though the non-doped ZnO film was rendered translucent by annealing, ZnO:Ga films with 1.8–4.0% Ga still exhibited transmittance as high as ∼80% in the visible spectrum.

This study investigated the use of novel organic solvent baths for the electrodeposition of aluminum at near-ambient temperatures. It was found that Al metal can be electrodeposited from baths that were composed of 1,3-dimethyl-2-imidazolidinone (DMI) and AlCl 3 , with an AlCl 3 concentration greater than 50 mol%. IR spectroscopy indicated that Al 2 Cl 7 − ions were present in the baths that contained >50 mol% AlCl 3 , where the electrodeposition of Al occurs from Al 2 Cl 7 − ion. The DMI/AlCl 3 baths with AlCl 3 concentrations between 59 and 64 mol% retained a single liquid phase without precipitation at 25 °C, and therefore, they can be used for Al electrodeposition near room temperature. Smooth Al films could be obtained by galvanostatic electrodeposition at 40 °C using a DMI/AlCl 3 bath with the addition of a trace amount of 1,10-phenanthroline.

Hull cell tests were carried out to examine a series of polyethylene amines to evaluate their abilities as brighteners in the electrodeposition of aluminum from a dimethylsulfone (DMSO 2 )-AlCl 3 bath. The tests demonstrated the current density ranges that yielded bright, semi-bright, dull, burnt, and streaked Al deposits from the baths containing each polyethylene amine at a variety of concentrations. Among the amines examined in this study, triethylenetetramine (TETA) was found to be the most effective brightener, providing a bright Al deposit with the highest specular reflectance over a wide range of current densities. No correlation was found between the preferential crystal orientation of the Al and the brightness of the deposit, which along with the acquired scanning electron microscopy images, indicated that surface morphology was primarily responsible for the differences in brightness.