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9 pages, 4330 KiB

Open AccessArticle

Quantitative Analyses of Biofilm by Using Crystal Violet Staining and Optical Reflection

by Ryuto Kamimura, Hideyuki Kanematsu, Akiko Ogawa, Takeshi Kogo, Hidekazu Miura, Risa Kawai, Nobumitsu Hirai, Takehito Kato, Michiko Yoshitake and Dana M. Barry

Materials 2022, 15(19), 6727; https://doi.org/10.3390/ma15196727 - 28 Sep 2022

Cited by 5 | Viewed by 3518

Abstract

Biofilms have caused many problems, not only in the industrial fields, but also in our daily lives. Therefore, it is important for us to control them by evaluating them properly. There are many instrumental analytical methods available for evaluating formed biofilm qualitatively. These [...] Read more.

Biofilms have caused many problems, not only in the industrial fields, but also in our daily lives. Therefore, it is important for us to control them by evaluating them properly. There are many instrumental analytical methods available for evaluating formed biofilm qualitatively. These methods include the use of Raman spectroscopy and various microscopes (optical microscopes, confocal laser microscopes, scanning electron microscopes, transmission electron microscopes, atomic force microscopes, etc.). On the other hand, there are some biological methods, such as staining, gene analyses, etc. From the practical viewpoint, staining methods seem to be the best due to various reasons. Therefore, we focused on the staining method that used a crystal violet solution. In the previous study, we devised an evaluation process for biofilms using a color meter to analyze the various staining situations. However, this method was complicated and expensive for practical engineers. For this experiment, we investigated the process of using regular photos that were quantified without any instruments except for digitized cameras. Digitized cameras were used to compare the results. As a result, we confirmed that the absolute values were different for both cases, respectively. However, the tendency of changes was the same. Therefore, we plan to utilize the changes before and after biofilm formation as indicators for the future. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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12 pages, 4033 KiB

Open AccessArticle

Proposal for Some Affordable Laboratory Biofilm Reactors and Their Critical Evaluations from Practical Viewpoints

by Hikonaru Kudara, Hideyuki Kanematsu, Dana M. Barry, Akiko Ogawa, Takeshi Kogo, Hidekazu Miura, Risa Kawai, Nobumitsu Hirai, Takehito Kato and Michiko Yoshitake

Materials 2022, 15(13), 4691; https://doi.org/10.3390/ma15134691 - 04 Jul 2022

Viewed by 1374

Abstract

Biofilms are a result of bacterial activities and are found everywhere. They often form on metal surfaces and on the surfaces of polymeric compounds. Biofilms are sticky and mostly consist of water. They have a strong resistance to antimicrobial agents and can cause [...] Read more.

Biofilms are a result of bacterial activities and are found everywhere. They often form on metal surfaces and on the surfaces of polymeric compounds. Biofilms are sticky and mostly consist of water. They have a strong resistance to antimicrobial agents and can cause serious problems for modern medicine and industry. Biofilms are composed of extracellular polymeric substances (EPS) such as polysaccharides produced from bacterial cells and are dominated by water at the initial stage. In a series of experiments, using Escherichia coli, we developed three types of laboratory biofilm reactors (LBR) to simulate biofilm formation. For the first trial, we used a rotary type of biofilm reactor for stirring. For the next trial, we tried another rotary type of reactor where the circular plate holding specimens was rotated. Finally, a circular laboratory biofilm reactor was used. Biofilms were evaluated by using a crystal violet staining method and by using Raman spectroscopy. Additionally, they were compared to each other from the practical (industrial) viewpoints. The third type was the best to form biofilms in a short period. However, the first and second were better from the viewpoint of “ease of use”. All of these have their own advantages and disadvantages, respectively. Therefore, they should be properly selected and used for specific and appropriate purposes in the future. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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7 pages, 4655 KiB

Open AccessArticle

Deformation Texture of Bulk Cementite Investigated by Neutron Diffraction

by Nozomu Adachi, Haruki Ueno, Satoshi Morooka, Pingguang Xu and Yoshikazu Todaka

Materials 2022, 15(13), 4485; https://doi.org/10.3390/ma15134485 - 25 Jun 2022

Viewed by 1030

Abstract

Understanding the deformation mechanism of cementite such as on a slip plane is important with regard to revealing and improving the mechanical property of steels. However, the deformation behavior of cementite has not been well investigated because of the difficulty of sample preparation [...] Read more.

Understanding the deformation mechanism of cementite such as on a slip plane is important with regard to revealing and improving the mechanical property of steels. However, the deformation behavior of cementite has not been well investigated because of the difficulty of sample preparation given the single phase structure of cementite. In this study, by fabricating bulk single phase cementite samples using the method developed by the authors, the deformation texture formed by uniaxial compression was investigated using both electron back scatter diffraction and neutron diffraction. The fabricated sample had a random texture before the compression. After applying a compressive strain of 0.5 at 833 K, (010) fiber texture was formed along the compressive axis. It has been suggested from this trend that the primary slip plane of cementite is (010). Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 2086 KiB

Open AccessArticle

Novel Dry Spinning Process of Natural Macromolecules for Sustainable Fiber Material -1- Proof of the Concept Using Silk Fibroin

by Ryo Satoh, Takashi Morinaga and Takaya Sato

Materials 2022, 15(12), 4195; https://doi.org/10.3390/ma15124195 - 13 Jun 2022

Cited by 4 | Viewed by 1961

Abstract

Researchers around the world are developing technologies to minimize carbon dioxide emissions or carbon neutrality in various fields. In this study, the dry spinning of regenerated silk fibroin (RSF) was achieved as a proof of concept for a process using ionic liquids as [...] Read more.

Researchers around the world are developing technologies to minimize carbon dioxide emissions or carbon neutrality in various fields. In this study, the dry spinning of regenerated silk fibroin (RSF) was achieved as a proof of concept for a process using ionic liquids as dissolution aids and plasticizers in developing natural polymeric materials. A dry spinning equipment system combining a stainless-steel syringe and a brushless motor was built to generate fiber compacts from a dope of silk fibroin obtained by degumming silkworm silk cocoons and ionic liquid 1-hexyl-3-methyl-imidazolium chloride ([HMIM][Cl]) according to a general method. The maximum stress and maximum elongation of the RSF fibers were 159.9 MPa and 31.5%, respectively. RSF fibers containing ionic liquids have a homogeneous internal structure according to morphological investigations. Elemental analysis of fiber cross sections revealed the homogeneous distribution of nonvolatile ionic liquid [HMIM][Cl] in RSF fibers. Furthermore, the removal of ionic liquids from RSF fibers through impregnation washing with organic solvents was verified to enhance industrial applications. Tensile testing showed that the fiber strength could be maintained even after removing the ionic liquid. Thermogravimetric analysis results show that the organic solvent 1,1,1,3,3,3-hexafluoro-2-propanol is chemically coordinated to silk fibroin and, as a natural polymer, can withstand heat up to 250 °C. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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8 pages, 1540 KiB

Open AccessArticle

Improved On-Site Characterization of Arsenic in Gypsum from Waste Plasterboards Using Smart Devices

by Masamoto Tafu, Juna Nakamura, Momoka Tanii, Saori Takamatsu and Atsushi Manaka

Materials 2022, 15(7), 2446; https://doi.org/10.3390/ma15072446 - 26 Mar 2022

Cited by 2 | Viewed by 1654

Abstract

The impurities in waste plasterboards, a product of ethical demolition, are a serious problem for their recycling. Plasterboards, the wall materials used in old buildings, are often recycled into gypsum powder for various applications, including ground stabilization. However, this powder contains various chemical [...] Read more.

The impurities in waste plasterboards, a product of ethical demolition, are a serious problem for their recycling. Plasterboards, the wall materials used in old buildings, are often recycled into gypsum powder for various applications, including ground stabilization. However, this powder contains various chemical impurities from the original production process of the gypsum itself, and such impurities pose a risk of polluting the surrounding soil. Here, we present a simple method for verifying the presence of arsenic, a harmful element in recycled gypsum that is suitable for use at demolition sites. First, we developed a simple pretreatment method using a cation-exchange resin to dissolve insoluble gypsum suspended in water by exploiting a chemical equilibrium shift, and we estimated the quantity suitable for releasing the arsenic from arsenic-containing gypsum. This pretreated solution could then be tested with a conventional arsenic test kit by observing the color changes in the test paper using the image sensor of a smart device. This simple method could determine a wide range of arsenic quantities in the gypsum, which would be helpful for monitoring arsenic in recycled gypsum powder, thereby supporting the development of a safe circular economy for waste plasterboards. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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15 pages, 10149 KiB

Open AccessArticle

Tensile Examination and Strength Evaluation of Latewood in Japanese Cedar

by Akihiro Takahashi, Naoyuki Yamamoto, Yu Ooka and Toshinobu Toyohiro

Materials 2022, 15(7), 2347; https://doi.org/10.3390/ma15072347 - 22 Mar 2022

Cited by 1 | Viewed by 1930

Abstract

With the crisis awareness of global warming and natural disasters, utilization of local wood has drawn increasing attention in achieving the Sustainable Development Goals (SDGs). It is necessary to investigate the deformation and fracture of the structural tissue in wood in order to [...] Read more.

With the crisis awareness of global warming and natural disasters, utilization of local wood has drawn increasing attention in achieving the Sustainable Development Goals (SDGs). It is necessary to investigate the deformation and fracture of the structural tissue in wood in order to improve the safety and reliability of wood application. However, deformation and fracture mechanisms of the structural tissue in each annual ring are unknown. The mechanical characteristics of wood are reflected in the properties of earlywood and latewood. In the present study, microstructural observation and tensile tests were conducted to examine the relationship between the mechanical properties and fracture behavior of latewood in the growth direction in Japanese cedar. Brittle fracture behavior of the latewood specimen was confirmed based on the tensile stress–strain curve and features of the fracture surface. Moreover, two fracture modes, tensile fracture and shear fracture, were recognized. Weibull analysis of tensile strength in each fracture mode was performed to evaluate the reliability and utility of brittle latewood. Lastly, two fracture mechanisms were discussed based on the failure observation findings by a scanning electron microscope. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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13 pages, 4656 KiB

Open AccessArticle

Athermal ω Phase and Lattice Modulation in Binary Zr-Nb Alloys

by Mitsuharu Todai, Keisuke Fukunaga and Takayoshi Nakano

Materials 2022, 15(6), 2318; https://doi.org/10.3390/ma15062318 - 21 Mar 2022

Cited by 1 | Viewed by 1879

Abstract

To further explore the potential of Zr-based alloys as a biomaterial that will not interfere with magnetic resonance imaging (MRI), the microstructural characteristics of Zr-xat.% Nb alloys (10 ≤ x ≤ 18), particularly the athermal ω phase and lattice modulation, were investigated by [...] Read more.

To further explore the potential of Zr-based alloys as a biomaterial that will not interfere with magnetic resonance imaging (MRI), the microstructural characteristics of Zr-xat.% Nb alloys (10 ≤ x ≤ 18), particularly the athermal ω phase and lattice modulation, were investigated by conducting electrical resistivity and magnetic susceptibility measurements and transmission electron microscopy observations. The 10 Nb alloy and 12 Nb alloys had a positive temperature coefficient of electrical resistivity. The athermal ω phase existed in 10 Nb and 12 Nb alloys at room temperature. Alternatively, the 14 Nb and 18 Nb alloys had an anomalous negative temperature coefficient of the resistivity. The selected area diffraction pattern of the 14 Nb alloy revealed the co-occurrence of ω phase diffraction and diffuse satellites. These diffuse satellites were represented by g_β + q when the zone axis was [001] or [113], but not [110]. These results imply that these diffuse satellites appeared because the transverse waves consistent with the propagation and displacement vectors were q = <ζ

\bar{ζ}

0>* for the ζ~1/2 and <110> directions. It is possible that the resistivity anomaly was caused by the formation of the athermal ω phase and transverse wave. Moreover, control of the athermal ω-phase transformation and occurrence of lattice modulation led to reduced magnetic susceptibility, superior deformation properties, and a low Young’s modulus in the Zr-Nb alloys. Thus, Zr-Nb alloys are promising MRI-compatible metallic biomaterials. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 4749 KiB

Open AccessArticle

Application of the Sinter-HIP Method to Manufacture Cr–Mo–W–V–Co High-Speed Steel via Powder Metallurgy

by Kazuyuki Furuya, Shiro Jitsukawa and Takayuki Saito

Materials 2022, 15(6), 2300; https://doi.org/10.3390/ma15062300 - 20 Mar 2022

Cited by 5 | Viewed by 2042

Abstract

1.2C–4Cr–4Mo–10W–3.5V–10Co–Fe high-speed steel (JIS SKH57; ISO HS10-4-3-10) is often manufactured via casting and forging. By applying powder metallurgy, the properties of the abovementioned material can be improved. In this study, the effects of sintering conditions on the formation of precipitates and pores are [...] Read more.

1.2C–4Cr–4Mo–10W–3.5V–10Co–Fe high-speed steel (JIS SKH57; ISO HS10-4-3-10) is often manufactured via casting and forging. By applying powder metallurgy, the properties of the abovementioned material can be improved. In this study, the effects of sintering conditions on the formation of precipitates and pores are evaluated. Additionally, strength with and without hydrostatic pressure during sintering is evaluated via static bending and impact tests. Sintering via hot isostatic pressing (HIP) at 1463 K can effectively eliminate pores and prevent the coarsening of precipitates. Toughness and strength improved by 50% by applying HIP. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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8 pages, 2503 KiB

Open AccessArticle

Simple Methods for Evaluating Acid Permeation and Biofilm Formation Behaviors on Polysiloxane Films

by Nobumitsu Hirai, Masaya Horii, Takeshi Kogo, Akiko Ogawa, Daisuke Kuroda, Hideyuki Kanematsu, Junji Nakata and Shigeru Katsuyama

Materials 2022, 15(6), 2272; https://doi.org/10.3390/ma15062272 - 19 Mar 2022

Viewed by 1373

Abstract

The sulfuric acid permeation and biofilm formation behaviors of polysiloxane films have been investigated, and simple methods for evaluating the sulfuric acid permeation and biofilm formation behaviors have been proposed in this paper. The polysiloxane films used in these experiments were practically impermeable [...] Read more.

The sulfuric acid permeation and biofilm formation behaviors of polysiloxane films have been investigated, and simple methods for evaluating the sulfuric acid permeation and biofilm formation behaviors have been proposed in this paper. The polysiloxane films used in these experiments were practically impermeable to the aqueous sulfuric acid solution, and the amount of biofilm formation varied depending on the composition of the films. Further, the amount of sulfuric acid permeation can be estimated by measuring the polarization curves of polysiloxane films with different thicknesses formed on iron electrodes. By measuring the adhesion work of pure water and simulated biofilm droplets on polysiloxane films of different compositions, we can estimate the resistance of biofilm formation on the polysiloxane films. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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17 pages, 4611 KiB

Open AccessArticle

Characteristics of Vibrating Fluidization and Transportation for Al₂O₃ Powder

by Koichiro Ogata, Tsutomu Harada, Hideo Kawahara, Kazuki Tokumaru, Riho Abe, Eiji Mitani and Koji Mitani

Materials 2022, 15(6), 2191; https://doi.org/10.3390/ma15062191 - 16 Mar 2022

Cited by 2 | Viewed by 1595

Abstract

This study focused on the vibrating fluidized-bed-type powder feeder used in HVAF thermal spraying equipment. This feeder has been used in thermal spraying equipment and industrial applications. However, particulate materials’ flow mechanism and stable transport characteristics have not been fully understood. This study [...] Read more.

This study focused on the vibrating fluidized-bed-type powder feeder used in HVAF thermal spraying equipment. This feeder has been used in thermal spraying equipment and industrial applications. However, particulate materials’ flow mechanism and stable transport characteristics have not been fully understood. This study experimentally investigated the fluidization characteristics, powder dispersion state, and powder transportation characteristics of Al₂O₃ particles during vertical vibration fluidization. The material used was Al₂O₃ particles of 2.9 μm and 3808 kg/m³, classified as the group C particles in the Geldart diagram. As experimental conditions, the fluidized air velocity to the bottom of the powder bed and the vibration intensity in the vertical direction changed. The critical fluidization air velocity was defined to evaluate the generating powder flow by vertical vibrating fluidization. As a result, good fluidization of the powder bed of Al₂O₃ was obtained by the vertical vibration, as well as an airflow that was higher than the critical fluidization air velocity. Regarding powder transportation characteristics, it was clarified that the fluidized air velocity at the bottom of the powder dispersion vessel and the pressure difference from the powder dispersion vessel to the transportation part significantly affect the mass flow rate. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 2065 KiB

Open AccessArticle

Mechanical and Lubrication Properties of Double Network Ion Gels Obtained by a One-Step Process

by Hiroyuki Arafune, Yuma Watarai, Toshio Kamijo, Saika Honma and Takaya Sato

Materials 2022, 15(6), 2113; https://doi.org/10.3390/ma15062113 - 13 Mar 2022

Cited by 1 | Viewed by 1781

Abstract

Human joints support us to reduce the impact on our body and move them smoothly. As they are composed of gel-like structures, gel materials with soft and resilient properties are expected, as lubricants, to provide high efficiency and a long lifetime for mechanical [...] Read more.

Human joints support us to reduce the impact on our body and move them smoothly. As they are composed of gel-like structures, gel materials with soft and resilient properties are expected, as lubricants, to provide high efficiency and a long lifetime for mechanical parts. While double network gels including ionic liquids as swelling agents possess high mechanical strength and stable low friction under high temperature or vacuum, their fabrication process is complex and time-consuming. In this study, we applied one-pot synthesis to a double network ion gel (DNIG) to obtain a thin gel film by a simple coating method and examined its thermal, mechanical and tribological properties. The DNIG was obtained by one-pot synthesis (DNIG-1) combining polycondensation of tetraethoxysilane and radical polymerization of methyl methacrylate to form silica and poly(methyl methacrylate) as a 1st and 2nd network, respectively. Such obtained DNIG-1 was characterized and compared with DNIG obtained by a conventional two-step process (DNIG-2). Thermogravimetric analysis and the compressive stress–strain test showed high thermal stability and mechanical strength of DNIG-1. As friction at the glass/DNIG-1 interface showed high friction compared with that at glass/DNIG-2, various counterface materials were applied to examine their effect on the friction of DNIG-1. As SUS304/DNIG-1 showed much lower friction compared with glass/DNIG-1, the difference in the friction was presumably due to the different adsorption forces and compatibility between the materials. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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20 pages, 7480 KiB

Open AccessArticle

Solid-State-Activated Sintering of ZnAl₂O₄ Ceramics Containing Cu₃Nb₂O₈ with Superior Dielectric and Thermal Properties

by Koichi Shigeno, Takuma Yano and Hirotaka Fujimori

Materials 2022, 15(5), 1770; https://doi.org/10.3390/ma15051770 - 26 Feb 2022

Cited by 1 | Viewed by 1932

Abstract

Low-temperature co-fired ceramics (LTCCs) are dielectric materials that can be co-fired with Ag or Cu; however, conventional LTCC materials are mostly poorly thermally conductive, which is problematic and requires improvement. We focused on ZnAl₂O₄ (gahnite) as a base material. With [...] Read more.

Low-temperature co-fired ceramics (LTCCs) are dielectric materials that can be co-fired with Ag or Cu; however, conventional LTCC materials are mostly poorly thermally conductive, which is problematic and requires improvement. We focused on ZnAl₂O₄ (gahnite) as a base material. With its high thermal conductivity (~59 W·m⁻¹·K⁻¹ reported for 0.83ZnAl₂O₄–0.17TiO₂), ZnAl₂O₄ is potentially more thermally conductive than Al₂O₃ (alumina); however, it sinters densely at a moderate temperature (~1500 °C). The addition of only 4 wt.% of Cu₃Nb₂O₈ significantly lowered the sintering temperature of ZnAl₂O₄ to 910 °C, which is lower than the melting point of silver (961 °C). The sample fired at 960 °C for 384 h exhibited a relative permittivity (ε_r) of 9.2, a quality factor by resonant frequency (Q × f) value of 105,000 GHz, and a temperature coefficient of the resonant frequency (τ_f) of −56 ppm·K⁻¹. The sample exhibited a thermal conductivity of 10.1 W·m⁻¹·K⁻¹, which exceeds that of conventional LTCCs (~2–7 W·m⁻¹·K⁻¹); hence, it is a superior LTCC candidate. In addition, a mixed powder of the Cu₃Nb₂O₈ additive and ZnAl₂O₄ has a melting temperature that is not significantly different from that (~970 °C) of the pristine Cu₃Nb₂O₈ additive. The sample appears to densify in the solid state through a solid-state-activated sintering mechanism. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 4538 KiB

Open AccessArticle

Properties of Magnetic Garnet Films for Flexible Magneto-Optical Indicators Fabricated by Spin-Coating Method

by Ryosuke Hashimoto, Toshiya Itaya, Hironaga Uchida, Yuya Funaki and Syunsuke Fukuchi

Materials 2022, 15(3), 1241; https://doi.org/10.3390/ma15031241 - 07 Feb 2022

Cited by 4 | Viewed by 1865

Abstract

Non-destructive testing using a magneto-optical effect is a high-resolution non-destructive inspection technique for a metallic structure. It is able to provide high-spatial resolution images of defects. Previously, it has been difficult to fabricate flexible magneto-optical sensors because thermal treatment is necessary to crystallize [...] Read more.

Non-destructive testing using a magneto-optical effect is a high-resolution non-destructive inspection technique for a metallic structure. It is able to provide high-spatial resolution images of defects. Previously, it has been difficult to fabricate flexible magneto-optical sensors because thermal treatment is necessary to crystallize the magnetic garnet. Therefore, it was not possible to apply magneto-optical imaging to complicated shapes in a test subject, such as a curved surface. In this study, we developed a new process for deposition of the magnetic garnet on the flexible substrate by applying the magnetic garnet powders that have already undergone crystallization. In this new process, as it does not require thermal treatment after deposition, flexible substrates with low heat resistance can be used. In this paper, we report our observations of the optical properties, magnetic hysteresis loop, crystallizability and density of the particles on the flexible substrate deposited by the spin-coating method. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 1920 KiB

Open AccessArticle

Morphology Control of Monomer–Polymer Hybrid Electron Acceptor for Bulk-Heterojunction Solar Cell Based on P3HT and Ti-Alkoxide with Ladder Polymer

by Yasuyuki Ueda, Yuki Kurokawa, Kei Nishii, Hideyuki Kanematsu, Tadashi Fukumoto and Takehito Kato

Materials 2022, 15(3), 1195; https://doi.org/10.3390/ma15031195 - 04 Feb 2022

Viewed by 1938

Abstract

We report the morphology control of a nano-phase-separated structure in the photoactive layer (power generation layer) of organic–inorganic hybrid thin-film solar cells to develop highly functional electronic devices for societal applications. Organic and inorganic–organic hybrid bulk heterojunction solar cells offer several advantages, including [...] Read more.

We report the morphology control of a nano-phase-separated structure in the photoactive layer (power generation layer) of organic–inorganic hybrid thin-film solar cells to develop highly functional electronic devices for societal applications. Organic and inorganic–organic hybrid bulk heterojunction solar cells offer several advantages, including low manufacturing costs, light weight, mechanical flexibility, and a potential to be recycled because they can be fabricated by coating them on substrates, such as films. In this study, by incorporating the carrier manager ladder polymer BBL as the third component in a conventional two-component power generation layer consisting of P3HT—the conventional polythiophene derivative and titanium alkoxide—we demonstrate that the phase-separated structure of bulk heterojunction solar cells can be controlled. Accordingly, we developed a discontinuous phase-separated structure suitable for charge transport, obtaining an energy conversion efficiency higher than that of the conventional two-component power generation layer. Titanium alkoxide is an electron acceptor and absorbs light with a wavelength lower than 500 nm. It is highly sensitive to LED light sources, including those used in homes and offices. A conversion efficiency of 4.02% under a 1000 lx LED light source was achieved. Hence, high-performance organic–inorganic hybrid bulk heterojunction solar cells with this three-component system can be used in indoor photovoltaic systems. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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18 pages, 11019 KiB

Open AccessArticle

Self-Pierce Riveting of Three Thin Sheets of Aluminum Alloy A5052 and 980 MPa Steel

by Satoshi Achira, Yohei Abe and Ken-ichiro Mori

Materials 2022, 15(3), 1010; https://doi.org/10.3390/ma15031010 - 28 Jan 2022

Cited by 9 | Viewed by 2430

Abstract

Self-pierce riveting of three thin sheets of 980 MPa steel and 5052 aluminum alloy was performed to investigate the effect of sheet configuration on the deforming behaviors of the sheets and the rivet and joint strength. When the lower sheet was aluminum alloy, [...] Read more.

Self-pierce riveting of three thin sheets of 980 MPa steel and 5052 aluminum alloy was performed to investigate the effect of sheet configuration on the deforming behaviors of the sheets and the rivet and joint strength. When the lower sheet was aluminum alloy, the joining range was relatively wide, i.e., the interlock hooking the rivet leg tended to be large. In the sheet configuration in which the upper and lower sheets were A5052 and the middle sheet was 980 MPa steel, the rivet leg spread out moderately and the joint without defects was obtained. In the lower 980 MPa steel sheet, fracture tended to occur due to the low ductility of the lower sheet, and the joining range was narrow with the small interlock although the three sheets were joined by an appropriate die shape. In joint strength of joined three sheets, fracture occurred in the lower-strength aluminum alloy sheet if interlocks of about 300 μm and 150 μm could be formed in the lower aluminum alloy sheet and 980 MPa steel sheet, respectively. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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11 pages, 8562 KiB

Open AccessArticle

Effect of Sb and Zn Addition on the Microstructures and Tensile Properties of Sn–Bi-Based Alloys

by Akira Yamauchi and Masashi Kurose

Materials 2022, 15(3), 884; https://doi.org/10.3390/ma15030884 - 24 Jan 2022

Cited by 6 | Viewed by 2086

Abstract

The tensile behavior of Sn–Bi–Cu and Sn–Bi–Ni alloys has been widely investigated. Reportedly, the addition of small amounts of a third element can refine the microstructures of the eutectic Sn-58mass% Bi solder and improve its ductility. However, the superplasticity mechanism of Sn-based alloys [...] Read more.

The tensile behavior of Sn–Bi–Cu and Sn–Bi–Ni alloys has been widely investigated. Reportedly, the addition of small amounts of a third element can refine the microstructures of the eutectic Sn-58mass% Bi solder and improve its ductility. However, the superplasticity mechanism of Sn-based alloys has not been clearly established. Therefore, in this study, the effects of Sb and Zn addition on the microstructures and tensile properties of Sn–Bi-based alloys were investigated. The alloys were subjected to tensile tests under various strain rates and temperatures. We found that Zn- and Sb-added Sn–Bi-based alloys demonstrated superplastic deformation at high temperatures and low strain rates. Sb addition significantly affected the elongation of the Sn–Bi–Sb alloys because the metal dissolves in both the primary Sn phase and the eutectic Sn–Bi matrix. The segregation of Zn and formation of needle-like Zn particles at the eutectic Sn–Bi phase boundary affected the superplastic deformation of the alloys. The deformation of the Sn–40Bi-based alloys at high temperatures and low strain rates led to dynamic recovery, dynamic recrystallization, and/or grain boundary slip because of the accumulation of voids. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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13 pages, 17730 KiB

Open AccessArticle

Copper Surface Treatment Method with Antibacterial Performance Using “Super-Spread Wetting” Properties

by Beomdeok Seo, Hideyuki Kanematsu, Masashi Nakamoto, Yoshitsugu Miyabayashi and Toshihiro Tanaka

Materials 2022, 15(1), 392; https://doi.org/10.3390/ma15010392 - 05 Jan 2022

Cited by 6 | Viewed by 2497

Abstract

In this work, a copper coating is developed on a carbon steel substrate by exploiting the superwetting properties of liquid copper. We characterize the surface morphology, chemical composition, roughness, wettability, ability to release a copper ion from surfaces, and antibacterial efficacy (against Escherichia [...] Read more.

In this work, a copper coating is developed on a carbon steel substrate by exploiting the superwetting properties of liquid copper. We characterize the surface morphology, chemical composition, roughness, wettability, ability to release a copper ion from surfaces, and antibacterial efficacy (against Escherichia coli and Staphylococcus aureus). The coating shows a dense microstructure and good adhesion, with thicknesses of approximately 20–40 µm. X-ray diffraction (XRD) analysis reveals that the coated surface structure is composed of Cu, Cu₂O, and CuO. The surface roughness and contact angle measurements suggest that the copper coating is rougher and more hydrophobic than the substrate. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements reveal a dissolution of copper ions in chloride-containing environments. The antibacterial test shows that the copper coating achieves a 99.99% reduction of E. coli and S. aureus. This study suggests that the characteristics of the copper-coated surface, including the chemical composition, high surface roughness, good wettability, and ability for copper ion release, may result in surfaces with antibacterial properties. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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11 pages, 3998 KiB

Open AccessFeature PaperArticle

Lithium-Ion-Conducting Ceramics-Coated Separator for Stable Operation of Lithium Metal-Based Rechargeable Batteries

by Ryo Shomura, Ryota Tamate and Shoichi Matsuda

Materials 2022, 15(1), 322; https://doi.org/10.3390/ma15010322 - 03 Jan 2022

Cited by 7 | Viewed by 2970

Abstract

Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the [...] Read more.

Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the interface between Li metal and an electrolyte, a facile and scalable blade coating method was used to cover the commercial polyethylene membrane separator with an inorganic/organic composite solid electrolyte layer containing lithium-ion-conducting ceramic fillers. The coated separator suppressed the interfacial resistance between the Li metal and the electrolyte and consequently prolonged the cycling stability of deposition/dissolution processes in Li/Li symmetric cells. Furthermore, the effect of the coating layer on the discharge/charge cycling performance of lithium-oxygen batteries was investigated. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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15 pages, 3578 KiB

Open AccessArticle

Tool for Designing Breakthrough Discovery in Materials Science

by Michiko Yoshitake

Materials 2021, 14(22), 6946; https://doi.org/10.3390/ma14226946 - 17 Nov 2021

Cited by 2 | Viewed by 1955

Abstract

A database of material property relationships, which serves as a scientific principles database, and a database search system are proposed and developed. The use of this database can support a broader research perspective, which is increasingly important in the era of automated computer-aided [...] Read more.

A database of material property relationships, which serves as a scientific principles database, and a database search system are proposed and developed. The use of this database can support a broader research perspective, which is increasingly important in the era of automated computer-aided experimentation and machine learning of experimental and calculated data. Examples of the wider use of scientific principles in materials research are presented. The database and its advantages are described. An implementation of the proposed database and search system as a prototype software is reported. The usefulness of the database and search system is demonstrated by an example of a surprising but reasonable discovery. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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9 pages, 15149 KiB

Open AccessArticle

High-Resolution Mapping of Local Photoluminescence Properties in CuO/Cu₂O Semiconductor Bi-Layers by Using Synchrotron Radiation

by Masakazu Kobayashi, Masanobu Izaki, Pei Loon Khoo, Tsutomu Shinagawa, Akihisa Takeuchi and Kentaro Uesugi

Materials 2021, 14(19), 5570; https://doi.org/10.3390/ma14195570 - 25 Sep 2021

Cited by 1 | Viewed by 1573

Abstract

The quality of a semiconductor, which strongly affects its performance, can be estimated by its photoluminescence, which closely relates to the defect and impurity energy levels. In light of this, it is necessary to have a measurement method for photoluminescence properties with spatial [...] Read more.

The quality of a semiconductor, which strongly affects its performance, can be estimated by its photoluminescence, which closely relates to the defect and impurity energy levels. In light of this, it is necessary to have a measurement method for photoluminescence properties with spatial resolution at the sub-micron or nanoscale. In this study, a mapping method for local photoluminescence properties was developed using a focused synchrotron radiation X-ray beam to evaluate localized photoluminescence in bi-layered semiconductors. CuO/Cu₂O/ZnO semiconductors were prepared on F:SnO₂/soda-lime glass substrates by means of electrodeposition. The synchrotron radiation experiment was conducted at the beamline 20XU in the Japanese synchrotron radiation facility, SPring-8. By mounting the high-sensitivity spectrum analyzer near the edge of the CuO/Cu₂O/ZnO devices, luminescence maps of the semiconductor were obtained with unit sizes of 0.3 μm × 0.3 μm. The devices were scanned in 2D. Light emission 2D maps were created by classifying the obtained spectra based on emission energy already reported by M. Izaki, et al. Band-like structures corresponding to the stacking layers of CuO/Cu₂O/ZnO were visualized. The intensities of emissions at different energies at each position can be associated with localized photovoltaic properties. This result suggests the validity of the method for investigation of localized photoluminescence related to the semiconductor quality. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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Review

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44 pages, 3877 KiB

Open AccessReview

Magnetic Adsorbents for Wastewater Treatment: Advancements in Their Synthesis Methods

by Vanpaseuth Phouthavong, Ruixin Yan, Supinya Nijpanich, Takeshi Hagio, Ryoichi Ichino, Long Kong and Liang Li

Materials 2022, 15(3), 1053; https://doi.org/10.3390/ma15031053 - 29 Jan 2022

Cited by 17 | Viewed by 3603

Abstract

The remediation of water streams, polluted by various substances, is important for realizing a sustainable future. Magnetic adsorbents are promising materials for wastewater treatment. Although numerous techniques have been developed for the preparation of magnetic adsorbents, with effective adsorption performance, reviews that focus [...] Read more.

The remediation of water streams, polluted by various substances, is important for realizing a sustainable future. Magnetic adsorbents are promising materials for wastewater treatment. Although numerous techniques have been developed for the preparation of magnetic adsorbents, with effective adsorption performance, reviews that focus on the synthesis methods of magnetic adsorbents for wastewater treatment and their material structures have not been reported. In this review, advancements in the synthesis methods of magnetic adsorbents for the removal of substances from water streams has been comprehensively summarized and discussed. Generally, the synthesis methods are categorized into five groups, as follows: direct use of magnetic particles as adsorbents, attachment of pre-prepared adsorbents and pre-prepared magnetic particles, synthesis of magnetic particles on pre-prepared adsorbents, synthesis of adsorbents on preprepared magnetic particles, and co-synthesis of adsorbents and magnetic particles. The main improvements in the advanced methods involved making the conventional synthesis a less energy intensive, more efficient, and simpler process, while maintaining or increasing the adsorption performance. The key challenges, such as the enhancement of the adsorption performance of materials and the design of sophisticated material structures, are discussed as well. Full article

(This article belongs to the Special Issue Advanced Materials for Societal Implementation)

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