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Plasma-Metal Inert Gas (MIG) hybrid welding was employed to carry out bead on plate welding of an aluminum alloy A5052. The plasma arc was ignited to form a keyhole, and a series of welding systems were developed starting with MIG welding. The convective patterns within the weld pool were meticulously analyzed. In addition, we conducted experimental observations of the flow inside and on the surface of the pool, and we were able to visualize the flow in some areas. The results indicated that the plasma welding side formed a pool that seamlessly integrated the plasma side and the MIG side. At the same time, we observed the formation of a flow pool that integrates both plasma and MIG sides, affecting the formation and behavior of the weld pool. This study aims to provide a nuanced understanding of flow dynamics across the entire pool. This approach is geared towards refining the intricacies of weld pool dynamics for the advancement of welding technologies.

Glass cullet (GC) generated from the disposal of photovoltaic (PV) panels are typically landfilled, and effective GC utilization methods must be established for PV generation. In this study, alkali-activated material (AAM) mortars were prepared from the paste of fine blast-furnace slag powder, fly ash, and sodium orthosilicate (SO) and mixed with crushed sand and GC to investigate the potential use of GC as a fine aggregate in AAM. The replacement of crushed sand with GC did not considerably affect the flowability of the mortar, whereas the compressive strength decreased with the increasing GC replacement rates. Although expansion due to the alkali–silica reaction (ASR) was observed in mortars wherein GC replaced crushed sand, the expansion can be controlled by reducing the amount of mixed SO, autoclaving the GC, performing preleaching to remove the Si that causes the ASR, and replacing the blast-furnace slag with fly ash. By enforcing measures against the expansion, the possibility of using GC as fine aggregate is enhanced considerably, thus increasing the feasibility of continuous PV production.

Tide-embankment walls protecting coastal roads frequently contain numerous windows so that pedestrians and drivers can view the scenery without experiencing reduced sunlight. Tide-embankment windows must withstand extreme climatic conditions. However, the effects of temperature extremes on acrylic boards have rarely been studied. This paper proposes a simple method for constructing a high-temperature environment and a method for measuring strain on an acrylic plate. The deformation and strain of a 40-mm-thick acrylic tide-embankment window were determined experimentally and numerically in this study in a high-temperature environment, obtaining similar results; additionally, the numerical method was subsequently used to simulate a low-temperature environment. Because thermal conductivity was low, the internal temperature of the thick acrylic board did not immediately change with the temperature of the surface, and thermal expansion and contraction of the board were restrained. Temperature-induced deformation effects were low across the entire range of temperatures and heating rates recorded in coastal Japan.

“Akahoya” is a volcanic soil classified as a special soil deposited in Kyushu, Japan. Many of its properties are not yet clearly understood. We found that Akahoya had the potential to adsorb bacteria in cattle feces, which prompted us to investigate its material properties and perform experiments to comprehensively evaluate its adsorption performance for various fine particles such as acidic and basic dyes, NOx/SOx gas, and phosphoric acid ions, in addition to bacteria. Akahoya had a very high specific surface area owing to the large number of nanometer-sized pores in its structure; it exhibited a high adsorption capacity for both NO2 and SO2. Regarding the zeta potential of Akahoya, the point of zero charge was approximately pH 7.0. The surface potential had a significant effect on the adsorption of acidic and basic dyes. Akahoya had a very high cation exchange capacity when the sample surface was negatively charged and a high anion exchange capacity when the sample surface was positively charged. Akahoya also exhibited a relatively high adsorption capacity for phosphoric acid because of its high level of Al2O3, and the immersion liquid had a very high Al ion concentration. Finally, filtration tests were performed on Escherichia coli suspension using a column filled with Akahoya or another volcanic soil sample. The results confirmed that the Escherichia coli adhered on the Akahoya sample. The results of the Escherichia coli release test, after the filtration test, suggested that this adhesion to Akahoya could be phosphorus-mediated.

To utilize waste glass fiber-reinforced plastic (GFRP), we have created porous ceramics by mixing crushed GFRP with clay and then firing the resultant mixture. Some GFRP/clay ceramics have great porosity, which allows water to pass through them. In this study, by exploiting the high strength and water permeability of GFRP/clay ceramics, we aimed to develop water-permeable paving blocks that could prevent the inundation of roads by sudden heavy rains in urban areas. Various specimens were made by adjusting the mixing ratio of clay and crushed GFRP (40–60 mass%), the GFRP particle size, and the firing temperature. Bending strength, compressive strength, and permeability tests were then carried out on the samples. The obtained values were compared with those of porous ceramics made by mixing plastic without glass fiber and clay before firing. First, the difference in the porosity and strength of GFRP/clay ceramics and porous ceramics without glass fiber was clarified. Then, the manufacturing conditions of ceramics that satisfy both strength and permeability criteria were clarified for water-permeable paving blocks.

To reuse waste glass fiber-reinforced plastics (GFRPs), porous ceramics (i.e., GFRP/clay ceramics) were produced by mixing crushed GFRP with clay followed by firing the resulting mixture under different conditions. The possibility of using ceramics fired under a reducing atmosphere as adsorbent materials to remove NOx and SOx from combustion gases of fossil fuels was investigated because of the high porosity, specific surface area, and contents of glass fibers and plastic carbides of the ceramics. NO2 and SO2 adsorption tests were conducted on several types of GFRP/clay ceramic samples, and the gas concentration reduction rates were compared to those of a clay ceramic and a volcanic pumice with high NO2 adsorption. In addition, to clarify the primary factor affecting gas adsorption, adsorption tests were conducted on the glass fibers in the GFRP and GFRP carbides. The reductively fired GFRP/clay ceramics exhibited high adsorption performance for both NO2 and SO2. The primary factor affecting the NO2 adsorption of the ceramics was the plastic carbide content in the clay structure, while that affecting the SO2 adsorption of the ceramics was the glass fiber content.

The effective reuse of waste glass fiber-reinforced plastic (GFRP) is desired. We previously produced porous ceramics by firing mixtures of crushed GFRP and clay in a reducing atmosphere and demonstrated their applicability as adsorbents for the removal of basic dyes from dyeing wastewater. However, the primary influencing factors and the dye adsorption mechanism have not been fully elucidated, and the adsorption of acidic and direct dyes has not been clarified. In this study, adsorption tests were conducted, and the effects of the firing atmosphere, specific surface area, type of dye, and individual components were comprehensively investigated. The results showed that reductively fired ceramics containing plastic carbide residue adsorbed basic dye very well but did not adsorb acidic dye well. The clay structure was the primary factor for the dye adsorption rather than the GFRP carbide. The mechanism for the basic dye adsorption appears to have been an increase in specific surface area due to the plastic carbide residue in the ceramic structure, which increased the ion exchange between the clay minerals and the dye. By adjusting the pH of the aqueous solution, the GFRP/clay ceramic also adsorbed considerable amounts of direct dye, so the mechanism was determined to be ion exchange with the calcium component of the glass fibers.

We investigated the use of waste glass fiber-reinforced plastic (GFRP) to remove dye from industrial wastewater. The dye adsorbent material, based on GFRP/clay ceramics, was produced by mixing crushed GFRP with clay and firing the resulting mixture. Several types of ceramics were produced by adjusting the mixing ratio of clay, crushed 40% GF/GFRP, and firing atmosphere. Adsorption tests with methylene blue (MB) dye were performed by mixing the ceramics into an MB solution while controlling the stirring speed and measuring the decrease in MB dye concentration over time. These results showed that GFRP/clay ceramics reductively fired at 1073 K had a higher MB dye adsorption ability than that of the clay ceramic. The MB dye absorptivity of the reductively fired ceramics increased as we increased the mixing ratio of GFRP. We attribute this result to the high plastic carbide content in the ceramic, which has excellent dye absorbability. Furthermore, these particles had a comparatively high specific surface area and porosity.

This study is aimed at the development of civil engineering materials such as pavement blocks and building tiles that can moderate the heat island phenomenon. This is achieved by exploiting properties such as the material porous structure, high water absorption capacity and high strength of ceramics produced by mixing clay and crushed waste glass fiber-reinforced plastic (GFRP) before firing. Fundamental properties, such as pore size distribution, water absorption capacity, solution pH after ceramic immersion, bending strength, freezing resistance performance and thermal conductivity of ceramic specimens with varying ratios of clay and GFRP were clarified. The radiant heat reduction performance of the ceramic was examined by measuring the surface temperatures of a ceramic sample made from clay, a ceramic sample made by mixing 20% GFRP with clay, and a mortar sample in water-saturated and dry states while their surfaces were irradiated with infrared light. To clarify the difference in temperature-reducing ability by evaporation heat on each sample, the amount of water evaporated from a sample that had absorbed water and was irradiated with infrared light was measured. The rate of heat-absorption from the sample by water evaporation was estimated. The temperature-reducing effect by evaporation heat of the sample during water-absorption was verified quantitatively by thermal conductivity analysis using finite element methods. While water-saturated, a 20% GFRP/clay ceramic sample could reduce the increase in temperature caused by radiant heat considerably, and for an extended duration. It is expected that such ceramics could be used in civil engineering materials to counteract the heat island phenomenon.

To recycle silica byproducts and to moderate the heat-island phenomenon, a porous ceramic was prepared by mixing waste silica powder with clay, and then firing the resultant mixture. By exploiting the high water-absorption capacity of the resulting ceramic, a greening material in which the porous ceramic was covered with moss was produced. The suppression effect of the temperature increase caused by solar-radiant heat on the moss-covered ceramic, was investigated quantitatively using the following procedure. First, the surface temperature change of the water-absorbing moss-covered sample during solar-radiant heat reception, and the amount of water that evaporated from the sample were measured simultaneously. Then, the heat of evaporation was estimated from measurements of the rate of water evaporation. Next, to investigate how much the sample temperature was reduced by heat of water evaporation, the temperature change of the sample when the heat of water evaporation was absorbed from the sample, was simulated by performing Finite Element Method (FEM) analysis. The summary of the results was as follows. (1) The primary factor of the temperature-reduction-effects on the moss-covered sample was action of heat of water evaporation. Therefore, the moss-covered sample did not exhibit much of the suppression ability of the temperature increase caused by solar-radiant heat, when the sample did not contain sufficient water. (2) This analytical method enabled us to simulate with a relatively high accuracy, the temperature change of a water-absorbing sample during solar-radiant-heat reception. Especially, the method enabled us to investigate visibly the influence of water evaporation-heat on the sample temperature, in addition to the influences of the emissivity of the sample, and the apparent specific heat and thermal conductivity changes due to water content in the sample.

Akahoya is a volcanic soil rich in alumina, primarily deposited in Kyushu, Japan. We have found that Akahoya adsorbs bacteria in the water surrounding cattle grazing areas, suggesting a potential for environmental purification. This study investigated the spectrum of microorganisms adsorbed by Akahoya using a column filled with Akahoya through which a suspension of microorganisms was passed. Shirasu soil, another volcanic soil with a different chemical composition, was used as a control. Akahoya effectively adsorbed a diverse range of microorganisms including Escherichia coli, Campylobacter jejuni, Vibrio parahaemolyticus, Salmonella Enteritidis, Staphylococcus aureus, Clostridium perfringens, spores of Bacillus subtilis and Bacillus anthracis, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), murine norovirus, and avian influenza virus (H3N2), whereas Shirasu soil did not adsorb any of the organisms examined. Moreover, bacteria naturally present in river water, such as aerobic bacteria, total coliforms, and Enterobacteriaceae as indicators of river contamination, as well as E. coli added artificially to sterilized river water, were reduced to below the detection limit (<1 CFU/mL) after being passed through Akahoya. Additionally, the number of viable E. coli continued to decrease after contact with Akahoya for 1 month, suggesting bactericidal effects. Notably, the adsorption of E. coli to Akahoya was influenced by the concentration of phosphate and the pH of the suspension due to the interaction between the surface phosphorylation of organisms and Al2O3, the major chemical component of Akahoya. The present results demonstrate the remarkable ability of Akahoya to remove phosphate and microbes, suggesting that Akahoya could be used for water purification processes. [ABSTRACT FROM AUTHOR]