【Machine Translation】 Ultrafine bubbles (UFBs) are extremely fine bubbles with a diameter of less than 1 μm. Due to their long-term stability, influenced by Brownian motion, they are increasingly being utilized in industrial applications. However, the measurement of UFBs is affected by the presence of nanoparticles and impurities, making it essential to develop a better understanding of UFB removal and destabilization. This study aims to clarify the characteristics of thermal instability of UFBs by measuring changes in particle size distribution and dissolved oxygen (DO) during heating and cooling processes. UFBs were generated using both the pressurized dissolution method and the strong shear method. After stabilization at 25°C, they were heated for one hour at 40°C, 60°C, 80°C, and 100°C, followed by either slow cooling to room temperature or rapid cooling, to compare their effects. Using nanoparticle tracking analysis, it was observed that the particle size distribution of UFBs changed with heating, with a significant increase in particle size particularly at temperatures above 80°C. The number density of UFBs initially increased due to a reduction in DO caused by heating, but subsequently decreased. Rapid cooling led to a more pronounced decrease in DO, suggesting the secondary generation of UFBs. However, heating also caused UFBs to coalesce, increasing their particle size and ultimately reducing their number density. This study clarifies the relationship between the thermal instability of UFBs and DO levels, providing fundamental insights into the thermal stability of UFBs for industrial applications.

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【Machine Translation】 Milk is a highly nutritious food; however, its quality deteriorates during storage due to exposure to light, heat, and microbial activity. Traditionally, changes in milk components have been evaluated using destructive sampling methods, but quantitative non-destructive analytical techniques remain limited. In this study, we investigated a non-destructive method for measuring the temporal changes in milk components after opening using ultraviolet-visible near-infrared absorption spectroscopy (UV-Vis-NIR), fluorescence spectroscopy (PL), and infrared spectroscopy (ATR-FTIR). In the experiment, commercially available milk was transferred to polystyrene containers and stored at 35°C. Throughout the storage period, visual observations and spectroscopic measurements were conducted to record changes in absorbance at 1740 cm⁻¹ (fat), 1540 cm⁻¹ (protein), and 1038 cm⁻¹ (lactose). The results showed that visible changes occurred after five days, with a decrease in fat and protein absorbance observed from day five onward. However, molecular-level changes were detected earlier, with fat absorbance decreasing from day two and protein absorbance from day three. These findings suggest that early-stage deterioration of milk quality can be detected at the molecular level. This study demonstrates the potential of non-destructive spectroscopic methods for the early detection of milk quality deterioration, which could contribute to safer and higher-quality product management.

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【Machine Translation】 This study aims to improve the reaction efficiency of the photochemical addition of caffeine derivatives by applying platinum-supported titanium dioxide (Pt/TiO₂) as a catalyst. Previously, D. Elad et al. reported that the photochemical addition reaction between caffeine and isopropyl alcohol (i-PrOH) yielded 35% product and required 72 hours of light irradiation. However, improving reaction efficiency remained a challenge. In this study, we investigated the effect of the Pt/TiO₂ catalyst and developed a reaction system using both batch reactions and a microreactor (MCR). In batch reactions, the yield was 2% under freeze degassing and 25% under Ar gas degassing without a catalyst. However, adding the Pt/TiO₂ catalyst increased the yield to 50%. A similar trend was observed when ethanol (EtOH) was used as the solvent instead of i-PrOH. In MCR-based reactions, the presence of Pt/TiO₂ further enhanced the yield, particularly increasing it by 10% in the reaction of 1a. Additionally, the reaction time was significantly reduced from 3 hours in batch reactions to just 1 minute. These results indicate that the introduction of the Pt/TiO₂ catalyst and the use of MCR enable both an increase in yield and a significant reduction in reaction time for the photochemical addition of caffeine derivatives. This study contributes to the further development of organic synthesis using photocatalysts.

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Rhodium is a member of the platinum group of metals, and is used in a wide range of industries, including as a catalyst for treating automobile exhaust gases. With the tightening of environmental regulations in recent years, there is a need for improved technology for recovering rhodium. In this study, we used the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (HMI[TFSI-]) as a carrier in the extraction of rhodium using the emulsion membrane method, and investigated the effect of various operating conditions on extraction efficiency. In the experiment, an external aqueous phase containing rhodium(III) chloride, an organic phase containing HMI[TFSI-], and an internal aqueous phase using Tris as the reverse extractant were used to create a W/O emulsion using a homogenizer, and then an emulsion film (W/O/W emulsion) was formed in a stirring tank, and the concentration of each metal was measured using an atomic absorption spectrophotometer. As a result, the extraction rate of rhodium increased as the concentration of HMI[TFSI-] increased, and an extraction rate of over 80% was obtained under conditions of 50 mM. Furthermore, it was confirmed that the emulsion membrane was most stable and a high extraction rate was obtained when the concentration of the surfactant Span 80 was 5 vol%. This study has shown that the emulsion membrane method using the ionic liquid HMI[TFSI-] as a carrier is effective for the high-efficiency recovery of rhodium. This method is expected to contribute to the effective use of precious metal resources.

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【Machine Translation】 Differentiation and integration methods are commonly used to calculate reaction rates, but they suffer from issues such as assumptions about reaction order and errors due to graphical differentiation. To address these problems, Nagata proposed a reaction rate calculation method using the Weibull distribution, demonstrating its applicability to first-order reactions. However, this method has low correlation with experimental data for non-first-order reactions. In this study, we polynomialized the Weibull function to examine its applicability to second-order and bimolecular reactions. Experiments were conducted using the saponification reaction of ethyl acetate with an alkali as a model system, measuring the relationship between reactant concentration and time. The obtained data were applied to the polynomial Weibull function, and parameters were determined through multiple regression analysis. Reaction rates were then derived and compared with the true reaction order. For second-order reactions, the correct reaction order was predicted in two out of three trials. However, for bimolecular reactions, significant errors were observed. To investigate the cause, we conducted an analysis using simulated data with minimal error, revealing that multiple regression analysis was the main factor causing outliers. The results of this study indicate that polynomialization of the Weibull function is effective for calculating reaction rates in second-order reactions, but further improvements are needed for its application to bimolecular reactions.

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【Machine Translation】 Ishizuchi Black Tea is one of the four rare post-fermented teas in Japan, produced through a traditional two-step fermentation process. In recent years, its health benefits have attracted attention, particularly its antioxidant properties. This study focused on theabrownin, a component of Ishizuchi Black Tea, to clarify its antioxidant activity. Ishizuchi Black Tea harvested and fermented in 2022 was used as a sample, with Yame Green Tea as a reference. The tea leaves were extracted using both hard and soft water, and theabrownin was purified by liquid-liquid extraction and vacuum drying. Antioxidant activity was evaluated using the ORAC method by measuring absorbance changes in a phosphate buffer containing fluorescein and 2,2'-azobis(2-methylpropionamidine) dihydrochloride with a UV-Vis spectrophotometer. The results showed that both Ishizuchi Black Tea and green tea exhibited antioxidant activity, independent of water hardness. However, the theabrownin solution (12 mg/100 mL) did not show antioxidant activity, suggesting that the contribution of theabrownin alone is minimal. These findings indicate that the antioxidant effects of Ishizuchi Black Tea are likely due to synergistic interactions among multiple components rather than theabrownin alone. This study contributes to the understanding of the health benefits of Ishizuchi Black Tea, highlighting the need for further investigation into its active components and mechanisms of action.

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【Machine Translation】 Milk whey, a byproduct of yogurt and cheese production, contains proteins such as α-lactalbumin (α-LA) and β-lactoglobulin (β-LG). While α-LA is known for its high digestibility and potential health benefits, β-LG is absent in human breast milk and is considered a major allergen for infants. Therefore, selective removal of β-LG from milk whey is necessary; however, current separation techniques are costly and limited to large-scale industries. This study investigated a precipitation-based separation method using surfactants to effectively separate whey proteins. We examined the effects of AOT (sodium bis(2-ethylhexyl) sulfosuccinate) concentration and pH on the precipitation rates of α-LA and β-LG. At an AOT concentration of 0.004 M or higher, both proteins exhibited 100% precipitation within the pH range of 4.0–5.5, whereas at 0.002 M, the precipitation rate was reduced. Additionally, when the pH exceeded the isoelectric points of α-LA (pH 4.4) and β-LG (pH 5.1), the precipitation rate sharply declined. This result suggests that the negative surface charge of proteins at higher pH levels prevents their interaction with the negatively charged AOT. However, no significant difference in precipitation behavior was observed between α-LA and β-LG despite their slight isoelectric point differences. Furthermore, precipitation rates decreased below pH 4.5, though the underlying cause remains unclear. These findings provide fundamental insights for the selective separation of milk whey proteins, paving the way for optimizing conditions to develop cost-effective and practical separation technologies.

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In this study, we focused on the molecular chirality of poly L-amino acids, and aimed to improve the chemical immobilization rate of poly L-amino acids on the surface of silica gel particles, with the aim of applying them to the packing material of HPLC columns for the optical resolution of racemic compounds. In previous research, the immobilization rate of PLTRP synthesized using commercially available silica gel initiators was around 7%. In this research, however, the immobilization rate was improved to around 26%. This is thought to be because more PLTRP was able to be immobilized on the silica gel surface, as the weight loss of the commercially available initiators by TG-DTA was around 0.3%, whereas that of the material synthesized in this research was 3.0%.

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【Machine Translation】 In this study, organic–inorganic composite thin films composed of gold nanoparticles and a hydrophobic polymer were fabricated to investigate the formation of micro-periodic structures and the appearance of structural color. Gold nanoparticles were synthesized using chloroauric acid as a precursor and dispersed in toluene to prepare nanoparticle inks. Ethyl cellulose was used as a hydrophobic polymer to prepare gold nanoparticle/polymer composite inks with controlled mass ratios. The composite inks were dropped onto the water surface and subsequently transferred onto hydrophobically treated glass substrates to form thin films. Scanning electron microscopy (SEM) observations revealed that the dispersion and aggregation states of gold nanoparticles varied depending on the mass ratio of nanoparticles to polymer. Optical characterization showed that samples with high gold nanoparticle content exhibited coloration originating from localized surface plasmon resonance (LSPR), whereas a blue structural color was observed near a specific composition. These results suggest that controlling the mass ratio of gold nanoparticles and polymer enables tuning of nanoparticle aggregation structures and the resulting optical properties.

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【Machine Translation】 Metal–hydroxide species (M–OH) play important roles as active intermediates in enzymes that catalyze the hydrolysis of esters and peptides, and model complexes have been widely studied to understand their reaction mechanisms. In this study, a dinuclear cobalt(II,II) (μ-hydroxido)(μ-pyrazolato) complex supported by a hydrotris(3,5-diisopropyl-1-pyrazolyl)borate ligand was synthesized through a new synthetic route, and its reactivity was investigated. The obtained complex was stable toward molecular oxygen in toluene solution. In contrast, when reacted with p-nitrophenyl acetate, the bridging hydroxide ligand acted as a nucleophile and attacked the carbonyl carbon of the ester, leading to cleavage of the ester C–O bond. The reaction produced a mononuclear cobalt(II) p-nitrophenoxide complex and related species, and the structure of the product was determined by X-ray crystallographic analysis. Kinetic analysis using electronic absorption spectroscopy revealed a pseudo-first-order rate constant of 1.72 × 10⁻³ s⁻¹ at 297 K.

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【Machine Translation】 In this study, we synthesized copolymers of BLG and L-Tryptophan (LTRP) and evaluated their membrane properties, with the aim of investigating the effect of differences in the combination of amino acids on membrane properties. It was found that the homopolymer of poly L-tryptophan is insoluble in dichloromethane, the solvent used in film formation. Therefore, when a copolymer was synthesized with γ-BLG-NCA, it was found that the composition ratio of LTRP:BLG=1:1 was insoluble in dichloromethane, but that it dissolved in dichloromethane when the ratio was 1:2. We believe that the reason for the larger contact angle compared to PBLG is due to the influence of the hydrophobicity of L-Tryptophan. In addition, the reason for the increase in tensile strength is thought to be due to the aromatic rings of L-Tryptophan stacking due to π-π interactions, and the strong intermolecular forces.

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【Machine Translation】 In this study, we used L-tryptophan (LTRP) as a raw material, immobilized poly-L-tryptophan (PLTRP) on silica gel particles, and packed the particles into an HPLC column to evaluate the optical resolution of various racemates. In this study, we optimized the polymerization conditions and increased the immobilization rate of PLTRP from around 7% in previous studies to around 16%. We believe that this is what led to the observed resolution. In the future, we aim to achieve complete separation by increasing the theoretical plate number of the column.

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【Machine Translation】 An aqueous two-phase system (ATPS) composed of a deep eutectic solvent (DES) prepared from choline chloride and urea at a 1:2 molar ratio and an aqueous salt solution was constructed, and the partitioning behavior and secondary structural changes of lysozyme were investigated. Among the salts examined, two-phase formation was observed exclusively with K₂HPO₄ at concentrations of 0.5–0.6 g/mL, suggesting that a salt with a strong salting-out effect is required due to the high hygroscopicity of the DES. The extraction efficiency of lysozyme exceeded 93% under all salt concentration conditions tested, and the partition coefficient increased with increasing salt concentration. This behavior is attributed to the preferential transfer of lysozyme into the DES-rich upper phase driven by the salting-out effect. Circular dichroism (CD) spectroscopy revealed a red shift in the negative peak with increasing DES concentration, indicating that the DES induces changes in the secondary structure of lysozyme. Since the DES is a mixture of a hydrogen bond acceptor and a hydrogen bond donor, it is inferred that hydrogen bonding is responsible for both the driving force of extraction and the observed conformational changes.

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【Machine Translation】 Ishizuchi Kurocha, a post-fermented tea produced in Saijo City, Ehime Prefecture, was subjected to decaffeination using supercritical carbon dioxide, and the effects of water hardness on the physicochemical properties and antioxidant activity of the tea extract were investigated. Extraction with hard water yielded a darker and more turbid infusion compared to soft water, with pH values of 6.5 and 4.0, respectively. The predominant organic acid in the extract was lactic acid at a concentration of approximately 4 mmol/L regardless of water hardness. The increase in pH with hard water was attributed to neutralization of lactic acid by Mg²⁺ and Ca²⁺ ions. The caffeine content of Ishizuchi Kurocha was 1.49%, and the caffeine removal efficiency achieved by supercritical CO₂ treatment was 91.7%. After decaffeination, the pH and color of the extracts remained largely unchanged from untreated samples, suggesting that organic acids such as lactic acid were not substantially removed by the treatment. Antioxidant activity assessed by the ORAC method was maintained regardless of decaffeination and water hardness, indicating that caffeine does not contribute to the antioxidant capacity of Ishizuchi Kurocha

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【Machine Translation】 In this study, we attempted to develop a method to easily analyze sunscreens by employing a UV-visible spectrophotometer, which is used to evaluate optical properties. UV-protective ingredients in sunscreens include UV absorbers and UV scatterers. The former function by light absorption and thermal deactivation through the π-conjugated system in organic compounds, while the latter function by scattering light through metal oxide microparticles. Either one or both of these two types are used in sunscreens, which come in a variety of formulations such as gels and powders. This report describes the results of analysis of a wide variety of commercially available products. The spectrum of sunscreen gel A, which contains both UV absorbers and scatterers, showed a broad absorption band in the UV region in the undiluted state, but its absorption maximum could not be confirmed (Figure 1). This was expected because the concentration of the UV-protecting component in the gel was extremely high, and the amount of reflected light obtained under the relative diffuse reflectance method was small, making it impossible to compare absorbance at different wavelengths. Therefore, we conducted the measurement again under the condition that the sunscreen was dispersed 100 times by mixing Gel-A and PTFE powder with high reflectance in the ratio of 1:99 (Figure-2). In contrast to the spectrum of the original solution, absorption maxima were observed at 350 nm and 313 nm. It was also found that by increasing the number of integrations, a smooth spectrum with little noise could be obtained. In the presentation, we will report the results of measurements of other dosage forms such as cream, powder, and solid stick.

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【Machine Translation】 In this study, we investigated the synthesis of surface-modified CNF aggregate with excellent affinity to lacquer solution with the aim of developing a nanocomposite dry lacquer material using CNF as an aggregate. Specifically, CNF hydrogel, a candidate aggregate, was prepared by modifying the acidified TEMPO-oxidized CNF surface with polydopamine containing catechol groups and cross-linking it with an amine-based cross-linking reagent (gelatin). By cross-linking reaction with gelatin, CNF hydrogels were synthesized for use as aggregate in nanocomposite dry lacquer materials.

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【Machine Translation】 In this study, we investigated the interaction of an amphiphilic molecule N-(10-carboxydecyl)-N-(3-carboxypropyl)-N,N-dimethylammonium bromide (1), which has two carboxy groups at different distances from the hydrophilic group, with an amidine derivative with a long alkyl chain, 4-octyloxyphenylamidine (2). (2) in water. Compound 1 was obtained by a three-step organic synthesis, while compound 2 was synthesized by Williamson synthesis and amidino group conversion of cyano groups. 13C NMR measurements in heavy water suggested that the carboxy group near the hydrophilic group interacted with the amidine. Furthermore, temperature-variable 1H NMR measurements confirmed that the aromatic proton of compound 2 shifts to a lower magnetic field with increasing temperature and that the interacting carboxy group switches. This indicates that amidine preferentially interacts with carboxy groups away from the interface of the molecular assembly as the temperature rises. The results of this study may contribute to the design of temperature-responsive molecular assemblies.

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【Machine Translation】 In this study, we measured the concentration dependence of freezing point depression and specific viscosity of aqueous solutions of organic compounds with different carbon and hydroxyl group numbers, and investigated the relationship between them. Ethanol, propylene glycol, and glycerin were used as solutes, and their non-ideal behavior in aqueous solutions was investigated. As a result, the freezing point depression and specific viscosity of each solution deviated from the ideal solution at concentrations above a certain level, confirming the non-ideal behavior due to cluster formation. Furthermore, an extremely high correlation was observed between freezing point depression and specific viscosity, and the coefficient of determination was higher than 0.9965. This suggests that the formation of clusters has a similar effect on both properties. The relationship between the two properties differed depending on the type of solute, indicating that the number of carbons, number of hydroxyl groups, molecular weight, dipole moment, and hydration energy of the solute are possible influencing factors. The results of this study may provide guidelines for understanding the properties of non-ideal solutions and for controlling their physical properties.

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【Machine Translation】 The objective of this study was to construct a circulating flow hydrogen production system combining platinum-supported titanium dioxide (Pt/TiO₂ ) catalysts and symbiotic algae. Conventional hydrogen production using TiO₂ catalysts has been hampered by the need for sacrificial reagents, CO₂ byproduction, and the difficulty of continuous operation. In this study, we attempted to develop a sustainable hydrogen production system without CO₂ emissions by using sugars (maltose, glucose, etc.) produced by symbiotic algae through photosynthesis as sacrificial reagents. First, a microflow reactor (MCR) incorporating Pt/TiO₂ thin films was fabricated, and the optimal reaction conditions (flow rate, channel size, etc.) for hydrogen generation were evaluated. Next, sugar secretion by symbiotic algae was measured in sample bottles and flow reactors to investigate sugar production under light irradiation conditions. Furthermore, a flow reactor in which symbiotic algae were settled was connected to a Pt/TiO₂ thin film-embedded MCR, and continuous operation of hydrogen production was conducted. As a result, continuous generation of hydrogen gas was confirmed by using the sugar produced by the symbiotic algae. The results of this research will contribute to the development of hydrogen production technology with low environmental impact using renewable energy, and may serve as a fundamental technology for the realization of a sustainable energy society.

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In this study, we synthesized γ-Buthyl-L-Glutamate (γ-BuLG) NCA and γ-Fluorobenzyl-L-Glutamate (γ-FBLG) NCA for the synthesis and polymerization of novel L-amino acid glutamate derivatives. Poly L-amino acids have excellent biodegradability and biocompatibility, and are expected to be applied as environmentally adaptive materials. However, there have been few studies on poly L-glutamates with protective groups other than benzyl or methyl groups introduced into the carboxy group at the γ-position. In this study, 1-butanol and 4-fluorobenzyl alcohol were used as new protecting groups, and synthesis and polymerization of the respective NCAs were attempted. The yield of the synthesized γ-BuLG-NCA was 2.15%, and the obtained poly γ-BuLG had extremely low solubility, making it difficult to evaluate its physical properties. On the other hand, the yield of γ-FBLG-NCA was 27.8%, and a broad signal was observed in ¹H-NMR of Poly γ-FBLG after polymerization, confirming polymer formation. In the future, we will optimize the polymerization conditions and evaluate the physical properties to clarify the functionality of the new poly L-glutamate.

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Microfluidic paper-based analytical devices (µPADs) have significant potential for applications in environmental analysis and medical diagnostics. µPADs utilize colorimetric reactions between analytes and reagents, enabling simple and cost-effective analysis. They are particularly useful in developing regions where laboratory facilities and financial resources are limited. However, conventional µPADs are typically fabricated using wax printers, which are no longer in production, necessitating the development of alternative methods for creating flow channels. This study proposes a novel method using spray-coated rosin, a natural resin, to form µPAD flow channels and evaluates its characteristics. In this study, masking was applied to filter paper, followed by spraying rosin solution to create the flow channels. Parameters such as spray distance, the number of sprays, and the solvent for rosin were varied to determine optimal conditions. The acid and base resistance of the fabricated µPADs was evaluated by introducing acidic and basic solutions into the channels and assessing their structural integrity. Additionally, neutralization titration was conducted and compared with conventionally fabricated µPADs. The results indicated that the optimal conditions for flow channel formation involved spraying rosin-ethanol solution five times on both sides of the paper from a distance of 7 cm. The channels remained intact with 1 mol/L HCl solution but were disrupted by 1 mol/L NaOH solution. When NaOH solution was diluted, channel integrity was maintained at concentrations of 0.01 mol/L (pH 9) or lower. Neutralization titration results showed that all detection zones exhibited color changes in rosin-based µPADs, whereas conventionally fabricated µPADs displayed color changes in a limited range. This study demonstrates that spray-coating with rosin is a viable method for forming µPAD flow channels. Future research will focus on improving channel durability and evaluating compatibility with various reagents to develop more practical µPADs.

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In Japan, large quantities of eggshell waste are generated due to high egg consumption. Although some eggshells are reused as chalk or fertilizer, most are discarded without recycling. Eggshells are primarily composed of calcium carbonate and possess a porous structure and membrane with excellent adsorption properties, making them a promising material for environmental applications. This study aims to evaluate the odor adsorption performance of gypsum boards containing eggshell powder, focusing on common indoor air pollutants: ammonia, acetic acid, and formaldehyde. Eggshells were washed, dried, and ground into powders with particle sizes of 250 μm and 850 μm. The powders were mixed with hemihydrate gypsum at 5–20% ratios, poured into molds, and cured to form gypsum boards. Adsorption tests were conducted by placing cut gypsum board samples in glass desiccators with the odorants and measuring concentration changes every 30 minutes. The results showed that all compositions of eggshell-added gypsum boards were successfully formed. Notably, boards containing eggshell powder exhibited significant ammonia adsorption, while pure gypsum boards showed negligible adsorption. Boards with 20% eggshell addition maintained ammonia adsorption for up to 3 hours. This suggests that proteins in the eggshell membrane contribute to ammonia adsorption. Adsorption behavior for acetic acid and formaldehyde, as well as the effect of particle size and content, will be presented in detail at the conference. This study demonstrates the potential of waste eggshells as a functional material for improving indoor air quality, contributing to the development of sustainable building materials and aligning with SDGs initiatives.

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Ammonia, widely used in industrial and agricultural processes, is also a significant environmental pollutant due to its contribution to water contamination and malodor when released into the environment. In developing countries, there is a particular need for low-cost and easy-to-use methods for ammonia detection, given the lack of infrastructure and personnel for water quality monitoring. This study aims to develop a simple detection method for ammonia using a paper-based microfluidic analytical device (μPAD) based on the indophenol method. The device was fabricated by printing hydrophobic ink on hydrophilic paper using a Xerox ColorQube 8580N printer, forming circular flow channels designed in Microsoft PowerPoint. The detection protocol involved sequentially adding four reagents, followed by the ammonia-containing sample to initiate the colorimetric reaction. After the color reaction, the device was scanned using a Canon Canoscan LiDE400, and image analysis was conducted using various color models (RGB, HSV, Lab*, LCh, ΔE). Ammonium chloride solutions ranging from 0 to 0.1 M were tested, and a strong correlation (R² ≈ 0.95) was observed between the c* (chroma) value and ammonia concentration within 10 minutes of the reaction. Although linearity decreased over time, the results confirmed the potential for rapid quantification. This method enables affordable and rapid ammonia detection without the need for expensive instruments or specialized techniques, and it holds promise for practical applications in water quality monitoring. Future work will focus on improving color intensity and reproducibility, as well as expanding the approach to other analytes.

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Layered double hydroxides (LDHs) possess a structure in which water molecules and exchangeable anions are intercalated between positively charged metal hydroxide layers, making them promising materials for environmental remediation due to their high anion-exchange capacity. However, their powdered form limits practical applications, and solidification is essential for broader usage. Electrospinning (ES) is a method for fabricating polymer nanofibers under high voltage and enables composite formation with various inorganic materials. In this study, LDH was incorporated into polymethyl methacrylate (PMMA) using a THF-DMF mixed solvent to fabricate composite membranes via ES. Previous studies reported that LDH dissolved in CHCl₃-DMAc solvents; thus, solvent modification was aimed at achieving successful LDH incorporation. Electrospinning was conducted under conditions of 1.0 mL/hr feed rate, 25 kV applied voltage, and 150 mm needle-to-collector distance. The resulting membranes were evaluated using SEM and FT-IR. FT-IR spectra confirmed characteristic PMMA peaks, while SEM images showed bead-like polymer deposits rather than typical fibrous structures, likely due to changes in viscosity and flow behavior caused by the solvent. This study provided foundational insights for optimizing LDH composite formation via electrospinning.

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Ultraviolet (UV) radiation is known to cause adverse effects on human health, and sunscreen is commonly used for protection. In this study, we evaluated a simple and visual method to assess the effectiveness of sunscreens using UV-sensitive beads. These beads contain photochromic compounds that change color upon UV exposure. Four commercial sunscreen products (A–D) with SPF50+ and PA++++ ratings were applied to the beads, which were then exposed to sunlight under controlled conditions. The color change was quantified through RGB image analysis, with the green (G) value used as an indicator—higher G values corresponded to greater UV protection. Additionally, the UV absorption spectra of diluted solutions of the sunscreens were measured using UV–Vis spectroscopy to assess correlation with the bead-based results. The experiment revealed noticeable differences in bead coloration among the products, suggesting the method's potential for visualizing relative UV protection. However, discrepancies between the G values and UV absorption characteristics indicated limitations in quantitative accuracy. Despite this, the UV-sensitive bead approach offers a simple, non-invasive means of comparing sunscreen effectiveness and can serve as an effective educational tool.

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The taste of beverages may be influenced by the materials they come into contact with, such as containers and stirring tools. In this study, we investigated the impact of various materials on the flavor of commercially available café latte and sake through sensory evaluation. Stirring implements included binchōtan charcoal (known for deodorizing and impurity-absorbing effects), Bizen ware (traditionally used for sake vessels), a stainless-steel medicine spoon, and a commercially sold “magic stirrer.” Each beverage was stirred for 10 seconds under standardized conditions, and untreated samples served as the control. A panel of fifteen individuals in their twenties evaluated the samples on six attributes: aroma, flavor intensity, sweetness, sourness, ease of drinking, and mouthfeel, using a five-point scale. Results showed minimal change for café latte, with scores remaining close to the untreated baseline. In contrast, sake exhibited notable improvements in most categories, particularly with binchōtan enhancing ease of drinking and the stainless spoon improving flavor intensity. These findings suggest that in addition to possible chemical interactions, factors such as aeration and mechanical mixing during stirring may influence taste. The effects varied depending on the type of beverage and its constituent components.

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Alpha rice, a precooked and dried rice product, can be easily rehydrated with water or hot water to regain a freshly cooked texture. While widely used as emergency food due to its long shelf life, its taste is generally inferior to that of freshly cooked rice. This study aimed to improve the eating quality of alpha rice by investigating the effects of cold soaking (at -1.0 °C) on rice before cooking. Koshihikari rice harvested in Tottori Prefecture in 2023 was soaked for 6–24 hours under cold or room temperature conditions, then cooked and dried using a forced convection dryer at 80 °C for 3 hours to produce alpha rice. The rehydrated alpha rice, obtained by adding hot water and steaming for 15 minutes, was evaluated for color and gloss, sweetness, softness, stickiness, and aroma by sensory tests. The results showed that alpha rice prepared from room-temperature-soaked rice received higher scores for sweetness, softness, and stickiness. In contrast, the cold-soaked samples exhibited insufficient water absorption at the rice core, resulting in incomplete rehydration. This was likely due to excessive gelatinization of the surface layer during cold treatment, which inhibited water penetration. These findings suggest that optimizing rehydration conditions, such as heating method and time, is essential to improve the quality of cold-soaked alpha rice.

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In Lake Nakaumi, large-scale dredging associated with land reclamation projects created approximately 8 km² of dredged depressions. These depressions, with poor water circulation, have led to hypoxic conditions and accumulation of high concentrations of nutrients and hydrogen sulfide. Traditional backfilling materials such as marine sand and dredged soil face issues of supply limitations and organic matter resuspension. In this study, coal ash granules solidified with cement—produced as a by-product of thermal power plants—were used to backfill dredged depressions in stages from 2019 to 2022. The effectiveness and persistence of nutrient and hydrogen sulfide suppression were evaluated through field investigations conducted between 2021 and 2024. Measurements of water temperature, salinity, dissolved oxygen, and nutrient concentrations (NH₄⁺-N and PO₄³⁻-P) in bottom water layers were carried out at both backfilled and unfilled sites. Results indicated that maximum concentrations at a previously high-nutrient site declined from 2.70 mg/L (NH₄⁺-N) and 1.89 mg/L (PO₄³⁻-P) in 2022 to 0.39 and 0.24 mg/L, respectively, by 2024. These findings demonstrate that coal ash granule backfilling can significantly suppress nutrient release from sediments for at least two years after backfilling.

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Tsubasa Pond, located within Yonago Waterbird Sanctuary, is a brackish artificial wetland created from reclaimed land in Lake Nakaumi and is known as a vital habitat for wild birds. However, environmental degradation has been observed due to algal blooms, hydrogen sulfide generation, and sediment accumulation caused by bird excrement and other factors. This study evaluated two techniques aimed at improving water quality by reducing nutrient concentrations (total nitrogen and total phosphorus). The first method involved sprinkling pond water onto the shoreline soil where emergent vegetation such as reeds grows, facilitating nutrient removal through plant uptake and microbial activity. The second method introduced submersible fine bubble generators to promote oxygen supply and enhance organic matter decomposition in sediments. Field tests conducted from April to September 2024 revealed that the sprinkling bed system removed 6.27 kg of total nitrogen and 0.96 kg of total phosphorus, effectively reducing nutrient levels. Additionally, measurements near the fine bubble devices showed elevated oxidation-reduction potential (ORP) and increased abundance and diversity of benthic organisms, indicating improved sediment conditions. These results suggest that the combined application of the sprinkling bed and fine bubble techniques is effective for water purification in urban wetlands.

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In Lake Nakaumi, external inflow accounts for approximately 80% of the total pollution load. Among inflowing rivers, Kamo River and Shin-Kamo River significantly affect the water quality in Yonago Bay. This study investigated the relationship between river discharge (Q) and pollutant load (L) to clarify the pollution characteristics of these rivers. Field surveys were conducted under fair weather conditions at two downstream sites: Tenjin Bridge (Kamo River) and Nishiotani Bridge (Shin-Kamo River). Basic water quality parameters (e.g., temperature, salinity, pH, DO, ORP), COD, total nitrogen, and total phosphorus were measured, and load was calculated by multiplying concentrations by flow rates. From the obtained L-Q relationships (L = aQ), the slope “a” indicated that COD loads in Shin-Kamo River increased more steeply with flow, suggesting a strong influence from non-point agricultural sources. In contrast, Kamo River, which receives water from the environmentally compliant Hino River and flows through the urban center, showed more stable water quality. These findings suggest that reducing agrochemical usage and improving paddy field water management in the Shin-Kamo River basin could effectively improve water quality in Yonago Bay.

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Chitosan, a biodegradable basic polysaccharide, has drawn attention as an environmentally friendly material. This study aimed to investigate its potential to attract aquatic organisms in brackish water environments. Four types of traps were prepared: (a) solid chitosan, (b) wood chips treated with chitosan acetate and fixed using ammonia water, (c) wood chips sprayed with ammonia water only, and (d) untreated wood chips. These were submerged in the drainage channel of reclaimed land in Lake Nakaumi for 6–9 days from late November to early December. Captured species and their numbers were recorded and compared. An additional indoor experiment assessed microbial proliferation in environmental water with and without solid chitosan under natural light at approximately 24°C. The results showed that traps containing chitosan captured significantly more organisms than the untreated controls, suggesting a biological attraction effect. Solid chitosan appeared to attract Palaemonidae, whereas chitosan acetate was more associated with attracting Gobiidae. These findings suggest that the form of chitosan may influence selective attraction of marine organisms.

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Drying hair is a daily activity that significantly affects hair health and appearance. This study examined four hair drying methods—natural drying, hot air drying, hot + cold air drying, and partial drying—to determine which best maintains hair beauty. Hair samples from an 11-year-old girl with no history of dyeing or perming were washed using identical shampoo and conditioner, then dried using each method. Post-drying evaluations included a survey on visual and tactile impressions, SEM observation of cuticles, and TG-DTA analysis for moisture content. The survey indicated that hot + cold air drying was most preferred, followed by natural drying. SEM images revealed cuticle damage even in natural drying, with more pronounced damage in samples subjected to combined hot and cold air. Although cold air may temporarily close cuticles due to temperature differences, prolonged heat exposure may cause structural damage. This study offers scientific insights into how common hair drying practices influence hair quality, aiming to support better hair care habits.

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On the Yumigahama Peninsula in western Tottori Prefecture, biting damage caused by Culicoides tokunagai and Culicoides iso has become a significant concern. In recent years, the expansion of abandoned farmland has led to an increase in larval habitats, raising concerns about growing damage to residents. This study examined the effectiveness of mowing and dolomite lime application as control measures against dipteran larval emergence in abandoned farmland. Three sites were established in Hikona-cho, Yonago City: an untreated control site (HO), a single-treatment site (HA), and a double-treatment site (HB). Soil samples were collected weekly from April to October to monitor larval populations. The results showed that larval counts decreased at treated sites, with a particularly marked reduction at site HB, where mowing was conducted twice. A Mann-Whitney U test confirmed a statistically significant difference between the untreated site and the double-treatment site. Multiple mowing sessions raised ground temperatures to as high as 50°C, which is believed to have created an inhospitable environment for biting midges, thereby contributing to the observed reduction in larval numbers.

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Biting damage caused by Culicoides tokunaga and Culicoides iso has been reported on the Yumigahama Peninsula; however, no survey of their habitat had previously been conducted in Sakaiminato City, which is adjacent to Yonago City. In this study, adult biting midge collections were carried out at six sites in Sakaiminato City and one site in Yonago City from late April to late July to compare the occurrence patterns between the two cities. The results revealed that C. tokunagai was present at all six sites in Sakaiminato, confirming its widespread distribution throughout the city. C. iso was also collected across a broad range of sites in Sakaiminato, with a higher frequency of occurrence compared to Yonago City. Differences in species composition, abundance, and seasonal occurrence were observed between the two cities, suggesting that environmental factors such as ground temperature and soil conditions may play a contributing role.

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Biting midges of the family Ceratopogonidae, including species with hematophagous females, are known to cause biting damage on the Yumigahama Peninsula in western Tottori Prefecture, particularly between May and July. While two main species—Forcipomyia tokunagai and Dasyhelea sp.—have been identified in the region, ecological data on the latter are limited, and some areas such as coastal windbreak forests remain uninvestigated. In this study, we surveyed the larval habitats of dipteran insects, primarily F. tokunagai, in four sites within the windbreak forests, sampling soils from sunlit and shaded areas and counting larvae using a saturated salt water separation method. A peak in larval numbers was observed from May to June, with a general decline as ground temperatures increased, although exceptions were noted. Larvae tended to be more abundant in shaded areas, though no clear correlation with soil temperature was found. For Dasyhelea larvae, only one of the three surveyed sites (SW) in Sakaiminato City confirmed their presence, likely due to its brackish water conditions. This study provides valuable data for understanding midge distribution and developing control strategies.

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Nitrite ions in environmental water are unstable and must be analyzed promptly after sampling. This study aimed to develop a simple and rapid detection method for nitrite ions using a layered microfluidic paper-based analytical device (μPAD). The flow channels were designed using PowerPoint and patterned with hydrophobic wax onto hydrophilic paper using a wax printer. A multi-layer structure (7–10 layers) was constructed, and nitrite ions were detected via the Griess reaction, which induces color development. Investigation of the effect of the number of layers revealed that standard deviation increased with more layers, indicating that a 7-layer configuration was optimal. To enhance sensitivity for nitrate ions, an acetic acid solution containing magnesium chloride and sodium chloride was added to the μPAD. While nitrite solutions showed increased color intensity, nitrate solutions did not exhibit a significant change, suggesting that further optimization is necessary. This study demonstrates the potential of μPADs as convenient tools for on-site environmental monitoring.

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Boron is widely used in semiconductors, glass, and pesticides, yet it poses ecological risks due to its toxicity to plants and insects. To enable rapid and on-site boron detection, this study developed and evaluated a novel sensing material by incorporating chromotropic acid (CTA), a fluorescent reagent, into layered double hydroxides (LDH). First, a carbonate-type Mg-Al LDH was converted into an acetate form, followed by the introduction of CTA and the surfactant C4S to synthesize CTA/LDH and CTA/C4S/LDH composites. X-ray diffraction (XRD) revealed changes in interlayer spacing with increasing CTA content, while FT-IR spectroscopy indicated structural variations. Fluorescence measurements showed that the CTA(0.1% AEC)/LDH composite exhibited the strongest fluorescence, with emission intensity proportional to boron concentration under pH 6.0, demonstrating good quantitativeness. At higher CTA concentrations, fluorescence quenching occurred due to molecular aggregation. Although C4S improved interlayer spacing, it appeared to hinder boron interaction. These results suggest that the CTA(0.1%)/LDH composite is a promising material for simple and sensitive detection of dissolved boron in environmental samples.

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