Publications by authors named "Chihiro Yoshimura"

Eutrophication countermeasures have been implemented in various reservoirs across Japan to mitigate phytoplankton blooms. However, the responses of phytoplankton to these countermeasures are not yet fully understood. This study aimed to investigate the impact of in-reservoir eutrophication measures on phytoplankton productivity using relevant datasets covering 55 reservoirs in Japan from 1993 to 2017.

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Intimately coupled photocatalytic biodegradation (ICPB) has been recently developed as an efficient wastewater treatment technique, particularly for removing persistent organic pollutants. However, photocatalyst/biofilm interaction in terms of photoelectron transfer and its effect on the overall performance of ICPB has not been explored. To investigate these points, interface-engineered composites of bismuth vanadate and reduced graphene oxide with low degree (BiVO/rGO-LC) and high degree of their contact (BiVO/rGO-HC) were fabricated and applied for ICPB.

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Pindolol (PIN) is a commonly used β-blocker drug and has been frequently detected in various natural waters. Comprehensive understanding of its environmental photochemical transformation is necessary to assess its environmental risk. In this study, the photodegradation kinetics and mechanisms of PIN in both freshwater and coastal water were investigated for the first time.

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The excited triplet-state of dissolved organic matter (DOM*) is a major reactive intermediate in sunlit waters. Its quantum yield is important in understanding the fate of organic micropollutants. The degradation efficiency of its chemical probe, 2,4,6-trimeythlphenol (f), is generally used as a proxy of the quantum yield.

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This article proposes a method for an artificial agent to behave in a social manner. Although defining proper social behavior is difficult because it differs from situation to situation, the agent following the proposed method adaptively behaves appropriately in each situation by empathizing with the surrounding others. The proposed method is achieved by incorporating empathy into active inference.

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Direct and indirect photolysis are important abiotic processes in aquatic environments through which plastics can be transformed physically and chemically. Transport of biodegradable plastics in water is influenced by vertical mixing and turbulent flow, which make biodegradable plastics remain susceptible to sunlight and photolysis despite their high density. In general, biodegradable plastics are composed of ester containing polymers (e.

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Introduction: In recent years, the widespread shift from on-site to remote work has led to a decline in employees' mental health. Consequently, this transition to remote work poses several challenges for both employees and employers. To address these challenges, there is an urgent need for techniques to detect declining mental health in employees' daily lives.

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Man-made reservoirs are important for human daily lives and offer different functions, however they are contaminated due to anthropogenic activities. Dissolved organic matter (DOM) from each reservoir is unique in composition, which further determines its photo-reactivity. Thus, this study aimed to investigate the photo-reactivity of reservoir DOM in terms of the quantum yield for photo-production of singlet oxygen (Ф).

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Monitoring bacteria is essential for ensuring microbial safety of water sources, including river water and treated wastewater. The plate count method is common for monitoring bacterial abundance, although it cannot detect all live bacteria such as viable but non-culturable bacteria, causing underestimation of microbial risks. Live/Dead BacLight kit, involving fluorochromes SYTO 9 and propidium iodide (PI), provides an alternative to assess bacterial viability using flow cytometry or microscopy.

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Photochemical reactions widely occur in the aquatic environment and play fundamental roles in aquatic ecosystems. In particular, solar-induced photodegradation is efficient for many organic micropollutants (OMPs), especially those that cannot undergo hydrolysis or biodegradation, and thus can mitigate chemical pollution. Recent reports indicate that photodegradation may play a more important role than biodegradation in many OMP transformations in the aquatic environment.

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Dissolved silicon (DSi) is essential for aquatic primary production and its limitation relative to nitrogen (N) and phosphorus (P) facilitates cyanobacterial dominance. However, the effects of DSi on phytoplankton growth and community structure have yet to be fully determined in tropical lakes, particularly in relation to N and P. Therefore, this study investigated the role of DSi in Tonlé Sap Lake, Cambodia, a tropical floodplain system well known for its flood-pulse characteristics and high productivity.

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Surface code is a promising candidate for the quantum error corrections needed for fault-tolerant quantum computations because it can operate on a two-dimensional grid of qubits. However, the gates and control lines become dense as more and more qubits are integrated, making their design and control difficult. This problem can be alleviated if the surface code can operate on sparse qubit arrays.

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Sewage comprises multifarious information on sewershed characteristics. For instance, influent sewage quality parameters (ISQPs) (e.g.

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Bacterial regrowth after water/wastewater disinfection poses severe risks to public health. However, regrowth studies under realistic water conditions that might critically affect bacterial regrowth are scarce. This study aimed to assess for the first time the regrowth of () in terms of its viability and culturability in environmental waters after chlorine disinfection, which is the most widely used disinfection method.

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Antihypertensive propranolol (PRO) is frequently detected in surface waters and has adverse effects on aquatic organisms. In this study, its photochemical fate in surface water with the aspect of kinetics, products and toxicity were investigated employing steady-state photochemistry experiments and ecotoxicity tests. The results showed that photodegradation of PRO was enhanced in river water than that in phosphate buffer where dissolved organic matter (DOM), NO, and HCO played important roles.

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Despite there being numerous models of trihalomethane (THM) formation, they are limited by high estimation errors, which can be close to the regulatory limits for THMs, due to the fluorescence quenching effect. In this research, the estimation error for THM formation was reduced by correcting the quenching effect. The trihalomethane formation potential (THMFP) test was conducted in the presence of chlorine and bromine, individually and in mixtures.

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Acebutolol (ACE) has been widely used for the treatment of cardiovascular disorders, and its photochemical fate in natural waters is a matter of concern due to its ubiquitous occurrence and its toxicity to aquatic organisms. In this study, the photodegradation of ACE in river water and synthetic waters were investigated under simulated sunlight irradiation. The results demonstrated that ACE photodegradation rate in river water was 3.

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Phytoremediation of eight metals in mangrove forests was investigated by focusing on Avicennia marina at three locations along the Egyptian Red Sea coast. Average concentrations of metals in sediment followed the sequence Fe > Mn > Zn > Pb > Cr > Cu > Ni, while Cd was below the detection limit. Metal pollution index and enrichment factor indicated contamination of sediment by Pb, Cu, and Mn.

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Regrowth of bacteria after water/wastewater disinfection is a serious risk to public health, particularly when such pathogens carry antibiotic resistance genes. Despite increasing interest in light-based disinfection using ultraviolet or solar radiation, the mechanism of bacterial regrowth and their concentration upon light exposure (i.e.

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Natural organic matter (NOM) can inhibit the photocatalytic degradation of organic micropollutants (OMPs) through inner filter effect, reactive oxygen species (ROS) scavenging, and competitive adsorption. However, previous studies have focused solely on the bulk properties of NOM and our understanding of the inhibition mechanism by NOM fractions during photocatalytic degradation of OMP is still fragmentary. In this study, five well-characterized different NOM samples (i.

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Magnetic carbon nanotube (MCNT) composites with titanium dioxide (TiO) have an enhanced photocatalytic disinfection efficiency (i.e. higher disinfection rate) and better applicability (i.

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Recently, a series of new photocatalysts have been developed for to combat diverse bio-recalcitrant contaminants and the inactivation of bacteria. Modeling photocatalytic processes is important to assess these materials, and to understand and optimize their performance. In this study, the recent literature is critically reviewed and analyzed to identify and compare methods of modeling photocatalytic performance.

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2-Methylisobornel (MIB) is one of the most widespread and problematic biogenic compounds causing taste-and-odor problems in freshwater. To investigate the causes of MIB production and develop models to predict the MIB concentration, we have applied empirical dynamic modeling (EDM), a nonlinear approach based on Chaos theory, to the long-term water quality dataset of Kamafusa Reservoir in Japan. The study revealed the dynamic nature of MIB production in the reservoir, and determined causal variables for MIB production, including water temperature, pH, transparency, light intensity, and Green Phormidium.

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During runoff process, the urban road dust (URD) passes through the road-side gutters and detention tanks, where it gets hold for a certain period of time, hours to weeks, before making its way into the water bodies. A part of the water-exchangeable toxicants are leached by the water, and some strongly bound toxicants remain attached to the URD. Toxicity of urban runoff is dependent on holding time, water volume, and the type and composition of the wet road dust (WeRD) and leachate.

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Article Synopsis
  • River ecosystems play a crucial role in processing terrestrial organic carbon, and this process is heavily influenced by microbial activity.
  • A global study involving over 1000 river and riparian sites revealed distinct carbon processing patterns across different biomes, showing slower processing at higher latitudes and faster rates near the equator.
  • The findings suggest temperature and environmental factors affect carbon processing rates, providing a foundation for future biomonitoring efforts to assess environmental impacts on ecosystems worldwide.
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