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Asst. Prof. Yuki NAKAYA (Dr. Sc.)

Faculty of Engineering, Hokkaido University

Research Interest

Application of solid-phase fluorescence excitation emission matrix (SPF-EEM) spectroscopy to environmental samples

• Analysis of soil and humic substances (A-5, A-20, OP-1, OP-2, OP-4, PP-8)
• Establishment of IFE correction theory (A-10, A-15)
• Analysis of rare samples such as meteorites and polar deposits
• Fouling substances in membranes for water treatment
• Comparison with solid-state ¹³C-NMR spectroscopy

Estimation of the origin of rainwater derived infiltration and inflow (RDII) by focusing on “water quality”

• EEM spectroscopy and PARAFAC
• Bacterial community structure
• Inorganic ion
• Orbitrap-MS / ¹H-NMR spectroscopy

Diagnosis of water environment and water treatment process by image analysis

• Activated sludge floc (sedimentation, dewatering, bacterial adsorption capacity) (A-11, A-21, B-3, OP-3, OP-6, PP-5)
• Quantification of filamentous bacteria (A-18)
• Suspended solids (SS) (A-18, A-21)
• Anaerobic digestion sludge (dewatering)
• Biofilm and periphyton
• Moving image analysis of activated sludge sedimentation and coagulation (A-21, OP-3, PP-6)

Analytical chemistry for sensor development (B-2)

1. Development and application of a colorimetric method for DNA and RNA using DNA-modified gold nanoparticles

• Method development and mechanism elucidation (A-9, A-12)
• Ammonia oxidizing bacteria (A-9, A-12)
• Enterohaemorrhagic Escherichia coli (O157) (A-9)
• Coronavirus
• Influenza virus

2. Simple, rapid and multi-sample quantification of bacteria by microplate reader (MPR) and specific enzyme substrate medium

• Escherichia coli (A-13)
• Total coliform
• Antibiotic-resistant enterococci and Pseudomonas aeruginosa

3. Development of DNA aptamers

• Arsenic (A-7)
• Legionella pneumophila

Elucidation of adsorption mechanism of activated sludge

• Kinetic analysis (PP-7)
• Adsorption isotherm
• Adsorption of Escherichia coli (A-16, OP-6)
• Adsorption of suspended solids (A-18, A-21)
• Simple analysis of surface physicochemical characteristics

Analysis of the water environment

• Diffusion of sewage and treated sewage into the environment
• EEM spectroscopy and PARAFAC
• Bacterial community structure
• Inorganic ion
• Orbitrap-MS / ¹H-NMR spectroscopy
• Tracing antibiotics and antibiotic-resistance genes
• Regrowth of Escherichia coli
• Classification of COD (natural or anthropogenic)

Wastewater surveillance focusing on pharmaceutical ingredients in wastewater

• Antipyretic analgesics
• Antibiotics
• Medicines for lifestyle-related diseases
• Supplements

Exploration of unknown bacteria and functions; Establishment of Culture Method

• Substrate depletion tracking (A-8)
• PET Manufacturing Wastewater Treatment (A-8, A-17)
• Granule (A-14)

Formation and decomposition of humic substances in geochemical time scale

• Kinetics of the Maillard reaction (A-1, A-2, A-3, A-4, PP-1, PP-2, PP-3, PP-4)
•  Hydrothermal decomposition of humic substances (A-4)
• CO₂ production from humic substances (A-6)
• Organic / inorganic interaction kinetics (A-3, A-6, PP-4)

Publications

Books

• Nakaya, Y. and Nakashima, S. (2020)
  “5-3 Shionoyu hot spring”
  in: Hot springs in Japan, Supervised by The Japanese Society of Hot Spring Sciences, Asakura Publishing, p123. (in Japanese)

A. Original Papers

• A-1. Nakaya, Y. and Nakashima, S. (2016)
  In situ IR transmission spectroscopic observation and kinetic analyses of initial stage of the Maillard reaction as a simulated formation process of humic substances.
  Chemistry Letters, 45, 1204-1206, doi:10.1246/cl.160596
• A-2. Nakaya, Y., Nakashima, S. and Moriizumi, M. (2018)
  Non-destructive spectroscopic tracing of simulated formation processes of humic-like substances based on the Maillard reaction.
  Applied Spectroscopy,  72, 1189-1198, doi: 10.1177/0003702818775737
• A-3. Nakaya, Y., Okada, K., Ikuno, Y. and Nakashima, S. (2018)
  Spectroscopic study of effects of goethite surfaces on the simulated maillard reaction forming humic-like substances.
  e-Journal of Surface Science and Nanotechnology, 16, 411-418, doi: 10.1380/ejssnt.2018.411
• A-4. Nakaya, Y., Nakashima, S. and Otsuka, T. (2019)
  Evaluation of kinetic competition among formation and degradation processes of dissolved humic-like substances based on hydrothermal reactions measured by Ultraviolet–visible spectroscopy.
  Geochemical Journal, 53, 407-414, doi: 10.2343/geochemj.2.0575
• A-5. Nakaya, Y., Nakashima, S., Moriizumi, M., Oguchi, M., Kashiwagi, S. and Naka, N. (2020)
  Three dimensional excitation-emission matrix fluorescence spectroscopy of typical Japanese soil powders.
  Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 233, 118188,
  doi: 10.1016/j.saa.2020.118188
• A-6. Nakaya, Y., Nakashima, S. and Otsuka, T. (2021)
  Gas Cell Infrared and Attenuated Total Reflection Infrared Spectroscopic Studies for Organic-Inorganic Interactions in Adsorption of Fulvic Acid on the Goethite Surface Generating Carbon Dioxide.
  Applied spectroscopy, 75, 1114-1123,
  Online published, doi: 10.1177/0003702821991219
• A-7. Matsunaga, K., Nakaya, Y. and Satoh, H. (2022)
  Separate determination of arsenite and arsenate in groundwater samples by simple analytical methods.
  Water Supply, 22, 7635-7672,
  doi: 10.2166/ws.2022.331
• A-8. Kuroda, K., Narihiro, T., Nakaya, Y., Noguchi, T. Q. P., Maeda, R., Nobu, M. K., Ohnishi, Y., Kumaki, Y., Aizawa, T. and Satoh, H. (2022)
  Elucidation of the biodegradation pathways of bis(2-hydroxyethyl) terephthalate and dimethyl terephthalate under anaerobic conditions revealed by enrichment culture and microbiome analysis.
  Chemical Engineering Journal, 450, 137916.
  doi: 10.1016/j.cej.2022.137916
• A-9. Satoh, H., Nakajima, M., Hirano, R. and Nakaya, Y. (2022)
  Highly sensitive and homogeneous detection of unamplified RNA based on the light scattering properties of gold nanoparticle probes.
  Biosensors and Bioelectronics: X, 12, 100249.
  doi: 10.1016/j.biosx.2022.1
• A-10. Nakaya, Y., Tomita, A., Ochiai, K. and Yamamura, H. (2023)
  Quantification of organic fluorophores in absorbing media by solid-phase fluorescence excitation–emission matrix (SPF-EEM) spectroscopy of modeled mixtures containing bovine serum albumin (BSA) and colorants.
  Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 285, 121885.
  doi: 10.1016/j.saa.2022.12
• A-11. Nakaya, Y., Jia, J. and Satoh, H. (2023)
  Tracing morphological characteristics of activated sludge flocs by using a digital microscope and their effects on sludge dewatering and settling.
  Environmental Technology, 45, 4042-4052. doi: 10.1080/09593330.2023.2240026
• A-12. Nakajima, M., Hirano, R., Nakaya, Y. and Satoh, H. (2023)
  Analysis of Unamplified 16S rRNA of Ammonia-Oxidizing Bacteria in Activated Sludge by Spectrophotometry Using Gold Nanoprobes.
  ACS EST Water, 3, 3113-3120. doi: 10.1021/acsestwater.3c00265
• A-13. Shayan, M. N. M., Tanaka, Y., Hirano, R., Nakaya, Y. and Satoh, H. (2023)
  A simple and rapid method for detecting fecal pollution in urban rivers by measuring the intrinsic β-D-glucuronidase activity of Escherichia coli.
  Water Research, 246, 120689. doi: 10.1016/j.watres.2023.120689
• A-14. Oshiki, M., Saito, T., Nakaya, Y., Satoh, H. and Okabe, S. (2023)
  Growth of the Nitrosomonas europaea cells in the biofilm and planktonic growth mode: Responses of extracellular polymeric substances production and transcriptome.
  Journal of Bioscience and Bioengineering, 136, 430-437. doi: 10.1016/j.jbiosc.2023.10.002
• A-15. Nakaya, Y., Tomita, A. and Yamamura, H. (2024)
  Solid-phase fluorescence: Reproducibility and comparison with the solution states.
  Talanta, 270, 125566. doi: 10.1016/j.talanta.2023.125566
• A-16. Nakaya, Y., Nagahashi, N., Hirano, R., Ishizuka, Y. and Satoh, H. (2024)
  Physicochemical parameters affecting the adhesion of ciprofloxacin-resistant Escherichia coli to activated sludge.
  Water Science & Technology, 89, 2457-2467. doi: 10.2166/wst.2024.134
• A-17. Kuroda, K., Takai, M., Sekiguchi, T., Ikarashi, T., Kurashita, H., Nakajima, M, Nobu, M. K., Hatamoto, M., Yamaguchi, T.,  Nakaya, Y., Satoh, H., Yamauchi, M., Yamada, M. and  Narihiro, T. (2024)
  Development of an internal two-stage upflow anaerobic reactor integrating biostimulation strategies to enhance the degradation of aromatic compounds in wastewater from purified terephthalic acid and dimethyl terephthalate manufacturing processes.
  Water Research, 258, 121762. doi: 10.1016/j.watres.2024.121762
• A-18. Kaushalya, U., Nakaya, Y., Ishizaki, S., Sugino, K., Hirano, R., Satoh, H. (2025)
  Quantification of morphological characteristics and filamentous bacteria in activated sludge flocs through quantitative image analysis techniques incorporating image-processing software and U-Net deep-learning framework.
  Journal of Water Process Engineering, 70, 107053.  doi: 10.1016/j.jwpe.2025.107053
• A-19. Mohomed Shayan, N. M., Onodera, T., Hirano, R., Kuroda, K., Narihiro, T., Nakaya, Y., Satoh, H. (2025)
  Effects of snowmelt runoff on bacterial communities and antimicrobial resistance gene concentrations in an urban river in a cold climate region.
  Environmental Science and Pollution Research, 32, 7641–7650. doi: 10.1007/s11356-025-36168-y
• A-20. Nakaya, Y., Hirose, T., Tamori, R., Fujitake, N., Nakashima, S., Yamamura. H., Satoh, H. (2025)
  Solid-phase fluorescence excitation-emission matrix spectroscopy of soil, fulvic acid fractions, and clay mineral complexes: Evidence from red shift of fluorescence maxima associated with aggregation.
  Environmental Research, 279, 121900. doi: 10.1016/j.envres.2025.121900
• A-21. Nakaya, Y., Sugino, K., Ishizaki, S., Hirano, R., Noda, S., Moniwa, S., Hiraoka, Y., Satoh, H. (2025)
  Characterizing the Settlement of Activated Sludge Based on AI-Assisted Analysis of Moving and Still Images.
  ACS EST Water, 5(8), 4887–4896. doi: 10.1021/acsestwater.5c00539

Presentation List

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