Research Themes

• 培養からの脱却による培養困難なウイルスの浄水処理性評価法の創造
  科学研究費助成事業
  Apr. 2025 - Mar. 2028
  松下 拓
  日本学術振興会, 基盤研究(A)（代表）, 北海道大学, 25H00749
• 有機フッ素化合物の持続可能な活用のための浄水処理法の開発と勘案すべき物性の提案
  科学研究費助成事業
  Jun. 2024 - Mar. 2026
  松下 拓
  日本学術振興会, 挑戦的研究(萌芽)（代表）, 北海道大学, 24K21624
• 単離技術と遺伝子操作系を駆使した遺伝的に多様な病原ウイルスの浄水消毒処理性評価
  科学研究費助成事業
  01 Apr. 2022 - 31 Mar. 2025
  白崎 伸隆, 松下 拓
  本研究では，国内の水道原水中から複数の遺伝子型・株の病原ウイルスを単離すると共に，ウイルスの遺伝情報と遺伝子操作系であるリバースジェネティクス法を活用することにより，単離による入手が困難な複数の遺伝子型・株の病原ウイルスを人工合成し，これらを消毒処理（塩素処理，オゾン処理，紫外線処理等）の室内実験に用いることにより，遺伝子型・株の差異によってどの程度病原ウイルスの消毒処理性が異なるのか，また，どのような要因によって消毒処理性に差異が生じるのかを明らかにすることを目的とした．
  今年度は，エンテロウイルスの宿主細胞であるBGM細胞及びロタウイルスの宿主細胞であるMA104細胞を用いた感染力評価手法を適用すると共に，環境水中から病原ウイルスを感染力を保持した状態で回収・濃縮可能な新たなウイルス濃縮法を検討・適用することにより，国内の水道原水に存在する感染力を有するエンテロウイルス及びロタウイルスを回収・濃縮することに成功した．一方，消毒処理においては，タンジェンタルフローUF膜によるウイルス高倍率濃縮を組み合わせた大容量の塩素処理実験系及びオゾン処理実験系を検討し，ウイルス高倍率濃縮を実施しない小容量の実験系と同様の病原ウイルスの消毒処理性評価結果が得られること，すなわち，構築した大容量の実験系が塩素処理及びオゾン処理における病原ウイルスの消毒処理性の詳細把握（高不活化率の把握及び不活化メカニズムの議論）に適用できることを確認した．
  日本学術振興会, 基盤研究(B), 北海道大学, 23K22889
• 単離技術と遺伝子操作系を駆使した遺伝的に多様な病原ウイルスの浄水消毒処理性評価
  科学研究費助成事業
  01 Apr. 2022 - 31 Mar. 2025
  白崎 伸隆, 松下 拓
  日本学術振興会, 基盤研究(B), 北海道大学, 22H01619
• 超微粉炭プレコートと超高塩基度PACl凝集によるファウリングフリー膜ろ過
  科学研究費助成事業
  05 Apr. 2021 - 31 Mar. 2024
  松井 佳彦, 松下 拓, 白崎 伸隆
  日本学術振興会, 基盤研究(A), 北海道大学, 21H04567
• 遺伝子組換と非ウイルスベクター技術を用いた培養に頼らないウイルスの浄水処理性評価　　　　　　　　　　　　　　　
  基盤研究(A)（代表）
  2022 - 2024
  松下 拓
  日本学術振興会, Principal investigator
• Novel manganese treatment process by oxidative superfine activated carbon
  Grants-in-Aid for Scientific Research
  09 Jul. 2021 - 31 Mar. 2023
  松井 佳彦, 松下 拓
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Research (Exploratory), Hokkaido University, 21K18736
• Evaluating the efficacy of drinking water treatment processes to remove and inactivate diversified human enteric viruses present in drinking water sources
  Grants-in-Aid for Scientific Research
  01 Apr. 2019 - 31 Mar. 2022
  Nobutaka Shirasaki
  We investigated the occurrence of human enteric viruses in drinking water sources by using PCR and PMAxx-Enhancer-PCR which can detect damage to viral capsids. We then successfully evaluated the reduction efficiencies of a human enteric virus and pepper mild mottle virus, a potential surrogate for human enteric viruses to assess virus removal by coagulation-microfiltration, in an actual drinking water treatment plant employing coagulation-microfiltration. In addition, DNA-encapsulated virus-like particles that can be quantified by PCR were successfully constructed by using DNA-conjugated gold nanoparticles.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 19H02269
• Innovative Water Treatment System Combining Pretreatments and Membrane Separation for Sustainable Supply of Safe High-quality Water
  Grants-in-Aid for Scientific Research
  31 May 2016 - 31 Mar. 2021
  Matsui Yoshihiko
  Superfine powdered activated carbon (SPAC), whose particle size is decreased to 140 nm, is excellent at adsorptive removal of biopolymers, which causes membrane fouling, and we proposed SPAC-precoated membrane filtration with almost no increase in the transmembrane pressure due to membrane fouling. SPAC is effective as a catalyst for the oxidation of dissolved Mn(II) ion in the presence of chlorine, and a new treatment method was proposed in which manganese was oxidized and deposited on the SPAC surface and separated by the membrane. We succeeded in developing a high-basicity polyaluminum chloride coagulants that are excellent in removing SPAC, arsenic, and viruses and clarified that its applicability varies depending on the sulfate ion in the raw water. Synergistic accelerated oxidative decomposition by VUV and ozone microbubbles and reductive decomposition by VUV were found, which indicates the possibility of efficient treatment of persistent per- and polyfluoroalkyl substances.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 16H06362
• 培養に頼らないウイルスの浄水処理性評価手法と高効率浄水ウイルス処理システムの構築　　　　　　　　　　　　　　　
  基盤研究(A)（代表）
  2018 - 2021
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• 「見える」ファウリング物質を用いた膜ファウリングメカニズムの根本的解明　　　　　　　　　　　　　　　
  挑戦的研究（萌芽）（代表）
  2019 - 2020
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• 代謝を考慮したコリンエステラーゼ活性阻害試験の構築とそれを用いた有機リン系農薬由来分解物の毒性評価　　　　　　　　　　　　　　　
  フソウ技術開発振興基金研究助成（代表）
  2018 - 2019
  松下 拓
  フソウ技術開発振興基金, Principal investigator, Competitive research funding
• ＤＮＡを封入したウイルス外套蛋白粒子を用いた培養困難なウイルスの浄水処理性評価　　　　　　　　　　　　　　　
  挑戦的研究（萌芽）（代表）
  2017 - 2018
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• 有機リン系農薬の塩素処理工程における毒性の変動と毒性に寄与する分解生成物の同定　　　　　　　　　　　　　　　
  フソウ技術開発振興基金研究助成（代表）
  2017 - 2018
  松下 拓
  フソウ技術開発振興基金, Principal investigator, Competitive research funding
• Innovative Water Treatment Technology Combining Advanced Unit Processes and Membrane Separation
  Grants-in-Aid for Scientific Research
  31 May 2012 - 31 Mar. 2017
  Matsui Yoshihiko
  Regarding super-fine powdered activated carbon, the mechanism of the Shell Adsorption Model to explain high adsorption capacity was verified. Low competitive adsorption, high removal of radioactive iodine, optimum particle size, and the reuse of spent granular activate carbon were revealed. Regarding poly-aluminum coagulant, effective species for low residual aluminum and high virus removal and their production conditions were found. Basic characteristics of normal and vacuum ultraviolet decompositions were studied. Degradation products were evaluated for their safety assessment. Regarding membrane filtration, lower membrane fouling attained by high-basicity poly-aluminum coagulant were related to aluminum particles size and silicate.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (S), Hokkaido University, 24226012
• 遺伝子組換で発現した外套タンパクを用いた培養不可能なウイルスの浄水処理性の評価　　　　　　　　　　　　　　　
  基盤研究(B)（代表）
  2015 - 2017
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• ヒト嗅覚を検出器としたGC/MS法の確立とそれを用いた浄水異臭味の全体像の把握　　　　　　　　　　　　　　　
  挑戦的萌芽研究（代表）
  2015 - 2016
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• Isotope Microscopy Visualization of Adsorption Profile Verifies the Mechanism of Higher Adsorption Capacity on Super-fine Powdered Activated Carbon
  Grants-in-Aid for Scientific Research
  01 Apr. 2013 - 31 Mar. 2015
  MATSUI Yoshihiko, MATSUSHITA Taku
  Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for some compounds, such as geosmin, 2-methylisoborneol, and polystyrene sulfonates. Shell adsorption model (SAM), in which adsorbates preferentially adsorb near the exterior surface of the adsorbent particle, may explain this enhancement. This study used isotope microscopy and deuterium-labeled adsorbates to directly visualize the solid-phase concentration profiles of these compounds in carbon particles. The deuterium/hydrogen ratio, which was used as an index of the solid-phase concentration of the adsorbates, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by SAM analyses of isotherm data. The direct visualization of the localization of compounds in carbon particles explained the mechanism of the equilibrium adsorption capacity enhancement.
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 25550049
• VLPsを用いた培養不可能なウイルスの浄水処理性評価　　　　　　　　　　　　　　　
  基盤研究(B)（代表）
  2012 - 2014
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• Ultrafine microparticulation of adsorbents breaksadvanced membrane process
  Grants-in-Aid for Scientific Research
  11 May 2009 - 31 Mar. 2013
  MATSUI Yoshihiko, MATSUSHITA Taku, OHNO Koichi
  The capacity to adsorb natural organic matter (NOM) and polystyrene sulfonates (PSSs) on super-fine powdered-activated carbon (SPAC) is higher than that on conventional powdered-activated carbon (PAC). Increased adsorption capacity was due to the larger external surface area because the NOM and PSS molecules did not completely penetrate the adsorbent particle; they preferentially adsorbed near the outer surface of the particle. The results of field emission scanning electron microscopy/energy-dispersive X-ray spectrometry provided the direct evidence of this phenomenon. We also successfully proposed the Shell Adsorption Model (SAM) to describe quantitatively adsorption isotherms of different carbon particle sizes. The adsorption kinetics was well described by SAM + Branched Pore Kinetic Model. The use of SPAC in the coagulation pretreatment for membrane microfiltration attenuates trans-membrane pressure increases as well as enhancing the dissolved substance removal. The mechanism was explained on coagulation theory: floc particle size, particle-particle collision frequency, and NOM removal.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), Hokkaido University, 21246083
• Elucidating adsorption mechanism of super-fine powdered activated carbon by isotope-imaging
  Grants-in-Aid for Scientific Research
  2011 - 2012
  MATSUI Yoshihiko, MATSUSHITA Taku
  Geosmin and 2-methylisoborneol (MIB) adsorption capacity dependency on activated carbon particle size was investigated for two carbons. By using the isotope microscope system and carbon particles loaded with deuterium-doped MIB and geosmin, isotopic maps for deuterium/hydrogen ratio as a maker of MIB and geosmin were obtained. For a carbon in which the adsorption capacity to adsorb MIB and geosmin increased with decreasing carbon particle size, deuterium/hydrogen ratio was high on the exterior region close to the particle outer-surface compared with inner region. The result indicated the higher MIB and geosmin adsorption capacities on super-fine powdered activated carbon than on normal-size powdered activated carbon is explained by the shell adsorption mechanism. When MIB and geosmin adsorbs in internal pores of activated carbon particles, adsorption competition between natural organic matter (NOM) and these compounds does not increase when NOM uptake increased due to carbon size reduction.
  Japan Society for the Promotion of Science, Grant-in-Aid for Challenging Exploratory Research, Hokkaido University, 23656323
• VLPを用いたノロウイルスの浄水処理性評価　　　　　　　　　　　　　　　
  若手研究(A)（代表）
  2009 - 2011
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• 遺伝子組換で発現した外套タンパクを用いたノロウイルス浄水処理性の評価　　　　　　　　　　　　　　　
  クリタ水・環境科学振興財団助成（代表）
  2009 - 2010
  松下 拓
  クリタ水・環境科学振興財団, Principal investigator, Competitive research funding
• Advanced Water Treatment Technology by Super-powdered Adsorbent
  Grants-in-Aid for Scientific Research
  2007 - 2008
  MATSUI Yoshihiko, MATSUSHITA Taku, OHNO Koichi
  市販の粉末活性炭(Powdered activated carbon, PAC)を微粉砕し粒径が1μm以下のサブミクロン粒度の微粉炭(Suoper-powdered activated carbon, S-PAC)を製造し, 臭気物質ジェオスミンや2-メチルイソボルネオール(2-MIB), 自然由来有機物質(NOM)の吸着性, セラミック膜ろ過の吸着前処理として用いた際のそれらの除去性, および微粉炭添加が膜ろ過のろ過性に及ぼす影響について検討した. その結果, サブミクロン粒度まで微小化した微粉炭は, 少添加量, 短時間で吸着が進行し, 市販粉末活性炭に比べて, NOM やジェオスミン, 2-MIB の除去性が格段に優れていることが分かった. さらにNOM の吸着除去性の向上には, 吸着容量の増加によるものであることを見出した. 特に, NOM の中でもSUVA 値が高いフミン質的なNOM において吸着量の増加が顕著に見られた. 活性炭の微粉砕の前後で活性炭内部の細孔分布・容量に変化が見られず, 吸着容量の増加は, 高分子モデル物質ポリスチレンスルホン酸(PSS)では見られ, より分子量の大きいポリエチレングリコール(PEG)では見られないことから, 吸着容量増加は吸着質の化学的な性質が関与していると推定された. ジェオスミンを対象に微粉炭に対する吸着速度をhomogeneous surface diffusion model (HSDM)とbranched pore kinetic model (BPKM)で解析したところ, 活性炭粒子の微粒度化に伴い, 吸着除去速度の律速段階が, 粒子内のマクロ孔やメソ孔を通じた半径方向の拡散から, ローカルなミクロ孔の拡散へ移行することがわかった. そのためHSDM では見かけ上拡散係数が減少することになる. 微粉炭の粒度と吸着除去性の関連をBPKMで検討し, 除去対象をジェオスミンに想定した場合の最適粒径は1μm付近であり, 1μm以下まで粉砕しても除去効率の向上はあまりないことがわかった. 微粒度化は市販の木質, ヤシ殻, 石炭系のすべての活性炭で有効であることも確認した.
  膜の前処理としての微粉炭の添加は, 薬品洗浄までの長期的膜間差圧上昇のみならず逆洗浄までの短期的膜間差圧上昇の抑制にも効果的なことが分かった. この理由は微粉炭添加により膜ファウリング物質が活性炭へ吸着されるためと, 微粉炭添加により粒子間の衝突頻度が高まりさらに凝集剤消費物質であるNOMが予め吸着除去されるためにより大きな透水性の高いフロック粒子が形成されるためであることを明らかにした.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 19360235
• ウイルス外套タンパク粒子を用いたノロウイルスの浄水処理性の検討　　　　　　　　　　　　　　　
  若手研究(B)（代表）
  2007 - 2008
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• Investigation of the behavior of natural hormones and antibiotic compounds in river water bodies based on model watercourse experiments
  Grants-in-Aid for Scientific Research
  2005 - 2007
  LI Fusheng, SUZUKI Yutaka, YUASA Akira, MATSUSHITA Taku
  In addition to naturally-occurring humic molecules and metabolic products induced from biological wastewater treatment processes, a larger number of trace organic compounds occurred due to industrial and social activities have found their presence in most natural water sources, such as rivers and lakes. Among such compounds, 17 beta estradiol (E2) and estrone (El), together with veterinary antibiotics are greatly concerned due to their strong adversary impacts on humans and wildlife. lb preserve natural water bodies, particularly to alleviate and prevent the happening of tap water quality risk, clarification of the behavior of the concerned compounds, and thus to establish feasible examination and prediction approaches are particularly important, taking into account that relative literature information is very limited.
  In this study, natural hormones, which are widely detected in natural water bodies and are found possessing eminent safety risk, were chosen as the targets for investigation. By performing batch and continuous flow column experiments using the water and sediment samples from the mainstream and major tributaries of Nagara River and those from a freshwater dam reservoir, the dissipation behavior and mechanisms were investigated and corresponding data analysis was performed, so as to examine and predict their this in related water bodies. In addition, using activated sludge sampled from a conventional wastewater treatment plant, the behavior of natural hormones was studied, and the impacts of operational conditions and coexisting bio-degradable organic molecules were evaluated. In regard of the behavior of veterinary antibiotics, column experiments with fixed granular activated carbon pre-coated with microorganisms detached from riverbed mud of the mainstream of Nagara River were also performed. Through all these series of experiments, the dissipation behavior and mechanisms of targeted compounds were grasped, and several new findings that could benefit establishment of a systematic prediction approach were obtained.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Gifu University, 17360261
• Membrane filtration with rapid pretreatment using adsorbent of submicron particle size
  Grants-in-Aid for Scientific Research
  2005 - 2006
  MATSUI Yoshihiko, MATSUSHIMA Taku
  Normal manufacturer-supplied powdered activated carbon (PAC) was pulverized to reduce the PAC particle size to less than 1 μm; we call the pulverized PAC super-powdered activated carbon (S-PAC). Advantages of S-PAC over normal PAC, mainly in terms of adsorptive removal of natural organic matter (NOM) and geosmin (musty-earthy taste and odor compund), were studied. Batch adsorption kinetic tests and tubular flow reactor tests revealed that S-PAC rapidly adsorbed NOM from water samples. NOM concentration rapidly decreased after S-PAC addition and reached a plateau of practically attainable removal in a contact time of 5 s. Next, S-PAC adsorption as a pretreatment for microfiltration (MF) was studied by using laboratory-scale and bench-scale pilot plants. Use of S-PAC could decrease significantly the detention time for adsorption pretreatment before MF. A detention time of 2.4 s yielded the same NOM concentration in the MF permeate as a detention of 15 min. Use of S-PAC could also decrease the dosage compared with normal PAC by a factor of 1/4. The dosing sequence, PAC followed by coagulant and then MF, showed slightly better NOM removal than the sequence, coagulant followed by PAC and then MF, suggesting that flocculation of PAC particles somewhat hinders adsorbate uptake into PAC particles. Adsorption pretreatment by using this S-PAC removed the geosmin with vastly greater efficiency than by normal PAC. Removal was attained in a much shorter contact time and at a much lower dosage. The S-PAC was also beneficial in attenuating the trans-membrane pressure rises that occurred between both physical backwashings and chemical cleanings. No membrane fouling effect was observed as a result of S-PAC addition before MF.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 17360255
• 加水分解アルミニウムポリマーに対するウイルスの不可逆吸着と不活化
  科学研究費助成事業
  2004 - 2005
  松井 佳彦, 井上 隆信, 松下 拓
  本年度は,セラミックMF膜を用いた凝集MF膜処理について,異なる条件下におけるウイルス除去の比較・検討を行った.また,ウイルス除去のメカニズムについて調べるために,凝集MF膜処理におけるウイルスの物質収支をとることを試みた.
  PAC添加濃度,凝集時間,膜孔径,流束がウイルス除去に与える影響について検討した結果,凝集MF膜処理においてはPAC添加濃度の影響が最も大きかった.また,1.08mg/L as Al以上のPAC添加濃度では,どの条件下においても5log以上の高い除去率が得られた.原水間の比較では,濁度成分の高い原水の除去率は他の原水と比べて1log程度低くなった.また,ウイルス間においては,QβとMS2で除去率に差が見られた.さらに,全ての実験結果で,処理時間が経過するにつれて除去率が向上するという傾向が見られた.
  凝集MF膜処理におけるウイルスの物質収支については,逆圧洗浄を行うことによりMF膜エレメント内に保持されていると考えられるウイルス量の13%を回収することができた.また,未回収の87%については,ファウリング物質として膜の表面でなく膜孔内部に不可逆的に捕捉されている可能性,ならびに処理水中に流出されている可能性の二つが考えられた.
  日本学術振興会, 萌芽研究, 16656159
• 環境中での農薬の光／微生物分解に伴う遺伝子毒性の変動　　　　　　　　　　　　　　　
  若手研究(B)（代表）
  2004 - 2005
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• Development of determination method of bioavailable phosphorus using algal growth potential and sequence extraction and evaluation its runoff loading
  Grants-in-Aid for Scientific Research
  2002 - 2004
  INOUE Takanobu, MATSUI Yoshihiko, MATSUSHITA Taku
  The sequence extraction method and algal growth potential examinations were applied to suspended solids in river water and watershed soil of the Nagara River watershed and the Asutani River watershed. Particulate Phosphorus were separated and defined as 9 forms by the sequence extraction method. Only particulate phosphorus in suspended solids from the river water or the soil of the watersheds used in the algal growth potential examinations.
  The results of this study are the following :
  1)During storm events, the inorganic phosphorus compounds soluble in bases, organic phosphorus, and redox-sensitive phosphorus bound to Fe and Mn were dominated among the particulate phosphorus forms of the river water, and the content of these phosphorus forms in particulate phosphorus ranged from 75% to 90%. The ratio of bioavailable phosphorus to particulate phosphorus was between 30% and 40%.
  2)About 50% of total phosphorus in forest surface soil was organic, and about 40% in the paddy field surface soil was redox-sensitive phosphorus bound to Fe and Mn.
  3)The algal growth potential examination indicated that the particulate form of phosphorus could be available for algal growth.
  4)The algal growth potential examinations showed that the ratio of bioavailable phosphorus to total in forest surface soil and in paddy field surface soil were about 60% and 90%, respectively.
  5)The ratio of bioavailable phosphorus to particulate solids calculated by the sequence extraction method was higher than that by the algal growth potential examination.
  These results suggested that sequence extraction method is useful for the quantitative determination of bioavailable phosphorus in particulates. Further studies are necessary to know the reason of the difference between extracted sequence extraction method and bioavailability by algal growth potential examination.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), 14580548
• Virus Inactivation in Coagulants : Secondary Effect of Aluminum and Iron Coagulation Reactions
  Grants-in-Aid for Scientific Research
  2002 - 2004
  MATSUI Yoshihiko, INOUE Takanobu, MATSUSHITA Taku
  Inorganic aluminum salts, such as aluminum sulfate, are coagulants that cause small particles, such as bacteria and viruses as well as inorganic particles, to destabilize and combine into larger aggregates. In this investigation, batch coagulation treatments of water samples spiked with Qβ, MS2, T4, and P1 viruses were conducted with 4 different aluminum coagulants. The total infectious virus concentration in the suspension of floc particles that eventually formed by dosing with coagulant was measured after the floc particles were dissolved by raising the pH with an alkaline beef extract solution. The virus concentrations were extremely reduced after the water samples were dosed with aluminum coagulants. Viruses mixed with and adsorbed onto preformed aluminum hydroxide floc were, however, completely recovered after the floc dissolution. These results indicated that the aluminum coagulation process inactivates viruses. Virucidal activity was most prominent with the prehydrolyzed aluminum salt coagulant, polyaluminum chloride (PAC). Virucidal activity was lower in river water than in ultra-pure water-natural organic matter in the river water depressed the vrucidal activity. Mechanisms and kinetics of the virus inactivation were discussed. Our results suggest that intermediate polymers formed during hydrolysis of the aluminum coagulants sorbed strongly to viruses, either rendering them inactive or preventing infectivity.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Gifu University, 14350284
• 嫌気好気条件の変化に伴う環境化学物質の微生物分解代謝物の遺伝子毒性の変動　　　　　　　　　　　　　　　
  若手研究(B)（代表）
  2002 - 2003
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding
• Prediction of chemicals runoff m watershed based on the combined water and mass transfer model
  Grants-in-Aid for Scientific Research
  2001 - 2003
  YUASA Akira, INOUE Takanobu, SHINODA Seirou, MATSUI Yoshihiko, MATSUSHITA Taku, LI Fusheng
  A model analysis of chemicals runoff in watershed was constructed, based on the combination of chemicals transfer model and water transfer model. Watershed area was divided into grids of 1km x 1km and each grid was further divided vertically and horizontally to 13 compartments. The Chikugo River basin was analyzed in which agrochemical compounds were monitored frequently (five times per week). Runoff of agrochemicals used in paddy field was predicted.
  Data of land utilization were collected from digital map and information published by the National Geographical Survey Institute. Weather information was obtained from the AMEDAS data. River flow rate was estimated from the observed values at the observation points and the reserved volume and discharge flow rate at the reservoir dam.
  Data on farm work such as date and place of agrochemical sprinkling and spraying, date of rice transplanting, water management schedule are regarded uncertain. Characteristics of the agrochemical compound such as adsorption coefficient and biological decomposition rate constant are also regarded uncertain. The value of these parameters was set using Monte Carlo method based on the probability distribution of matters taking place. The conventional simulation by a deterministic algorithm was also applied for comparison. As a result, the following results were obtained.
  (1)Estimated concentration level of agrochemicals by the Monte Carlo simulation are more dosed to the actual observed value in rivers than that estimated by the deterministic algorithm. Thus, the Monte Carlo simulation was proved to give much accurate prediction. (2)It was indicated that runoff of an agrochemical compound can probably be estimated if the total amount of consumption of the compound in the whole watershed area is given, even though the precise schedule and accurate amount of agrochemical sprinkling in each paddy field are unknown.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Gifu University, 13838006
• Hybrid System of Adsorption and Membrane Separation
  Grants-in-Aid for Scientific Research
  2001 - 2003
  YUASA Akira, FUSHENG Li, INOUE Takanobu, MATSUI Yoshihiko, SATO Mikio, MATSUSHITA Taku
  This study describes several application potentials with a recently developed model for predicting the synthetic organic chemical (SOC) removal by powdered activated carbon (SAC) adsorption during ultrafiltration (UF) and discusses the removal mechanism. The model was successfully applied, without any modification, to dead-end mode operation as well as to cross-flow mode operation, validating the assumption of the internal diffusion control mechanism and the continuously-stirred-tank-reactor (CSTR) concept. Even when OF was operated in a cross-flow mode, PAC added was re-circulating in suspension for only a short time. Then, solute uptake took place mostly by PAC immobilized in membrane tubes not only for dead-end operation but also for cross-flow operation. Therefore, cross-flow operation did not have any advantage regarding the SOC mass transfer on PAC in OF loop over dead-end operation. The model simulation implied that pulse PAC addition at the beginning of filtration cycle resulted better SOC removal than continuous PAC addition. However, for the pulse PAC addition mode, the model predicted somewhat lower effluent SOC concentration than the observed values, and the benefit of pulse PAC application in terms of reducing SOC over its continuous dosage was not confirmed. Longer retention tune of PAC dosed in a pulse than continuously dosed PAC could possibly further decrease internal diffusivity
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Gifu University, 13555149
• Attachment Mechanism and Control Efficacy of an Adhesive Nuisance Mussel, Limnoperna fortunei, for Coating and Materials
  Grants-in-Aid for Scientific Research
  2000 - 2002
  MATSUI Yoshihiko, KUBO Toshihiro, YUASA Akira, YAMAMOTO Hiroyuki, MATSUSHITA Taku, INOUE Takanobu
  The attachment strength of the freshwater mussel Limnoperna fortunei against water flow was studied. Newton's expression successfully described the hydrodynamic drag force acting on the mussel with a drag coefficient value of 1.03. The drag-resistant force (defined as hydrodynamic drag force at mussel detachment) was smaller than the detachment force measured using a tensile load test. A fairly good correlation was obtained between the drag-resistant force and the number of secreted threads. The drag-resistant force divided by the number of threads increased with shell size, suggesting that byssal thread strength increased with mussel growth. For the mussel specimens obtained from a water transmission pipe, thread width increased with shell size. However, thread width was not dependent on current velocity. There was no correlation between the number of secreted threads and shell length, which indicated that the number of secreted threads did not change with mussel size. Therefore, the water velocity needed to detach mussels increases with shell size of the mussel when the number of secreted threads is constant. The increases in the water velocity to detach mussels with larger shell suggested that the mussel becomes more resistant to water flow as it grows. It is estimated that a flow velocity around 1 m/s was critical for attachment/detachment of a juvenile mussel with a shell length of a few millimeters and one hundred byssal threads.
  Various anti-fouling substrates were tested for their effectiveness in inhibiting attachment of Limnoperna fortunei. Field experiments revealed that surface properties affected anti-fouling capabilities for nontoxic substrates. Anti-fouling capabilities were observed for 3 silicone-resin-based coatings with smooth surfaces of < 30 μm roughness and low surface free energy of the hydrogen-bonding force component. However, the remaining 3 silicone-resin-based coatings tested, as well as other types of nontoxic coatings, did not show any anti-fouling capabilities. The percentages of mussels that attached in laboratory experiments using juvenile mussels were correlated with the settling densities of mussels in the field experiments. This suggests that the laboratory experiments may be effective as short-term preliminary assays to select promising materials/coatings for longer-term field experiments. Mussel abundance surveys within a water transmission pipe and pipe current velocity simulation revealed that less mussel infestation was observed in the areas with wall-vicinity fluid velocity of > 1.3 m/s. Conversely, pipe surfaces with flows of < 1.2 m/s were heavily fouled by L. fortunei.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Gifu University, 12558070
• 染色体異常誘発性と遺伝子毒性からみた環境化学物質の微生物分解の安全評価実験　　　　　　　　　　　　　　　
  奨励研究(A)（代表）
  2000 - 2001
  松下 拓
  日本学術振興会, Principal investigator, Competitive research funding