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谷本 和也*; 加藤 真悟*; 徳永 紘平; 濱村 奈津子*; 大熊 盛也*; 光延 聖*
Environmental Microbiology, 27(12), p.e70212_1 - e70212_18, 2025/12
被引用回数：0 パーセンタイル：0.00(Microbiology)Geomicrobiology of copper (Cu) and iron (Fe) in circumneutral-pH drainage from a Japanese Cu mine was investigated, with a focus on Fe(II)-oxidising microorganisms. Cu in the drainage was rapidly removed through Fe(II) oxidation and subsequent Fe(III) biomineralisation. The resulting Fe(III) biomineral-rich sediment contained up to 2 wt% Cu, a percent-level high content. XAFS and XRD analyses directly demonstrated that Cu was predominantly associated with poorly crystalline Fe(III) oxyhydroxides. This study high-lights the potential of Fe(II)-oxidising bacteria for Cu bioremediation and biomineralisation under circumneutral-pH conditions.
内島 智貴*; 加藤 真悟*; 谷本 和也*; 白石 史人*; 濱村 奈津子*; 徳永 紘平; 牧田 寛子*; Kondo, Momoko*; 大熊 盛也*; 光延 聖*
FEMS Microbiology Ecology, 101(6), p.fiaf051_1 - fiaf051_15, 2025/05
被引用回数：3 パーセンタイル：75.49(Microbiology)鉄をエネルギー源として生きる鉄酸化細菌は、地下水や温泉、湿地など自然界のさまざまな場所に広く分布し、鉄の酸化反応を通じて地球規模の鉄循環に寄与している。さらに、彼らが作り出す鉄酸化物は、ヒ素や銅などの有害元素を強く吸着・固定する能力を持つことから、環境浄化にも応用されている。しかし、このように重要な役割を担っているにもかかわらず、多くの鉄酸化細菌は実験室で純粋培養できず、非常に培養が難しい微生物として知られてきた。実際、陸上環境の独立栄養性鉄酸化細菌の純粋培養報告は世界で8例程度にとどまっており、その生態解明や工学応用は進んでいない。本研究では、これまで純粋培養が非常に難しかった鉄酸化細菌の培養効率を大幅に向上する方法「オーダーメイド培地法」を確立した。本成果は、培養困難だった鉄酸化細菌の生理・生態の解明に向けた重要な一歩となる。また、鉄酸化細菌は地下水や河川水などに含まれる有害物質の浄化に利用される有用微生物であり、本成果は微生物利用型の環境修復(バイオレメディエーション)技術への応用が期待される成果である。
大熊 隆太郎*; 古府 麻衣子; 浅井 晋一郎*; Avdeev, M.*; 幸田 章宏*; 岡部 博孝*; 平石 雅俊*; 竹下 聡史*; 小嶋 健児*; 門野 良典*; et al.
Nature Communications (Internet), 12, p.4382_1 - 4382_7, 2021/07
被引用回数：10 パーセンタイル：59.81(Multidisciplinary Sciences)Dimensionality is a critical factor in determining the properties of solids and is an apparent built- in character of the crystal structure. However, it can be an emergent and tunable property in geometrically frustrated spin systems. Here, we study the spin dynamics of the tetrahedral cluster antiferromagnet, pharmacosiderite, via muon spin resonance and neutron scattering. We find that the spin correlation exhibits a two-dimensional characteristic despite the isotropic connectivity of tetrahedral clusters made of spin 5/2 Fe
ions in the three-dimensional cubic crystal, which we ascribe to two-dimensionalisation by geometrical frustration based on spin wave calculations. Moreover, we suggest that even one-dimensionalisation occurs in the decoupled layers, generating low-energy and one-dimensional excitation modes, causing large spin fluctuation in the classical spin system.
Lustikova, J.*; 塩見 雄毅*; 横井 直人*; 壁谷 典幸*; 木村 憲彰*; 家永 紘一郎*; 金子 真一*; 大熊 哲*; 高橋 三郎*; 齊藤 英治
Nature Communications (Internet), 9, p.4922_1 - 4922_6, 2018/11
被引用回数：51 パーセンタイル：88.26(Multidisciplinary Sciences)A rectenna, standing for a rectifying antenna, is an apparatus which generates d.c. electricity from electric fluctuations. It is expected to realize wireless power transmission as well as energy harvesting from environmental radio waves. To realize such rectification, devices that are made up of internal atomic asymmetry such as an asymmetric junction have been necessary so far. Here we report a material that spontaneously generates electricity by rectifying environmental fluctuations without using atomic asymmetry. The sample is a common superconductor without lowered crystalline symmetry, but, just by putting it in an asymmetric magnetic environment, it turns into a rectifier and starts generating electricity. Superconducting vortex strings only annihilate and nucleate at surfaces, and this allows the bulk electrons to feel surface fluctuations in an asymmetric environment: a vortex rectenna. The rectification and generation can be switched on and off with only a slight change in temperature or external magnetic fields.
