Springer Science and Business Media LLCActa Medica Okayama1557-1963212026Surface Plasmon Resonances in Silver Nanodendrites : Trunk Length and Branch Connectivity Dependence22472258ENQingyuanMaGraduate School of Informatics and Engineering, The University of Electro-communicationsYukiKishidaGraduate School of Informatics and Engineering, The University of Electro-communicationsNobuyukiTakeyasuGraduate School of Natural Science and Technology, Okayama UniversitySatoruShojiGraduate School of Informatics and Engineering, The University of Electro-communicationsThis study systematically investigates how trunk length and branch connectivity govern surface plasmon resonances in silver nanodendrites in the infrared (IR) region using a computational modeling strategy. We show that a continuous conductive trunk is essential for exciting long-wavelength collective plasmon modes. In a simulated bottom-up construction scheme, the trunk length is gradually increased to conductively connect additional branches to the backbone. Our results reveal that the fundamental Ā mode resonance can be deterministically tuned across the mid-infrared spectrum (from 3840 nm to 4360 nm) primarily by controlling the trunk connectivity. As the number of connected branches grows, the lowest-order collective resonance peak exhibits a systematic redshift, and its resonance wavelength scales linearly with the effective dipole length Leff of the electron oscillation path. Concurrently, new higher-order modes emerge as local resonances of the connected substructures. These observations indicate that interrupting the conductive pathway causes a global collective mode to decompose into multiple resonances associated with more weakly coupled subsystems. The established linear scaling relationship provides a highly predictable design rule for this gprogrammableh connectivity, offering a robust platform for advanced applications such as multi-spectral infrared imaging, selective chemical sensing, and surface-enhanced infrared absorption (SEIRA) spectroscopy, where precise, a priori control over narrow-band infrared resonances is essential.
No potential conflict of interest relevant to this article was reported.Springer Science and Business Media LLCActa Medica Okayama0947-839613192025Optical and chemical properties of silver tree-like structure treated with gold galvanic substitution744ENKazushiHondaGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityNobuyukiTakeyasuGraduate School of Environmental, Life, Natural Science and Technology, Okayama UniversityGalvanic gold substitution was executed in the presence of trisodium citrate on silver tree-like structures. No discernible difference in geometry was observed between the pre- and post-gold substitution phases, which benefited from the presence of citrate ions. The extent of gold substitution was regulated by the amount of gold ion solution added. After the gold substitution, an increase in extinction was observed in the ultraviolet region, indicating that gold was deposited at the surface. Raman scattering of para-toluenethiol was measured on the gold/silver tree-like structures at 488 nm excitations, where a decrease in the Raman peak intensity was observed as the quantity of gold ion solution increased. The results indicated that the optical property of silver was lost due to the increase of the amount of gold deposition. Concurrently, an investigation was conducted into the chemical resistance of the gold/silver tree-like structures, which was evaluated by measuring the resistivity inverse-proportional to the amount of silver ions dissolved by the diluted nitric acid. As the amount of gold ion solution added increased, the resistivity increased and became constant. The result implied that the surface chemical property had undergone a complete transformation into gold.No potential conflict of interest relevant to this article was reported.Elsevier BVActa Medica Okayama0021-97976292023Acidic layer-enhanced nanoconfinement of anions in cylindrical pore of single-walled carbon nanotube238244ENTakahiroOhkuboDepartment of Chemistry, Graduate School of Natural Science and Technology, Okayama UniversityHirokiNakayasuDepartment of Chemistry, Graduate School of Natural Science and Technology, Okayama UniversityYukiTakeuchiDepartment of Chemistry, Graduate School of Natural Science and Technology, Okayama UniversityNobuyukiTakeyasuDepartment of Chemistry, Graduate School of Natural Science and Technology, Okayama UniversityYasushigeKurodaDepartment of Chemistry, Graduate School of Natural Science and Technology, Okayama UniversityThe adsorption of the nitrate ion by the cylindrical pore of single-walled carbon nanotubes (SWCNT) was found to be aided by an acidic adsorbed layer. Adsorbed water in the vicinity of the pore wall can supply protons through ionization, forming the acidic layer, according to Raman spectra and results of solution pH fluctuations caused by ion species adsorption. Such an acidic adsorbed layer leads to surplus adsorption of anionic species where the adsorbed amount of nitrate ions is much larger than that of cations. Also, we could observe the Raman bands being assignable to the symmetrical stretching mode at an extremely highfrequency region for nano-restricted nitrate ions compared to any other bulk phases. The abnormal band shift of adsorbed nitrate ions indicates that the nitrate ions are confined in the pore under the effects of nanoconfinement by the pore and the strong interaction with the acidic layer in the pore. Our results warn that we have to construct the adsorption model of aqueous electrolytes confined in carbon pores by deliberating the acid layer formed by the adsorbed water.No potential conflict of interest relevant to this article was reported.ElsevierActa Medica Okayama003991401222014Speciation of arsenic in a thermoacidophilic iron-oxidizing archaeon, Acidianus brierleyi, and its culture medium by inductively coupled plasma–optical emission spectroscopy combined with flow injection pretreatment using an anion-exchange mini-column240245ENNaokiHigashidaniTakashiKanetaNobuyukiTakeyasuShojiMotomizuNaokoOkibeKeikoSasakiThe thermoacidophilic iron-oxidizing archaeon Acidianus brierleyi is a microorganism that could be useful in the removal of inorganic As from wastewater, because it simultaneously oxidizes As(III) and Fe(II) to As(V) and Fe(III) in an acidic culture medium, resulting in the immobilization of As(V) as FeAsO4. To investigate the oxidation mechanism, speciation of the As species in both the cells and its culture media is an important issue. Here we describe the successive determination of As(III), As(V), and total As in A. brierleyi and its culture medium via a facile method based on inductively coupled plasma–optical emission spectroscopy (ICP–OES) with a flow injection pretreatment system using a mini-column packed with an anion-exchange resin. The flow-injection pretreatment system consisted of a syringe pump, a selection valve, and a switching valve, which were controlled by a personal computer. Sample solutions with the pH adjusted to 5 were flowed into the mini-column to retain the anionic As(V), whereas As(III) was introduced into ICP–OES with no adsorption on the mini-column due to its electrically neutral form. An acidic solution (1 M HNO3) was then flowed into the mini-column to elute As(V) followed by ICP–OES measurement. The same sample was also subjected to ICP–OES without being passed through the mini-column in order to determine the total amounts of As(III) and As(V). The method was verified by comparing the results of the total As with the sum of As(III) and As(V). The calibration curves showed good linearity with limits of detection of 158, 86, and 211 ppb for As(III), As(V), and total As, respectively. The method was successfully applicable to the determination of the As species contained in the pellets of A. brierleyi and their culture media. The results suggested that the oxidation of As(III) was influenced by the presence of Fe(II) in the culture medium, i.e., Fe(II) enhanced the oxidation of As(III) in A. brierleyi. In addition, we found that no soluble As species was contained in the cell pellets and more than 60% of the As(III) in the culture medium was oxidized by A. brierleyi after a 6-day incubation.No potential conflict of interest relevant to this article was reported.Elsevier Science B.V.Acta Medica Okayama0021967312882013Determination of association constants between 5 '-guanosine monophosphate gel and aromatic compounds by capillary electrophoresis149154ENKaoriYamaguchiNobuyukiTakeyasuTakashiKanetaHydro gel formed by 5'-guanosine monophosphate (GMP) in the presence of a potassium ion is expected to exhibit interesting selectivity in capillary electrophoretic separations. Here, we estimated the conditional association constants between the hydro gel (G-gel) and aromatic compounds by capillary electrophoresis in order to investigate the separation selectivity that is induced by the G-gel. Several aromatic compounds were separated in a solution containing GMP and potassium ion at different concentrations. The association constants were calculated by correlating the electrophoretic mobilities of the analytes obtained experimentally using a concentration of G-gel. During semi-quantitative estimation, naphthalene derivatives had larger association constants (K-ass = 10.3-16.8) compared with those of benzene derivatives (K-ass = 3.91-5.31), which means that the binding sites of G-gel match better to a naphthalene ring than to a benzene ring. A hydrophobic interaction was also found when the association constants for alkyl resorcinol were compared with those of different hydrocarbon chains. The association constants of nucleobases and tryptophan ranged from 6.05 to 12.6, which approximated the intermediate values between benzene and naphthalene derivatives. Consequently, the selective interaction between G-gel and aromatic compounds was classified as one of three types: (1) an intercalation into stacked planar GMP tetramers; (2) a hydrophobic interaction with a long alkyl chain; or, (3) a small contribution of steric hindrance and/or hydrogen bonding with functional groups such as amino and hydroxyl groups.No potential conflict of interest relevant to this article was reported.