Hiromitsu Nakajima

Hiromitsu Nakajima
Saitama University · Graduate School of Science and Engineering

Doctor of Engineering
Res. on sci. education "Development of a cross-disciplinary scientific research program on mosses" of JSPS JP23K02809.

About

32
Publications
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618
Citations

Publications

Publications (32)
Article
Full-text available
Stereocaulon sorediiferum is expected to be a Cu-hyperaccumulator lichen and has fluorescent substances. To clarify the relationship between the fluorescence (FL) of the lichen and its Cu concentration, we collected S. sorediiferum samples at Cu-contaminated and uncontaminated sites in Japan, determined the concentration of Cu, K, Mg, Al, Ca, Mn, F...
Article
Full-text available
Scopelophila ligulata is an Fe-hyperaccumulator moss growing in acidic environments, but the mechanism of Fe accumulation remains unknown. To understand the mechanism, we determined Fe species in S. ligulata samples. The moss samples were collected from four sites in Japan. The concentrations of Fe, P, S, Cl, and K in them were measured by induced...
Article
Full-text available
Lichen secondary metabolites are known to be associated with heavy metal uptake and tolerance in lichens. Understanding the relationship between their secondary metabolites and heavy metals in them is important for clarifying the mechanisms of their heavy metal accumulation and tolerance. To determine the relationships between the concentrations of...
Article
Understanding the relationship between Cu and Cu-hyperaccumulator lichens is important for their application in monitoring and assessing heavy metal pollution. We investigated the Cu-hyperaccumulator lichen Stereocaulon japonicum at several Cu-polluted and control sites in Japan, and found the lichen to be widely distributed. Its concentrations of...
Article
Phase-separating porous glass (PG) was studied with respect to the ion-exchange reaction of Cs+ ions from aqueous solutions, and the effect of residual sol (aluminosilicate, in particular) in the pores was examined. Cs+ uptake from solutions containing Cs+ ions only was excellent in both the presence and absence of aluminum. For solutions containin...
Article
To understand the ecology and physiology of metal-accumulating lichens growing in Cu-polluted sites, we investigated lichens near temple and shrine buildings with Cu roofs in Japan and found that Stereocaulon japonicum Th. Fr. and Cladonia humilis (With.) J. R. Laundon grow in Cu-polluted sites. Metal concentrations in the lichen samples collected...
Article
We investigated lichen species in the habitats of the copper (Cu)-hyperaccumulating moss Scopelophila cataractae and found that the cup lichens Cladonia subconistea and C. humilis grow on this moss. We performed X-ray fluorescence and inductively coupled plasma mass (ICP-MS) analysis of lichen samples and measured the visible absorption spectra of...
Article
To determine the characteristics of a Cu-hyperaccumulating moss Scopelophilacataractae and the influence of Cu on its structure and on chlorophyll (Chl), we measured reflectance and fluorescence (FL) spectra of S.cataractae samples with different Cu concentrations before and after wetting and the absorption spectra of Chl extracted from these sampl...
Article
To understand the characteristics of a Fe-accumulating moss Scopelophila ligulata, we compared the photoabsorption spectra of pigments from this and several other mosses and found that some of the absorption bands observed only for S. ligulata can be assigned to pheophytin a. The conversion rate from chlorophyll to pheophytin in S. ligulata was cal...
Article
Yttria-stabilized zirconia (YSZ) samples with different Fe concentrations were prepared to study the effects of Fe doping on crystalline and optical properties of YSZ. The former properties were determined by X-ray diffraction, while the latter properties were determined by diffuse reflectance (DR) and photoluminescence (PL) spectroscopies. Lattice...
Article
Photoluminescence (PL) spectra of yttria-stabilized zirconia (YSZ) samples with different Fe mole fractions were measured to study the influence of Fe doping on their spectra. The PL spectra of all the samples can be decomposed into two Gaussian bands centered around 440 and 510nm, and the two bands can be attributed to oxygen vacancy states in the...
Article
The addition of MOx (M: di- or tri-valent transition metal ion) into cerium dioxide (CeO2) enhanced the ability of CeO2 for the oxygen (O2)-releasing reaction at lower temperature and swift hydrogen (H2)-generation reaction. CeO2–MOx (M=Mn, Fe, Ni, Cu) reactive ceramics having high melting points were synthesized with the combustion method from the...
Article
Hollandites crystallize with one-dimensional tunnel-like framework structures. The tunnels in the hollandite are usually occupied by alkaline or alkaline earth elements and a case in point is K2Ga2Sn6O16 (KGSO). This compound has been shown to be catalytically active in the decomposition of endocrine-disrupting chemicals, pentachlorophenol (C6Cl5OH...
Article
The photoluminescence (PL) spectra of two TiO2 powders with different specific surface areas and with additions of 5 wt% Pt were measured. The PL bands around 410 and 800 nm were observed for all the samples. The Pt loading reduced the intensities of the two PL bands and the PL band around 410 nm was blueshifted. We can explain these results by con...
Article
Full-text available
We have investigated the relationship between the structure of the photoluminescence (PL) excitation bands from yttria-stabilized zirconia (YSZ) and the defect states caused by oxygen vacancies in YSZ. The PL excitation spectra of YSZ samples with 2–8mol% Y2O3 concentrations were measured at room temperature, and PL excitation bands from the YSZ sa...
Conference Paper
CeO2 -MOx (M = Mn, Fe, Ni, Cu) reactive ceramics, having high melting points and high conductivities of O2− , were synthesized with the combustion method from their nitrates for solar hydrogen production. The prepared CeO2 -MOx samples were solid solutions between CeO2 and MOx with the fluorite structure through XRD. Two-step water splitting reacti...
Article
By utilization of concentrated solar thermal energy for steam reforming of natural gas, which is an endothermic reaction, the chemical energy of natural gas can be up-graded. The chemical system for steam reforming of natural gas with concentrated solar thermal energy was studied to produce hydrogen by using the thermal storage with molten salt and...
Article
The photoluminescence (PL) and PL excitation spectra of pure and Pt-loaded CeO2 powders were measured, and the PL peaks from the Sm3+ impurity were observed. We found that, as the Pt concentration increases, the peak intensity decreases and the PL excitation band blueshifts. These relationships can be explained by considering electron transfer and...
Article
We have measured photoluminescence (PL) excitation spectra of TiO2 powders with various rutile phase contents, and have found a correlation between the energy level of the PL excitation band (EPLE) and the rutile phase content. The EPLE of the mixture and its band-gap energy were redshifted compared to those expected from its rutile phase content....
Article
Full-text available
Endocrine-disrupting chemicals such as pentachlorophenol (C6Cl5OH) are hazardous for the generative function of living creatures. Photocatalysts give us an effective route for removing these pollutants. Most of the reports are related to a photocatalyst of titanium dioxide (TiO2) fine particles loaded with metal particles such as Pt or Ag. However,...
Article
This study examined a sample-preparation procedure in the glow-discharge mass analysis of yttria-stabilized zirconia (YSZ). We investigated a procedure for mixing it with high-purity gallium to guarantee the electrical conductivity. Several chips of single-crystal specimens were placed in the center of a homemade PTFE mold, embedded with 6 g of mol...
Article
Room temperature photoluminescence (PL) spectra from Tb ions included as unintentional impurities in yttria-stabilized zirconia (YSZ) were measured at various concentrations of Y2O3. Two PL excitation bands were observed from the Tb at around 380 nm for all of the YSZ samples. These two bands can be attributed to the ‐ transition of Tb3+. We found...
Article
The photoluminescence (PL) and PL excitation spectra of the single-crystal samples of yttria-stabilized zirconia (YSZ) were measured. We found that the PL spectra of two samples for the 280-nm excitation significantly differ from one another in intensity, although the two samples have the same macrostructure and the same chemical composition. These...
Article
Full-text available
The influence of platinum loading on the photoluminescence (PL) of the TiO2 by using PL excitation spectra was described. It was found that the Pt loading of TiO2 leads to the blueshift of the PL excitation band. The buleshift can be described as that under UV irradiation, the surface energy level for an electron of the Pt-loaded TiO2 powder was hi...
Article
The photoluminescence (PL) of TiO2 suspensions containing ethanol in the concentration range from 5 to 100 ppm by volume was measured at room temperature. We found that the relationship between the PL of TiO2 in the presence of ethanol and the adsorption of ethanol onto the TiO2 surface can be described as a simple Langmuir isotherm by assuming tha...
Article
We have investigated the photoluminescence (PL) properties of trace amounts of Pr and Tb in single-crystal samples of yttria-stabilized zironia (YSZ), and found that Pr of the order of 10−6 mass% and Tb of the order of 10−5 mass% in YSZ can be detected by the PL spectroscopy. The PL spectra of the YSZ samples for the 280 nm excitation were comprise...
Article
The concentrations of dissolved oxygen (DO) in TiO2 suspensions in the pH range 3-12 were decreased under UV irradiation, although the concentration at pH 1 was unchanged. The decrease in DO concentration was maximized at pH 5. These results suggest that the DO concentration in a solution can be controlled using a TiO2 photocatalyst and UV light. T...
Article
Surface properties and photocatalytic oxidation reactions on the hollandite-type compound K2Ga2Sn6O16 (KGSO) were examined for photoinduced hydrophilicity and oxidative decomposition of an endocrine-disrupting chemical, pentachlorophenol (C6Cl5OH, PCP), under ultraviolet (UV) illumination. The thin films and mesoporous powders of hollandite were us...
Article
Full-text available
A hollandite compound K2Ga2Sn6O16 (KGSO) has photocatalytic activity, although little is known about the optical properties of the compound. To design a higher quality photocatalyst, studies on its optical properties are required. In this study, a KGSO powder and a SnO2 (rutile structure) powder were prepared by the sol–gel method. Photoluminescenc...
Article
We have investigated the photoluminescence (PL) of rutile and anatase TiO2 powders at room temperature in vacuum, in air, and in air with one of C1-C3 alcohols (methanol, ethanol, 1-propanol, and 2-propanol). For rutile TiO2 powder, we observed that the PL intensities in these atmospheres, except air, increase linearly with the square root of the U...
Article
The influence of crystal structure and photocatalytic (PC) reaction on photoluminescence (PL) of several TiO2 powders has been studied at room temperature. The PL intensity of the rutile TiO2 powders increased significantly in proportion to t1/2 by adding ethanol vapor, while those of the anatase TiO2 powders increased slowly. This observation can...
Article
In recent years, extensive studies have been conducted on photocatalysis because of its applicability to treatments of pollutants and to chemical conversion of solar energy. 1 Since many harmful chemicals are decomposed by photocatalytic oxidation, it is important to understand the role of O 2 in the oxidation reaction. But the influences of O 2 ar...

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