Aggregate domain growth of gold nanoparticle on chemically modified glass surface.

The aggregation of Au nanoparticle (AuNP) on a glass surface functionalized with 3-aminopropyltrimethoxysilane (APTMS) was studied by means of UV-vis spectroscopy and AFM measurements. The optical response of AuNP due to localized surface plasmon resonance (LSPR) was increased with the increment of AuNP amount on the functionalized glass surface, then the changes of spectral shape corresponds to the aggregate formation was finally observed. The AFM image shows in homogeneous aggregation of nanoparticles on the substrate surface. Three-dimensional aggregate growth was observed.

Self-catalytic degradation of ortho-chlorophenol with Fenton's reagent studied by chemiluminescence.

The degradation of ortho-chlorophenol using Fenton's reagent was studied by chemiluminescence (CL). Without a special CL reagent, a weak CL emission from the mixture of ferrous ion and hydrogen peroxide was observed at room temperature. The CL intensity was increased by the addition of ortho-chlorophenol into the mixed solution. When the temperature was raised to 65 degrees C, the CL intensity was enhanced strongly. The CL mechanisms for the system H2O2-Fe2+ with and without ortho-chlorophenol were studied by examining the CL spectrum, gas chromatography-mass spectrometry and electron spin resonance spectrum. The effects of various free radical scavengers, surfactants and fluorescence compounds on the CL intensity were also investigated. A self-catalytic oxidation mechanism was proposed. The results showed that singlet oxygen was the main emitter for the system H2O2-Fe2+. The strong CL from the system H2O2-Fe(2+)-ortho-chlorophenol was due to singlet oxygen and electronically excited quinone. The benzenediol-like intermediate product formed during the phenol oxidation process greatly promoted the Fenton's reaction and led to higher CL intensity. Chemiluninescence is a novel approach for the investigation of the oxidation of some organic pollutants by Fenton's reagent.

Enhanced chemiluminescence of peroxomonosulfate-cobalt (II) system in the presence of dicarboxylic acids.

In the present work, the effects of molecular mass aliphatic dicarboxylic acids on the HSO(5)(-)-Co(2+) chemiluminescence (CL) system were investigated. It was found that the aliphatic dicarboxylic acids could enhance the CL of the HSO(5)(-)-Co(2+) system. Moreover, the CL intensities improved regularly with increasing carbon chain length of the dicarboxylic acids. To investigate the CL enhancement mechanism, dynamic profiles, CL spectroscopy, ESR spectrum and the effects of various free radical scavengers on the CL system were employed. The results indicated that the enhancement of the CL should be attributed to the formation of peroxo-diacid, which finally decomposed to the original dicarboxylic acid and singlet oxygen. The mechanism of the HSO(5)(-)-Co(2+)-dicarboxylic acid CL system was then proposed.

Simultaneous extraction of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar polychlorinated biphenyls from contaminated soil using pressurized liquid extraction.

Pressurized liquid extraction (PLE) was studied for simultaneous extractions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/PCDFs), and of coplanar polychlorinated biphenyls (Co-PCBs) from a tightly bounded condition in the soil matrix. Temperatures were maintained at 175 and 200 degrees C, respectively, and two or three static cycles for single PLE with toluene and acetone/n-hexane were studied using a certified reference material to compare the effects of those conditions on recoveries. A single PLE with two static cycles at 150 degrees C and the repeated single PLE (additional PLE) were reference methods. Satisfactory recoveries were not obtained using tested single PLE (2,3,7,8-substituted PCDD/PCDFs and Co-PCBs average, average (avg.) 79-103%), but they were achieved using additional PLE (acetone/n-hexane, avg. 115-128%; toluene, avg. 111-132%). In addition, these methods and additional PLE of the reference method using acetone/n-hexane were not markedly different (avg. 123-128%). That fact suggests that the use of mixed solvents and additional PLE were more important factors than temperatures and static cycles of single PLE for quantitative and simultaneous extractions of those compounds from the soil.

Polychlorinated dibenzo-p-dioxins and dibenzofurans in paddy soils and river sediments in Akita, Japan.

Paddy soils and sediments from the Yoneshirogawa, Omonogawa, and Koyoshigawa River Basins in Akita were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs). The levels and compositions in those samples including soils from non-agricultural areas (non-agricultural soils) were investigated using isomer-specific analysis to determine characteristic sources. The PCDD/PCDF compositions in the samples were compared with respect to possible sources. The PCDD/PCDF concentrations in paddy soils were much higher than those in the non-agricultural soils and much higher than those found in other parts of Japan. Although PCDD/PCDFs were ubiquitous in sediments from river sources to mouths of the respective river basins, those concentrations were much lower than those from paddy soils and non-agricultural soils, and from other parts of Japan. Comparison of PCDD/PCDF homologues and isomer compositions for samples indicated that compositions of paddy soils and sediments, except for those from river sources, had similar characteristics to PCDD/PCDFs originating from impurities in herbicides, 2,4,6-trichlorophenyl 4-nitrophenyl ether (CNP) and pentachlorophenol (PCP), and that compositions of river-source sediments and non-agricultural soils resembled those of atmospheric depositions. Results of statistical analyses suggest that PCDD/PCDF contamination of paddy soils and sediments is attributable mainly to three sources: CNP, PCP, and atmospheric deposition. Results of this study also demonstrate that CNP and PCP are not only important contaminants of local areas of Japan, but that they exist throughout Akita, in northern Japan. We therefore conclude that PCDD/PCDF pollution caused by those compounds has a widespread influence on paddy soils and river sediments in Japan.

Application of a pH Electrode Incorporating an Ionic Liquid Salt Bridge to the Measurement of Rainwater Samples.

A pH electrode incorporating a reference electrode different from that in conventional electrodes was applied to the measurement of rainwater pH. The reference electrode utilizes a recently proposed ionic liquid salt bridge instead of a conventional potassium chloride salt bridge. The response time of this electrode was remarkably improved in rain sample pH measurements compared to that of conventional pH electrodes. In addition, the measured pH values of rain samples seemed to be more accurate with this electrode.

Ligand Exchange Reactions of a Monomeric Zirconium Carbonate Complex with Carboxylic Acids Studied by Extended X-ray Absorption Fine Structure, UV Absorption and Raman Spectrophotometry.

Ligand exchange reactions of a monomeric zirconium carbonate complex with carboxylic acids were studied by means of extended X-ray absorption fine structure (EXAFS), UV absorption spectrophotometry and Raman spectrometry. Three carboxylic acids, gluconic acid, and L-tartaric acid and citric acid, which are mono-, di- and tri-carboxylic acids, respectively, were employed in this study. These three carboxylic acids gave different spectral signatures and concentration dependences, respectively. In the gluconic acid system, the peaks on Fourier transform of EXAFS spectrum and Raman spectrum caused by carbonate ion coordinating to zirconium atom were obviously decreased with increasing gluconic acid concentration compared to the other two carboxylic acid systems. This indicates the high association ability of gluconic acid to zirconium, which was revealed by UV spectrophotometric analysis.

Pressurized liquid extraction of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar polychlorinated biphenyls from contaminated soil.

Extraction solvents for pressurized liquid extraction (PLE) used to extract polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs) from contaminated soil were investigated. The PCDD/PCDFs and Co-PCBs in Certified Reference Material: CRM 0422 (Forest soil) were extracted using toluene, n-hexane, acetone, acetone/toluene and acetone/n-hexane (1:1, v/v). Soxhlet extraction was the reference method. Results demonstrated that PLE using mixed solvents produced better analyte recoveries than the single solvents. However, these results were lower than those for Soxhlet extraction. Additional extraction cycles using mixed solvents achieved better recovery results. Mixed solvents and several extraction cycles were necessary for satisfactory extraction of more tightly bound PCDD/PCDFs and Co-PCBs from soil.

Discrimination of ionic pollutants except condensation nuclei of acid fog using an ultrasonic humidifier.

Fog droplets in the atmosphere are first produced by the activation of cloud condensation nuclei (CCN), which are originally some ionic compound. Subsequently, the nuclei grow by vapor diffusion. Fog droplets are polluted through the activation process and successive diffusion growth and residence (post activation). We cannot distinguish the effects of the two pollution processes of natural fog water samples. We found that fog droplets can be produced artificially without CCN using an ultrasonic humidifier. Because the artificial fog droplets are not polluted by CCN, the movement of the fog droplets in natural air will take up some pollutants in the air. Consequently, the two pollution processes of fog (the activation of CCN and the post activation process) can be discriminated using data from field experiments. This sampling analytical method is extremely important for further research regarding fog, clouds and environmental chemistry.

A monomeric [Zr(CO3)4](4-) complex in an ammonium zirconium carbonate aqueous solution studied by extended X-ray absorption fine structure, Raman and nuclear magnetic resonance spectroscopy.

The speciation of zirconium complexes in ammonium zirconium carbonate (AZC) solutions should be further studied in order to develop high-performance AZC complexes for use in elaborate industrial materials. Thus, the speciation and the structure of various zirconium species in ammonium zirconium carbonate solutions were investigated over a wide range of total carbonate and ammonium concentrations. By employing extended X-ray absorption fine structure analysis, and Raman and (13)C NMR spectroscopy, it was found that four carbonate ions coordinate bidentately to the zirconium ion. In addition, the exact concentration ranges of carbonate and ammonium in AZC necessary to generate the monomeric zirconium carbonate complex [Zr(CO3)4](4-) were determined.

Geranylgeranylacetone selectively binds to the HSP70 of Helicobacter pylori and alters its coccoid morphology.

Geranylgeranylacetone (GGA) is used to treat patients suffering from peptic ulcers and gastritis. We examined the effect of GGA on Helicobacter pylori, which is a causative factor of gastrointestinal diseases. Previously, we have reported that GGA binds specifically to the molecular chaperone HSP70. In this paper, we report that GGA bounds to H. pylori HSP70 (product of the DnaK gene) with 26-times higher affinity than to human HSP70, and induced large conformational changes as observed from surface plasmon resonance and circular dichroism. Binding of GGA suppressed the activity of the H. pylori chaperone. GGA also altered several characteristics of H. pylori cells. GGA-treated cells elicited enhanced interleukin-8 production by gastric cancer cell lines and potentiated susceptibility to complement as compared to untreated cells. GGA also caused morphological alterations in H. pylori as reflected in fewer coccoid-like cells, suggesting that GGA converts H. pylori to an actively dividing, spiral state (vegetative form) from a non-growing, coccoid state. This morphological conversion by GGA resulted in accelerated growth of H. pylori. These results suggest a model in which GGA sensitizes H. pylori to antibiotic treatment by converting the cells to an actively growing state.

Interfacial adsorption state of protonated lipophilic porphyrins in a liquid-liquid system by using reflection spectrometry.

Analysis by reflection spectrometry was performed to clarify the interfacial adsorption of protonated lipophilic tetraphenylporphyrin derivatives in a dodecane-aqueous sulfuric acid system, and to confirm the utility of partial reflection spectroscopy. Interfacial adsorption was not observed for porphyrins substituted at the 2,6 positions of meso-phenyl groups, suggesting that the substituents prevent porphyrins from forming aggregates by steric hindrance. Polymorphous J-aggregates of acid dications were produced by tetra-p-tolylporphyrin with a saturated interfacial molecular density of 1.0 x 10(-10) mol cm(-2), which could yield 48 degrees as a mean tilting angle of the pyrrole ring plane from the interface normal. Partial-reflection spectrometry can provide sensitive detection and molecular orientation analysis of interfacial adsorbates.

Canonical discriminant analysis of cadmium content levels in unpolished rice using a portable near-infrared spectrometer.

Near-infrared analysis (NIRA) was applied to discriminate and determine the cadmium content levels of unpolished rice using canonical discriminant analysis (CDA). The overall correct classification rate was 85.2% for 318 NIR spectra, repeated three times for 106 samples. After a further improvement through decreased misclassification rates, NIRA could be useful as a rapid, nondestructive and convenient analytical method for primary screening and detecting of cadmium-polluted rice.

Effect of long-range transport of air mass on the ionic components in radiation fog in northern Japan.

Water samples from radiation and upslope types of fog were collected at Takanosu Basin and Hachimantai mountain range of Akita Prefecture in northern Japan, respectively. The effect of the long-range transport of pollutants from the Asian Continent to the basin and the mountain range on the chemical characteristics of two types of fog was studied using chemical analysis data for the water samples as well as the back-trajectories of the air mass. In particular, non-sea-salt (nss)-SO4(2-) of radiation fog provided a much higher concentration than that of upslope fog, which suggests that nss-SO4(2-) might be transported mainly from the Asian Continent. The transport and uptake mechanism of pollutants in the radiation fog water were explained based on their accumulation in the basin due to anticyclonic subsidence and by the long-lasting fog behavior.

A near infrared spectroscopic discrimination of noodle flours using a principal-component analysis coupled with chemical information.

Using a portable near infrared (NIR) spectrometer, we discriminated flours for making Japanese noodles (Soba), not only relying on a statistical and mathematical approach, but also on a chemical interpretation of the NIR spectra. In original NIR spectra, the particle-size difference, which results in an undesired systematic variation, was extracted and interpreted as the first-principal component factor by a principal-component analysis. The discrimination of flour materials cannot be satisfied by this factor. However, after a standardized treatment for the original spectra, the particle-size effects were eliminated; alternatively, differences in the chemical contents were extracted as principal-component factors. Using these factors, flour material discrimination was achieved much better. This study suggests a novel idea of utilizing the wavelength contribution ratio spectra for interpreting the factors extracted from the principal-component analysis for the NIR spectra. This report also describes the relationship between the NIR spectra and the chemical-analysis data.

Carbon nanodots sensitized chemiluminescence on peroxomonosulfate-sulfite-hydrochloric acid system and its analytical applications.

In the present work, new water-soluble fluorescent carbon nanodots (C-dots) were prepared in a facile microwave pyrolysis approach in minutes by combining glycine and polyethylene glycol 200 (PEG 200). Transmission electron microscopy (TEM) measurements showed that the resulting C-dots had diameters of about 3 nm. (13)C NMR spectra further confirmed the presence of carbons (sp(2) and sp(3)) indicating a nanocrystalline core of the resulting C-dots with hydroxyl of PEG 200 covered outside. It was discovered that the prepared C-dots could dramatically enhance the chemiluminescence (CL) intensity of potassium peroxomonosulfate-sodium sulfite-hydrochloric acid (PSHA) reactions. UV-vis absorption and photoluminescence (PL) spectra indicated that the C-dots sensitized enhancements originated from their energy transfer and electron-transfer annihilation effects on the CL system. When the concentration of C-dots was 4×10(-5) M, and those of KHSO(5), Na(2)SO(3) and HCl were 1×10(-2) M, an excellent performance was obtained. The C-dots sensitized CL system was successfully applied to the determination of aliphatic primary amines in real water samples with satisfactory results.

Gentamicin inhibits HSP70-assisted protein folding by interfering with substrate recognition.

We previously reported that gentamicin (GM) specifically binds to heat-shock protein with subunit molecular masses of 70 kDa (HSP70). In the present study, we have investigated the effects of GM binding on HSP70-assisted protein folding in vitro. The C-terminal, and not the N-terminal of HSP70 was found to bind to GM. GM significantly suppressed refolding of firefly luciferase in the presence of HSP70 and HSP40, although the ATPase activity of HSP70 was unaffected by GM. A surface plasmon resonance analysis revealed that GM specifically interferes with the binding of HSP70 to a model peptide that mimics the exposed hydrophobic surface of the folding intermediates. These results indicated that GM inhibits the chaperone activity of HSP70 and may suppress protein folding via inhibition of HSP70 in vivo.

Gold nanoparticle monolayer formation on a chemically modified glass surface.

Physicochemical analyses of Au nanoparticle monolayer formation on a glass surface functionalized with 3-aminopropyltrimethoxysilane (APTMS) and ethyltrimethoxysilane (ETMS) were performed for fabricating a nanoarchitecture of metal nanoparticles using self-assembly. The Au nanoparticle surface density on the functionalized glass surface correlated linearly with the optical response because of Au-nanoparticle localized surface plasmon resonance (LSPR). This relation enabled assessment of the Au nanoparticle deposition. A Frumkin isotherm showed the deposition of Au nanoparticles on the APTMS or APTMS/ETMS functionalized glass surface. For an APTMS-derivatized surface, the affinity between the Au nanoparticles and the surface decreased with the lowering of the APTMS surface coverage. The interaction parameter exhibited attractive interaction of 30-nm-diameter Au nanoparticles; 12 nm particles were repulsive. Adsorption isotherm experiments using Au nanoparticles on glass surfaces with an APTMS and ETMS mixed layer suggest that hydrophobic interaction between Au nanoparticles' bare gold surfaces caused the attractive interaction among 30-nm-diameter nanoparticles.

Measurement of antibody binding to protein immobilized on gold nanoparticles by localized surface plasmon spectroscopy.

Antibody binding to bovine serum albumin (BSA) and human serum albumin (HSA) immobilized onto gold nanoparticles was studied by means of localized surface plasmon resonance (LSPR) spectroscopy. Amine-modified glass was prepared by self-assembly of amine-terminated silane on substrate, and gold (Au) nanoparticles were deposited on the amine-modified glass substrate. Au nanoparticles deposited on the glass surface were functionalized by BSA and HSA. BSA immobilization was confirmed by LSPR spectroscopy in conjunction with surface-enhanced Raman scattering spectroscopy. Then, LSPR response attributable to the binding of anti-BSA and anti-HSA to BSA- and HSA-functionalized Au nanoparticles, respectively, was examined. Anti-HSA at levels larger than approximately 10 nM could be detected by HSA-immobilized chips with LSPR optical response, which was saturated at concentrations greater than approximately 650 nM of anti-HSA.

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry.

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.