Visualization of Heterogeneous Oxygen Storage Behavior in Platinum‐Supported Cerium‐Zirconium Oxide Three‐Way Catalyst Particles by Hard X‐ray Spectro‐Ptychography

The cerium density and valence in micrometer‐size platinum‐supported cerium–zirconium oxide Pt/Ce₂Zr₂O_x (x=7–8) three‐way catalyst particles were successfully mapped by hard X‐ray spectro‐ptychography (ptychographic‐X‐ray absorption fine structure, XAFS). The analysis of correlation between the Ce density and valence in ptychographic‐XAFS images suggested the existence of several oxidation behaviors in the oxygen storage process in the Ce₂Zr₂O_x particles. Ptychographic‐XAFS will open up the nanoscale chemical imaging and structural analysis of heterogeneous catalysts.     

Study of quantitative evaluation of liver volume and accumulation rate of radioactive agent with single photon emission computed tomography

The quantitative evaluation on measurement of liver volume and the hepatic accumulation rate of the radioactive agent were studied with respect to body constitution, background activity and splenic consumption rate, using single photon emission computed tomography (SPECT). The optical cut-off level for liver volume determination was proved to be reasonable as 35%. The background less than 5% had no influence to their clinical estimation with the error of less than 1.6%. The estimation of liver volume was mostly influenced by the splenic activity. When the splenic activity was increased two times of the hepatic activity, the liver volume was determined as 4.2% larger. Calculated counts by SPECT was well correlated with the hepatic activity. This study proved that SPECT was useful for the quantitative evaluation of the liver volume and the hepatic accumulation rate.     

Chemical trend of Ln-M exchange couplings in heterometallic complexes with Ln = Gd, Tb, Dy, Ho, Er and M = Cu, V

The 4f-3d exchange couplings were definitively and precisely determined in the dinuclear complexes (Ln-M) involving double μ-oxo-bridges, by means of combined high-frequency electron paramagnetic resonance and pulsed-field magnetization techniques, revealing a monotonic decrease of ferromagnetic J(Ln-Cu) in the order of the atomic number, (64)Gd to (68)Er.     

Fast determination of thyroid stimulating hormone in human blood serum without chemical preprocessing by using infrared spectroscopy and least squares support vector machines

The least squares support vector machines (LS-SVM) was used to model infrared spectral data for TSH hormone secreted by thyroid, which regulates the basal metabolic rate. This model was used for direct estimation of the content of TSH in blood serum samples, and the results were comparable with those obtained with the conventional analytical method based on chemoluminescence methodology. Excellent agreement was observed between the conventional method and the newly developed calibration model based in analysis of spectral data with LS-SVM. The latter has clear advantages, because it is fast and requires no reagent once the measurements were done directly in the serum by using a simple mid-infrared spectrometer in the ATR mode. An important advantage observed in this calibration method based on LS-SVM is the remarkable capacity to avoid overfitting in the model-building step, that is, the developed method is highly robust.     

Dehydration reactions in water. Brønsted Acid-surfactant-combined catalyst for ester,ether, thioether,and dithioacetal formation in water

Dehydration reactions in water have been realized by a surfactant-type catalyst, dodecylbenzenesulfonic acid (DBSA). These reactions include dehydrative esterification, etherification, thioetherification, and dithioacetalization. In these reactions, DBSA and substrates form emulsion droplets whose interior is hydrophobic enough to exclude water molecules generated during the reactions. Detailed studies on the esterification revealed that the yields of esters were affected by temperature, amounts of DBSA used, and the substrates. Esters were obtained in high yields for highly hydrophobic substrates. On the basis of the difference in hydrophobicity of the substrates, unique selective esterification and etherification in water were attained. Furthermore, chemospecific, three-component reactions under DBSA-catalyzed conditions were also found to proceed smoothly. This work not only may lead to environmentally benign systems but also will provide a new aspect of organic chemistry in water.     

Oxygenation and chlorination of aromatic hydrocarbons with hydrochloric acid photosensitized by 9-mesityl-10-methylacridinium under visible light irradiation

Efficient photocatalytic oxygenation of toluene occurs under visible light irradiation of 9-mesityl-10-methylacridinium (Acr⁺–Mes) in oxygen-saturated acetonitrile containing toluene and aqueous hydrochloric acid with a xenon lamp for 15 h. The oxygenated products, benzoic acid (70 %) and benzaldehyde (30 %), were formed after the photoirradiation. The photocatalytic reaction is initiated by intramolecular photoinduced electron transfer from the mesitylene moiety to the singlet excited state of the Acr⁺ moiety of Acr⁺–Mes, which affords the electron-transfer state, Acr^?–Mes^?+. The Mes^?+ moiety can oxidize chloride ion (Cl^?) by electron transfer to produce chlorine radical (Cl^?), whereas the Acr^? moiety can reduce O₂ to O ₂ ^?? . The Cl^? radical produced abstracts a hydrogen from toluene to afford benzyl radical in competition with the bimolecular radical coupling of Cl^?. The benzyl radical reacts with O₂ rapidly to afford the peroxyl radical, leading to the oxygenated product, benzaldehyde. Benzaldehyde is readily further photooxygenated to yield benzoic acid with Acr^?–Mes^?+. In the case of an aromatic compound with electron-donating substituents, 1,3,5-trimethoxybenzene, photocatalytic chlorination occurred efficiently under the same photoirradiation conditions to yield a monochloro-substituted compound, 2,4,6-trimethoxychlorobenzene.     

In situ FTIR studies of primary intermediates of photocatalytic reactions on nanocrystalline TiO2 films in contact with aqueous solutions

Multiple internal reflection infrared spectroscopy was applied to in situ investigations of surface intermediates of photocatalytic reactions on nanocrystalline TiO(2) films in contact with aqueous solutions. UV irradiation in the presence of dissolved O(2) caused the appearance of new bands peaked at 943, 838, and 1250-1120 cm(-)(1) together with intensity changes in other bands. Investigations of influences of the solution pH, the presence or absence of hole and electron scavengers, and isotopic H(2)O --> D(2)O exchange on the spectral changes have revealed that the primary step of photocatalytic O(2) reduction is the formation of the surface peroxo species, Ti(O(2)), giving the 943 cm(-)(1) band, probably with the surface superoxo species, TiOO., as a precursor, in neutral and acidic solutions. The surface peroxo species is then transformed to the surface hydroperoxo, TiOOH, giving the 838 and 1250-1120 cm(-)(1) bands, by protonation in the dark. This is, to our knowledge, the first direct in situ spectroscopic detection of primary intermediates for the photocatalytic O(2) reduction in aqueous solutions. On the basis of the assignment, a possible reaction scheme for various processes of the photocatalytic O(2) reduction is proposed, which is in harmony with other spectral changes induced by the UV irradiation.     

Role of electron-transfer processes in reactions of diarylcarbenium ions and related quinone methides with nucleophiles

Second-harmonic alternating current voltammetry has been used to determine one-electron reduction potentials of 15 diarylcarbenium ions and 5 structurally analogous quinone methides, which have been employed as reference electrophiles for the development of nucleophilicity scales. A linear correlation (r(2) = 0.993) between the empirical electrophilicity parameters E and the reduction potentials in acetonitrile (E = 14.091E degrees (red) - 0.279) covering a range of 1.64 V (or 158 kJ mol(-)(1)) has been observed. For a large number of nucleophiles, it has been demonstrated that the observed activation free energies of the electrophile-nucleophile combinations are 61-195 kJ mol(-)(1) smaller than the free energy change of electron transfer from nucleophile to electrophile, which definitely excludes outer-sphere electron transfer occurring during these reactions.