Study of ion desorption induced by a resonant core-level excitation of condensed H2O using Auger electron photo-ion coincidence (AEPICO) spectroscopy combined with synchrotron radiation

Ion desorption induced by a resonant excitation of O 1s of condensed amorphous H₂O has been studied by total ion and total electron yield spectroscopy, nonderivative Auger electron spectroscopy (AES) and Auger electron photo-ion coincidence (AEPICO) spectroscopy. The spectrum of total ion yield divided by total electron yield exhibits a characteristic threshold peak at hν = 533.4 eV, which is assigned to the 4a₁ ← O 1s resonant transition. The AES at the 4a₁ ← O 1s resonance is interpreted as being composed of the spectator-AES of the surface H₂O, and the normal-AES of the bulk H₂O, where the 4a₁ electron is delocalized before Auger transitions. H⁺ is found to be the only ion species in AEPICO spectra measured at the 4a₁ ← O 1s resonance and at the O 1s ionization (hν = 560 eV). The electron kinetic energy dependence of the AEPICO yield (AEPICO yield spectrum) at the 4a₁ ← O 1s resonance is found to be greatly different from that at the O 1s ionization. The peak positions of the AEPICO yield spectrum at the 4a₁ ← O 1s resonance are found to correspond to those of the spectator-AES of the surface H₂O, which is extracted from the AES at the 4a₁ ← O 1s resonance. Furthermore, the AEPICO yield is greatly enhanced at the 4a₁ ← O 1s resonance as compared with that at the O 1s ionization. On the basis of these results, a spectator-Auger-stimulated ion desorption mechanism and/or ultra-fast ion desorption mechanism are concluded to be responsible for the H⁺ desorption at the 4a₁ ← O 1s resonance. The enhancement of the H⁺ yield is ascribed to the O---H anti-bonding character of the 4a₁ orbital.     

Study on Chemical Bond and Electronic State of New Gold Mixed Valence Complexes Cs2[AuIX2][AuIIIY4] (X,Y=Cl,Br, I) by Means of 197Au Mössbauer Spectroscopy

Hyperfine Interactions - Cs2[AuIX2][AuIIIX4] (X=Cl, Br, I) is known for a perovskite-type gold mixed-valence system. We have synthesized new gold mixed valence complexes, Cs2[AuIX2][AuIIIY4] (X,...     

The determination of sulfite in a flow injection system with chemiluminescence detection

The emission produced by sulfite on oxidation by permanganate in acidic solution in the presence of riboflavin phosphate or brilliant sulfaflavine is used to determine 0.9–35 ng of sulfite. Only sulfide and thiosulfate also give emissions.     

Nad(p)+-nad(p)h models. 50. Stereo-controlled reduction of methyl 2-oxo-3-methylpentanoate

Racemic and optically active title compound was reduced with chiral and achiral NAD(P)H models. The composition of diastereomers in the product was determined and the steric relationship is discussed.     

The structure of arugomycin,a new anthracycline antibiotic part I. structural elucidation of degradation products,AG1, AG2 and AG3.

Based on ¹H- and ¹³C-NMR and mass spectral analysis and chemical degradation, the structures of degradation products of arugomycin (arugorol, AG1, AG2 and AG3) have been determined as shown in Fig. 1.     

Base-catalyzed homo-brook rearrangement of diastereomeric 7,8- epoxy-7(trimethylsilyl)-6-tridecanols

Semi-quantitative rate measurement of base-catalyzed 1,3-migration of a silyl group from carbon to oxygen (homo-Brook rearrangement) using four diastereomerically pure title compounds revealed that the aptitude for the migration depends markedly on the configurational environment around the trimethylsilyl group of the respective substrate.     

Structure and synthesis of unsaturaded trihydroxy c18 fatty : Acids in rice plants suffering from rice blast disease

Structural elucidation including the absolute configuration was carried out on the trihydroxy C₁₈ -fatty acids isolated from rice plant, Sasanishiki suffered from rice blast disease.     

Measurement of 24-hr whole-body retention of 99mTc-MDP with a thyroid uptake probe (author's transl)

A new method for measurement of 24-hr whole-body retention (WBR) of 99mTc-MDP, using a thyroid uptake probe was established and its clinical significance was evaluated in various bone diseases. (1) Reproducibility of 24-hr WBR in 9 patients was very good. Correlation coefficient was 0.997 and coefficient of variability was only 1.83%. (2) Radiochemical purity of 99mTc-MDP was 97.8 +/- 0.7% (n = 5), indicating no significant inter-lot variations. (3) 24-hr WBR of normal adult males (n = 5) was 30.0 +/- 4.9%, which was significantly elevated compared to the reported 99mTc-HEDP WBR of 19.2 +/- 1.7%. Whole-body retentions of chronic renal failure, metastatic bone disease and hyperthyroidism groups were significantly elevated compared to that of the normal group. However, WBR of steroid-induced osteoporotic group was significantly decreased. Based on these results, this thyroid uptake probe method was simple, reproducible and accurate to measure 24-hr WBR of 99mTc-MDP. Quantification of WBR of 99mTc-MDP was of great clinical value to diagnose metabolic bone disease and to follow-up metabolic and metastatic bone diseases.     

Selective INEPT,a new technique for the 13C NMR assignment of methylene carbons with non-equivalent protons,and its application to the analysis of the 13C NMR spectrum of monensin

A new method based on the combination of selective proton decoupling and INEPT is explained in detail. This technique, named selective INEPT (SEL-INEPT), is a useful and sensitive method for the ¹³C NMR assignment of methylene carbons with non-equivalent protons. The ¹³C NMR spectrum of monensin has been analysed by the application of this technique.