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Several potassium selenocarboxylates were synthesized in moderate to good yields by the direct reaction of acyl chlorides with potassium selenide. The potassium salts were readily oxidized with XeF2 to give diacyl diselenides in quantitative yields. The structure of di(4‐methoxybenzoyl) diselenide was established by X‐ray diffraction analysis. Intramolecular interactions between the carbonyl oxygen and the selenium that is connected to the opposite carbonyl group were observed. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 373–379, 1999 相似文献
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996.
Petko St. Petkov Kristina Simeonova Iskra Z. Koleva Hristiyan A. Aleksandrov Yoshihiro Kubota Satoshi Inagaki Valentin Valtchev Georgi N. Vayssilov 《Molecules (Basel, Switzerland)》2021,26(23)
We used computational modeling, based on Density Functional Theory, to help understand the preference for the formation of silanol nests and the substitution of Si by Ti or Al in different crystallographic positions of the MSE-type framework. All these processes were found to be energetically favorable by more than 100 kJ/mol. We suggested an approach for experimental identification of the T atom position in Ti-MCM-68 zeolite via simulation of infrared spectra of pyridine and acetonitrile adsorption at Ti. The modeling of adsorption of hydrogen peroxide at Ti center in the framework has shown that the molecular adsorption was preferred over the dissociative adsorption by 20 to 40 kJ/mol in the presence or absence of neighboring T-atom vacancy, respectively. 相似文献
997.
Yuki?KanazawaEmail authorView authors OrcID profile Tetsuya?Yamada Aki?Kido Koji?Fujimoto Kyoko?Takakura Hiroaki?Hayashi Yasutaka?Fushimi Satoshi?Kozawa Koji?Koizumi Makiko?Okuni Naomi?Ueda Kaori?Togashi 《Applied magnetic resonance》2017,48(2):125-134
To visualize the condition of impregnation of polyethylene glycol (PEG) in waterlogged wood, we demonstrated magnetic transfer (MT) magnetic resonance imaging (MRI) through a series of process of PEG impregnation. Three different samples were examined; reference wood, 10 cm cut wood, and 5 cm cut wood. During this study, the upper section sample was kept immersed in water, for the middle and lower sections the concentration of PEG solution was changed at 20 wt% intervals from 20 to 100 wt%. The impregnated periods of each PEG solution concentration were 14 days. Then, MR imaging were performed with/without MT pulse. The MTR value for both 10 cm- and 5 cm-samples were shown to decrease at 20 wt% PEG at peak concentration. When the sample volume was large, e.g., 10 cm-sample, the MTR value decreased to 100 wt% PEG concentration. In contrast, when a sample volume was small, e.g., 5 cm-sample, MTR value decreased to 60 wt% PEG concentration. In conclusion, MTR analysis makes it possible to nondestructively visualize and evaluate the inner condition concerning the PEG impregnation method for waterlogged wood. 相似文献
998.
Epitaxial Sb-doped SnO2 (0 0 1) thin film on a TiO2 (0 0 1) substrate was successfully prepared by laser-assisted metal organic deposition at room temperature. The effects of the precursor thin film and laser fluence on the resistivity, carrier concentration, and mobility of the Sb-doped SnO2 film were investigated. The resistivity of the Sb-doped SnO2 film prepared by direct irradiation to metal organic film is one order of magnitude lower than that of film prepared by irradiation to amorphous Sb-doped SnO2 film. From an analysis of Hall measurements, the difference between the resistivity of the Sb-doped SnO2 film prepared using the metal organic precursor film and that of amorphous precursor film appears to be caused by the mobility. Direct conversion of the metal organic compound by excimer laser irradiation was found to be effective for preparing epitaxial Sb-doped SnO2 film with low resistivity. 相似文献
999.
Satoshi Goshima Masayuki Kanematsu Hiroshi Kondo Yusuke Tsuge Haruo Watanabe Yoshimune Shiratori Minoru Onozuka Noriyuki Moriyama 《Magnetic resonance imaging》2009,27(9):1230-1235
The purpose of this study was to compare observer interpreted steady-state coherent coronal images and gadolinium-enhanced axial images in terms of the detection and grading of esophageal varices. Magnetic resonance imaging (MRI) and gastrointestinal endoscopy were performed within 2 weeks in 90 patients with chronic liver damage, including 55 with untreated esophageal varices, for periodic screening purposes. Two blinded readers retrospectively reviewed T1- and T2-weighted images with gadolinium-enhanced (gadolinium image set) and steady-state coherent (coherent image set) images. Sensitivity for the detection of esophageal varices was higher (P<.001) in the gadolinium image set (76%) than in the coherent image set (35%); on the other hand, specificity was higher (P<.001) in the coherent image set (91%) than in the gadolinium image set (66%). Furthermore, area under the ROC curve was higher for the gadolinium image set (Az=0.823) than the coherent image set (Az=0.761) (P=.48). Moderate and weak positive correlations with endoscopic grades were found for the gadolinium image (r=0.48, P<.01) and coherent image sets (r=0.34, P=.018). The addition of steady-state coherent imaging to the current routine liver imaging protocol did not improve the detection or grading of esophageal varices, whereas gadolinium-enhanced imaging was found to be potentially valuable. Nevertheless, endoscopy was confirmed to be mandatory in patients with esophageal varices suspected by MRI of the liver. 相似文献
1000.
Yohei Noda Takayuki Kumada Takeji Hashimoto Satoshi Koizumi 《Physica B: Condensed Matter》2009,404(17):2572-2574
We carried out a small-angle neutron scattering (SANS) study of dynamically polarized polyethylene (PE) samples doped with 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). The transmission of the PE with almost fully polarized neutrons (98.5%) increased with increasing the proton polarization, P. The incoherent scattering cross section decreased with increasing P. The effect of P on the polarized neutrons’ transmission and the incoherent scattering cross section agreed well with the theory. The q-dependence of the coherent scattering, which reflects a two-phase structure of PE composed of crystalline and amorphous domains, was kept unchanged by the proton polarization, but the intensity increased by a factor of 3 and 6 for P=+23% and −23%, respectively. The results mean that the contrast between the two phases was successfully enhanced by a dynamic nuclear polarization (DNP) technique. However, the enhancement is only 1/13–1/16 of the enhancement calculated by assuming a homogeneous polarization through the PE sample. The discrepancy suggests that P in amorphous domains (25%) should be higher than that in crystalline domains (22%) by 3%, which in turn may suggest the partial depolarization of proton spins on the way of the spin diffusion from amorphous domains, where TEMPO radicals localize, to crystalline domains. 相似文献