1,761 research outputs found

    Theoretical study on isomerization of α-acids: A DFT calculation

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    The α-acids contained in hops are one of the ingredients of beer. The isomerization of α-acids produces iso-α-acids, the main source of bitterness in beer. In this study, the isomerization mechanism of the α-acid, cohumulone, was elucidated by using density functional theory in conjunction with the polarizable continuum model or 3D-RISM integral equation theory of liquids. The calculated reaction diagram is consistent with experimental results; the activation free energy difference between the cis and trans isomers is in good agreement with the experimental estimate. The activation energy difference results from solvation energy. Additionally, a calculation of NMR chemical shifts showed that the proton position of isocohumulone is different from that proposed previously. The effect of Mg²⁺ cation on the isomerization was also investigated. Both the activation and reaction free energy are stabilized by the presence of Mg²⁺, which is consistent with experimental results. Water solvation reduces the activation free energy

    Local SiC photoluminescence evidence of non-mutualistic hot spot formation and sub-THz coherent emission from a rectangular Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta} mesa

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    From the photoluminescence of SiC microcrystals uniformly covering a rectangular mesa of the high transition temperature TcT_c superconductor Bi2_2Sr2_2CaCu2_2O8+δ_{8+\delta}, the local surface temperature T(r)T({\bm r}) was directly measured during simultaneous sub-THz emission from the N103N\sim10^3 intrinsic Josephson junctions (IJJs) in the mesa. At high bias currents II and low bath temperatures Tbath 35T_{\rm bath}\lesssim~35 K, the center of a large elliptical hot spot with T(r)>TcT({\bm r})> T_c jumps dramatically with little current-voltage characteristic changes. The hot spot doesn't alter the ubiquitous primary and secondary emission conditions: the ac Josephson relation and the electromagnetic cavity resonance excitation, respectively. Since the intense sub-THz emission was observed for high Tbath 50T_{\rm bath}\gtrsim~50 K in the low II bias regime where hot spots are absent, hot spots can not provide the primary mechanisms for increasing the output power, the tunability, or for promoting the synchronization of the NN IJJs for the sub-THz emission, but can at best coexist non-mutualistically with the emission. No T(r)T({\bm r}) standing waves were observed

    Hautgeschwulste durch Lungendistoma (Paragonimus westermani)

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    Zwei 7 jahrige Kinder nahmen ungekochte Flussigkeit von Potamon dehaanii zu sich, eine Volksrnedizin gegen Keuchhusten. Einige Monate darauf bemerkten sie blutige Sputa und nicht entzundliche Geschwulste an den Lenden oder der Bauchseite. In den Tumoren wurde je ein Lungendistoma entdeckt. Dieser Parasit kann daher manchmal in die Subkutis oder in die tiefe Kutisschicht einwandern. Zum Schlusse Inochten wir Herrn Prof. Tanabe vom pathologischen Institut dieser Universitat unsern warmsten Dank aussprechen dafur, dass er die Struktur der Parasiten eingehend untersuchte. </p

    Treatment of mandibular condyalr osteochondroma

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    We successfully treated a case of facial asymmetry involved in unilateral mandibular condylar osteochondroma with ipsilateral mandibular condylectomy and contralateral ramus osteotomy. A female, 32-year 11-month of age, had a chief complaint of facial asymmetry which initiated about 10 years ago. A mirror image analysis using a non-contact 3D image scanner revealed that the soft tissue on the deviated side was protruded more than 5.50 mm compared with the non-deviated side. The patinet was diagnosed as facial asymmetry with a skeletal Class III jaw-base relationship caused by unilateral mandibular condylar osteochondroma. After 18 months of preoperative orthodontic treatment, ipsilateral condylectomy and contralateral sagittal split ramus osteotomy were performed. As the results of postoperative orthodontic treatment for 20 months, an ideal occlusion having a Class I molar relationship with an adequate interincisal relationship was achieved. Facial asymmetry and mandibular protrusion were dramatically improved, and the differences between the deviation and non-deviation sides were decreased to less than 1.11 mm. The acceptable occlusion and symmetric face were maintained throughout 1-year retention period. Conclusively, our results indicated the stability after condylectomy without condylar reconstruction in a patient with unilateral condylar osteochondroma
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