Atomic motion of guest atoms inside semiconducting clathrate cages is considered as an important source for the glasslike thermal behavior. 69 Ga and 71 Ga Nuclear Magnetic Resonance (NMR) studies on type-I Ba8Ga16Sn30 show a clear low temperature relaxation peak attributed to the influence of Ba rattling dynamics on the framework-atom resonance, with a quadrupolar relaxation mechanism as the leading contribution. The data are analyzed using a two-phonon Raman process, according to a recent theory involving localized anharmonic oscillators. Excellent agreement is obtained using this model, with the parameters corresponding to a uniform array of localized oscillators with very large anharmonicity.
We have synthesized type-VIII and type-I Ba8Ga16Sn30 clathrates by using different annealing treatments, confirmed with XRD and electron microprobe measurements. NMR lineshape measurements identified a broad resonance corresponding to first-order-shifted satellites. Simulations for the type I structure based on first principles calculations provided an excellent fit to the data, with the best agreement provided by the calculated lowest-energy configuration, having no Ga-Ga bonds. These results allow us to address local configurations within the random type-I alloy, as well as atomic displacements and bond-length distributions, which we compare to experiment.
Background: To introduce a modified pleurodesis as an effective treatment for refractory chylothorax and to develop a novel insight for its mechanism.Methods: Patients who underwent thoracic surgery at West China Hospital or its affiliated hospitals between 2010 and 2015 and who subsequently experienced chylothorax that was not resolved by conventional treatment, received daily pleurodesis involving 100 mL 50% glucose and 20 mL 1% lidocaine. The chest tube was clamped after 7 days of pleurodesis, regardless of drainage amount. If no remarkable pulmonary atelectasis was detected within 2 days, the chest tube was removed. All patients were followed up with for at least 3 months after discharge from our hospital.Results: Among the 34 patients, 10 did not experience an increase in the pleural fluid after the chest tube was clamped. Minor effusion increase occurred in 21 patients, while encapsulated effusion occurred in 3. In 23 patients among the latter 24 patients, pleural fluid was gradually absorbed and disappeared spontaneously.One patient suffered chylothorax recurrence after discharge but successfully recovered after the second round of modified pleurodesis. Several patients suffered from electrolyte imbalance, weakness, and dyspnea; all were cured by plasma infusion and other symptomatic treatments.Conclusions: Being safe and effective for patients with postoperative refractory chylothorax, our modified pleurodesis enhanced the process of chemical pleurodesis and could remove the chest tube right after the extensive adhesion formed instead requiring a wait for drainage decrease. This method can thus shorten the period of hospitalization and reduce fluid loss compared with traditional pleurodesis.
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