110-GHz, 50%-efficiency mushroom-mesa waveguide p-i-n photodiodefor a 1.55-μm wavelength

A mushroom-mesa structure is proposed to reduce the CR-time constant which originates from the waveguide photodiode structure. Experimental results at a 1.55-μm wavelength show that the multimode waveguide p-i-n photodiode with mushroom-mesa structure has an electrical 3-dB bandwidth of more than 75 GHz in the frequency domain and an electrical 3-dB bandwidth of 110 GHz in the time domain. The external quantum efficiency is 50% or 0.63 A/W, which leads to a record bandwidth-efficiency product of 55 GHz for long wavelength p-i-n photodetectors     

Lymphangioma of the esophagus presenting symptoms of achalasia--a case report

A case of lymphangioma of the esophagus with symptoms of achalasia was presented. Compressible and folded intramural tumors were found from the middle to the lower part of the esophagus and the Mecholyl test was positive. After incisional biopsy at lower esophagus through full thickness of the wall, the opening was repaired with Thal-Hatafuku's fundic patch procedures to relieve achalasia. Postoperative course was uneventful and symptoms of achalasia completely disappeared.     

Small-angle neutron scattering study of specific interaction and coordination structure formed by mono-acetyl-substituted dibenzo-20-crown-6-ether and cesium ions

This study uses small-angle neutron scattering (SANS) to elucidate the coordination structure of the complex of mono-acetyl-substituted dibenzo-20-crown-6-ether (ace-DB20C6) with cesium ions (Cs⁺). SANS profiles obtained for the complex of ace-DB20C6 and Cs⁺ (ace-DB20C6/Cs) in deuterated dimethyl sulfoxide indicated that Cs⁺ coordination resulted in a more compact structure than the free ace-DB20C6. The data were fitted well with SANS profiles calculated using Debye function for scattering on an absolute scattering intensity scale. For this theoretical calculation of the scattering profiles, the coordination structure proposed based on density functional theory calculation was used. Consequently, we conclude that the SANS analysis experimentally supports the proposed coordination structure of ace-DB20C6/Cs and suggests the following: (1) the complex of ace-DB20C6 and Cs⁺ is formed with an ace-DB20C6/Cs molar ratio of 1/1 and (2) the two benzene rings of ace-DB20C6 fold around Cs⁺ above the center of the crown ether ring of ace-DB20C6.     

Quantitative Analysis of Cs Extraction by Some Dialkoxycalix[4]Arene-Crown-6 Extractants

Cesium extraction from acidic media by seven dialkoxy-calix[4]arene-crown-6 compounds in several diluents was studied. 2-Nonanone was found to be a suitable diluent for cesium extraction. Nitric acid concentration variation reveals a maximum distribution ratio, whose position depends on extractant and diluent. This maximum was explained quantitatively by a competitive extraction of H⁺. An analytical mass-action extraction model accounting for activity effects is proposed that fits correctly the different datasets. The analysis showed a nitrate hyper-stoichiometry in alkyl ketone diluents. This effect yields efficient back-extraction at low acidity. Benzo substitution on the crown ether lowers nitric acid extraction, improves sodium separation, but also degrades potassium and rubidium separation.     

Video-assisted thoracoscopic surgery of bullous and bleb disorders of the lung using endoscopic stapling device

The video-assisted thoracic surgical (VATS) approach appears to be a viable alternative to thoracotomy when surgical management of bullous and bleb disorders of the lung is required. Fifty patients with giant bullae (n = 6) and spontaneous pneumothoraces (n = 44) were recently treated by our group using the VATS approach and endoscopic stapling devices. Of the 50 patients, 47 were managed completely by the VATS approach, including six giant bullae that were asymptomatic in five and infectious in one and 41 pneumothoraces, of which 16 were first episode and 25 with recurrent pneumothorax. Median operating times for the bullous and bleb excisions were 147.8 and 45.9 min, respectively (p < 0.01), and median chest tube durations were 5.2 and 1.2 days, respectively (p < 0.05). There was no mortality, and significant morbidity was limited to prolonged air leak in more than 5 days in three patients and postoperative atelectasis in two patients. Median hospital stays of patients with bullous excision was 11.3 days compared with 4.7 days of those with bleb excision. We conclude that the VATS treatment is a safe, effective procedure in patients with bullous and bleb disorders of the lung even in asymptomatic giant bullae or spontaneous pneumothoraces with the first episode. The advantages of the VATS approach for these diseases are ease of operation, less pain, early mobility, and superior cosmetic results.