Influence of Slurry Flocculation on the Character and Compaction of Spray-Dried Silicon Nitride Granules

The effect of slurry flocculation on the characteristics of silicon nitride granules prepared by the spray drying process is investigated. The flocculation state of an aqueous silicon nitride slurry is controlled by adding nitric acid and evaluated as a function of pH. Dense and hard silicon nitride granules result from a well-dispersed slurry having a high pH (e.g., 10.8). These hard granules retain their shape in green compacts and form detrimental defects. Lowering the pH of the slurry to a certain value (e.g., pH 7.9) results in slurry flocculation. Granules prepared from this flocculated slurry have low density and low diametral compression strength and contribute to the elimination of large pores in green compacts.     

Novel design procedure of broad-band multilayer antireflectioncoatings for optical and optoelectronic devices

A novel design procedure of broad-band multilayer antireflection (AR) coatings for optical and optoelectronic devices is proposed. The design algorithm is based on the optical admittance detuning, with the bandwidth of finite reflectivity as a new merit function. Coating structures consist of only two materials with nonquarter-wave thicknesses. Numerical mappings on the four-layer structure showed four optimizing regions where an optimized four-layer AR coating on 1.55 μm GaInAs-AlGaInAs MQW semiconductor laser facet was predicted to have a broad bandwidth of 106 mm for a reflectivity of less than 10^-5. TiO₂ and SiO₂ were electron-beam (EB) evaporated to form the four-layer AR coating on glass and InP substrates with an ion-beam assist and a real time in situ optical thickness monitor and experimentally verify its broad-band performance     

Regurgitation through the morphologically pulmonary valve after additional aortopulmonary anastomosis

OBJECTIVE: Oesophagectomies have a high morbidity rate, mainly related to pulmonary complications. The aim of this work was to assess whether the thoracoscopic approach could reduce this morbidity. PATIENTS AND METHODS: We conducted a prospective study of the results of 26 attempts of esophagectomy using a right thoracoscopic approach. There were 17 males and 9 females having an average age of 47. The indication was a squamous cell carcinoma in 19 patients, an adenocarcinoma in 1 patient, a melanoma in 1 patient and a caustic stenosis in 5. The whole oesophagus was mobilized thoracoscopically, and the eosophagectomy was completed through the abdomen. The reconstruction was achieved using a gastric pull-through and a cervical anastomosis. RESULTS: There were 5 failures for the following reasons: unresectable carcinoma (1 case), large tumour making a thoracoscopic dissection unsafe (1 case) and incomplete lung collapse making the exposure of the posterior mediastinum difficult (2 cases). The average time of the thoracoscopic procedure was 135 min. The post-operative course was uneventful in all but 5 patients who had a pulmonary complication: atelectasis (3 cases), right purulent pleural effusion (1 case), acute respiratory distress syndrome (1 case). The latter complication was lethal. Four out of 5 respiratory complications occurred in patients for whom the dissection was considered as difficult. Among the other complications, there were 5 anastomotic leakages and 3 laryngeal nerve palsy. The mortality rate was 3.8%. CONCLUSION: These initial results do not show a real benefit of the thoracoscopic approach for eosophageal dissection, especially for difficult oesophagectomies. Further evaluation of the technique is needed.     

Nucleotide excision repair proteins may be involved in the fixation of glyoxal-induced mutagenesis in Escherichia coli

Earlier studies in our laboratories demonstrated that particles of a number of snack foods that are retained on the dentition accumulate fermentable sugars and short-chain carboxylic acids (SCCA; acetic, formic, lactic, and propionic) to different degrees. The present study was undertaken to test the hypothesis that the accumulated SCCA can induce a gingival inflammatory response. Five periodontally and medically healthy subjects were given portions of plain doughnuts (high SCCA levels) or oatmeal cookie (low SCCA), or had the SCCA applied directly to the gingival margins of designated teeth. Subjects were given wax to chew, or nothing, as controls. Inflammation was assessed by measurements of subgingival temperature, flow rates of gingival crevicular fluid (GCF), and neutrophil emigration into GCF. Subgingival temperatures of the maxillary gingiva rose by 1.32 +/- 0.30 degrees C (mean +/- SE) 5 min after the subjects consumed the doughnuts and remained elevated for at least 1 hr. These values were significantly higher than those obtained from subjects after ingestion of oatmeal cookies (0.63 +/- 0.17 degree C; p < 0.01), consistent with the low levels of SCCA in the retained cookie particles. Wax chewing elicited a similar response, indicating a masticatory effect on the gingiva. Gingival temperatures in the unchallenged controls remained unchanged. Neutrophil emigration into the GCF was significantly elevated in subjects after doughnut consumption. Rinses with a solution of SCCA, or application of the SCCA to the gingiva, also brought about significant elevations in subgingival temperature and neutrophil emigration. The findings describe the inflammatory effects of food ingestion on the gingiva of healthy human subjects, and support the hypothesis that SCCA in the particles of retained food are at least partly responsible for the observed responses.     

Changes in volatile flavour components of soybeans during roasting

Volatile concentrates were prepared from whole soybeans, roasted at 200°C for 10, 20 and 30 min, by steam distillation under reduced pressure followed by ether extraction, and analysed by gas chromatography and gas chromatography-mass spectrometry, in comparison with the volatile concentrate from raw soybean flour.Major flavour components of raw soybean, such as n-hexanol, 1-octen-3-ol and n-hexanal, decreased during the course of roasting, but the rate of this decrease was not rapid, especially between 10 and 20 minutes' roasting. During the roasting period, alkylated pyrazines, oxygenated furans, oxygenated pyrroles and phenols were formed or increased markedly. On the other hand, sensory evaluation showed that a flavour change to ‘desirable’ from ‘beany’ or ‘objectionable’ occurred between 10 and 20 minutes' roasting. These results suggest that roast flavour masks the ‘beany’ flavour in soybean.     

Structure dependent axial mode stability in GaAlAs/GaAs injection lasers

The influence of structure on the saturation behaviour of mode gain and the axial mode stability is investigated for different types of AlGaAs injection lasers. Both experimental and theoretical results confirm that carrier confinement along the lateral direction is effective for axial mode stabilisation.     

Toyota electronic modulated air suspension system for the 1986Soarer

An electronically controlled air-suspension system is described that uses sensors to detect vehicle speed, throttle position, steering angle, height, and other factors related to vehicle attitude. Its electronic control unit (ECU) drives the actuators to control spring rate, damping force, and height. As a result, the system reduces changes in vehicle attitude such as rolls, dives, squats, etc., and also provides stable maneuverability in high-speed cruising and improved drive characteristics on rough roads. A newly developed single-chip microcomputer is used in the ECU. The actuators for the sporting rate and damping force use DC motors. The system also allows drivers to select preferred suspension characteristics from four modes, and displays on a CRT the suspension status     

Differences in strategies for carcinoma of the pancreas between Japan and western countries

This study defines normative flow velocity (FV) ranges for the common carotid (CCA), internal carotid (ICA) and middle cerebral arteries (MCA), compares them to subjects with nonfocal vascular disease (mild to moderate hypertension, diabetes, hyperlipidemia or coronary artery disease), and clarifies the association between carotid and MCA FVs. FVs were measured by carotid and transcranial Doppler ultrasonography in 278 healthy and 190 vascular-disease subjects. Normative FV ranges for CCA, ICA and MCA were large in healthy subjects, with modest gender and age differences. Vascular-disease subjects had similar FVs to healthy controls. MCA FVs were significantly correlated with carotid FVs (r ranged 0.26-0.50), but were only weakly or not significantly associated with them (beta ranged 0.08-0.18) when controlling for age and gender. These findings suggest that normative FVs are not affected by the presence of nonfocal vascular disease, but carotid FVs do not aid in assessing MCA FVs.