APPLICATION OF THE ENERGY DISSIPATION RATE CONCEPT TO NATURAL CONVECTION HEAT TRANSFER

A new model for turbulent natural convection heat transfer from an isothermal vertical plate is developed. It is based on a unified energy dissipation rate concept originally proposed by Calderbank and Moo-Young (Chem. Eng. Sci., 16, 39-54 (1961)). The proposed model is developed to include non-Newtonian flow behaviors. The predictions of the model are compared with published experimental and theoretical results. Satisfactory agreement is found and therefore the applicability of the energy dissipation rate concept to natural convection is confirmed.     

LIQUID-PHASE MASS TRANSFER COEFFICIENT IN SLURRY BUBBLE COLUMN REACTORS: THEORY AND EXPERIMENTAL DATA IN SIMULATED FERMENTATION MEDIA

Mass transfer in a slurry bubble column reactor was examined. A theoretical correlation for liquid-phase mass transfer coefficient was developed using a combination of Higbie's penetration theory and the Einstein-Li periodic viscous sublayer model. The proposed correlation predicts that the liquid-phase mass transfer coefficient decreases with an increase of the yield stress of slurries. The measurement of mass transfer rates was conducted in a 40-L bubble column reactor. The slurries containing low-density particles were simulated by aqueous carboxypolmethylene solutions. Satisfactory agreement was found between the proposed correlation and the experimental data.     

Combined surgery for coronary artery disease and thoracic aortic disease

Combined surgery in 6 cases who had coronary artery disease and thoracic aortic disease simultaneously was analyzed. Case # 1 had ascending aortic replacement under deep hypothermic circulatory arrest because of iatrogenic aortic dissection caused by aortic clamp during the routine coronary artery bypass grafting (CABG). Case # 2 had DeBakey type II chronic dissection. Case # 3 had type I aortic dissection 4 years after the initial CABG. Both case # 2 and # 3 had ascending aortic replacement under retrograde cerebral perfusion along with CABG. Transverse aortic replacement was performed in case # 4, # 5 and # 6 under selective cerebral perfusion along with CABG. Case # 4 was associated with ascending-transverse aortic aneurysm. Case # 5 had aortitis syndrome complicated with severe coronary ostial stenosis and cervical branch stenosis. Case # 6 also had aortitis syndrome, severe coronary ostial stenosis, heavily calcified ascending-transverse aorta, and mitral and aortic regurgitation. This case had mitral and aortic valve replacement additionally. Case # 2 died of low cardiac output syndrome and multi-organ failure postoperatively. Case # 4 did not recover from profound shock that followed the preoperative acute myocardial infarction. The problems of low cardiac output syndrome caused by long interval of ischemic cardiac arrest, and also the problems of proximal anastomotic site of saphenous vein grafts were discussed.     

Deep-submicrometer BiCMOS circuit technology for sub-10-ns ECL 4-MbDRAM's

A 0.3-μm sub-10-ns ECL 4-Mb BiCMOS DRAM design is described. The results obtained are: (1) a V_cc connection limiter with a BiCMOS output circuit is chosen due to ease of design, excellent device reliability and layout area; (2) a mostly CMOS periphery with a specific bipolar use provides better performances at high speed and low power; (3) the direct sensing scheme of a single-stage MOS preamplifier combined with a bipolar main amplifier offers high speed; and (4) the strict control of MOS transistor parameters has been proven to be more important in obtaining high speed DRAMs, based on the 4-Mb design     

Finite element analysis of magnetic circuits composed of axisymmetric and rectangular regions

A new approximate method is developed for calculating three-dimensional magnetic fields in magnetic circuits composed of connected axisymmetric and rectangular regions. Using this new method, fairly accurate solutions can be obtained when the leakage flux from the magnetic circuit is small. In this paper, the new method is explained and then the usefulness of the technique is clarified by comparing calculated and measured flux densities.     

A case of ventricular septal perforation treated surgically with an infarction exclusion technique

We report an 85-year-old woman with postinfarction interventricular septal perforation. She underwent successful emergent surgical treatment by a slightly modified method based on David-Komeda's procedure. Perforation in this case occurred four days after acute myocardial infarction. Preoperative Qp/Qs was 2.58, and pulmonary artery pressure was 34/25 mmHg. The area of infarction was large, and the perforation was the linear type 2.5 cm long near the apex. A probe was not able to pass through the perforation due to its complicated configuration. A double Xenomedica patch was sutured on the left side of the interventricular septum without excising the infarcted area. The suture line was placed on healthy myocardium apart from the infarcted area. The Xenomedica patch was sandwiched between the closure line of the ventriculotomy. Four days after surgery, residual shunt was observed by echocardiogram, but this subsequently disappeared on the 17th postoperative day. The patient was discharged from our hospital on the 57th postoperative day, and is now doing quite well.     

Uniform culture in solid-state fermentation with fungi and its efficient enzyme production

Solid-state fermentation (SSF) has attracted a lot of interest for carrying out high-level protein production in filamentous fungi. However, it has problems such as the fermentation heat generated during the culture in addition to the reduced mobility of substances. These conditions lead to a nonuniform state in the culture substrate and result in low reproducibility. We constructed a non-airflow box (NAB) with a moisture permeable fluoropolymer membrane, thereby making it possible to control and maintain uniform and optimal conditions in the substrate. For the NAB culture in Aspergillus oryzae, temperature and water content on/in the whole substrate were more consistent than for a traditional tray box (TB) culture. Total weight after the culture remained constant and dry conditions could be achieved during the culture. These data demonstrate the possibility of growing a uniform culture of the whole substrate for SSF. The NAB is advantageous because it allows for the control of exact temperature and water content in the substrate during the culture by allowing vapor with latent heat to dissipate out of the box. In addition, several enzymes in the NAB culture exhibited higher production levels than in the TB culture. We believe that culturing in the constructed NAB could become a standard technique for commercial SSF.     

FLAIR images of mild head trauma with transient amnesia

A newly advanced MRI pulse sequence, the FLAIR (fluid-attenuated inversion recovery) imaging, in which a long TE spin echo sequence is used with suppression of the CSF with an inversion pulse, displays the CSF space as a no signal intensity area. We examined 45 cases of mild head trauma with posttraumatic amnesia by FLAIR images and could detect some findings which could not be detected by CT scan and conventional MR images. These findings could be detected in many patients with long post-traumatic amnesia (over 2 hours), but they could not be detected in patients with short posttraumatic amnesia (within 30 mins). These findings existed surrounding lateral ventricles and we classified them into 3 types: type 1 is anterior horn of lateral ventricle, type 2 is the base of frontal lobe, type 3 is cerebral deep white matter. Some of them were examined again by FLAIR images a month later, and these findings had disappeared. We suspect that these lesions were brain edema or mild contusion without hemorrhage.