A microscopic study of dropwise condensationUne etude microscopique de la condensation en gouttesMikroskopische untersuchung der tropfenkondensationMикpocкoпиччcкoч иccлчдoвчнич кчпчльнoй кoндчнcчции

In dropwise condensation most of the heat is transferred by the active droplets whose sizes are below a certain characteristic value so that the thermal conduction resistance inside them may become negligible. In this paper the local heat transfer coefficient is determined experimentally at the very part of the condenser surface which is covered solely by the active droplets. The rate of increase in the condensate volume in a domain newly exposed by coalescence between droplets was analyzed from a high-speed high-magnification cine film record of the condenser surface. By assuming the complete coverage of the surface by droplets, the local heat transfer coefficient obtained in this way was equated to the interfacial heat transfer coefficient. As a result, the condensation coefficient of water was estimated at around 0.5.     

Formation of uranium mononitride by the reaction of uranium dioxide with carbon in ammonia and a mixture of hydrogen and nitrogen— I synthesis of high purity UN

Formation of uranium mononitride by the reaction between UO₂ and C in an ammonia stream, a mixed 75%H₂-25%N₂ stream and a mixed 8%H₂-92%N₂ stream has been studied at 1400–1600°C. For the formation of high purity UN, there exists a minimum mixing ratio ($\text{C}\text{UO}{}_2$). It largely depends on the reaction atmosphere and temperature. The mixing ratio in the three atmospheres decreases in the following order: ammonia >75%H₂ + 25%N₂ > 8%H₂ + 92%N₂, and it decreases with increasing temperature. The total amount of impurities (carbon + oxygen) in the UN obtained is in the range of 500–1000 ppm. The time necessary for completion of the reaction in ammonia is shorter than in a mixed hydrogennitrogen.     

Increase in the resistance of stenotic coronary segment by intravenous infusion of isoproterenol

Curantil intracarotid injection resulted in brain blood supply and in brain oxygen consumption increase as well as in redox processes normalization in 75 cats with main brain arteries occlusion and heart insufficiency induced by chemical necrosis of the myocardium. A single intravenous injection of a higher curantil dose resulted in a significantly less effect. Long-term (3-72 hours) curantil infusion led to the improvement of the functions disturbed (limb movements, speech, vision) in 32 of 42 patients with brain ischemic insult. The greatest therapeutic efficacy was observed in patients with nonobturated brain infarction induced by brain vascular spasm or cardiocerebral vascular insufficiency.     

Functional analysis of mammalian genes using amphibian embryonic cells

We describe a method that contributes to the analysis of the functions of mammalian genes by the use of amphibian embryos and electron microscopy. Following forced expression of specific mammalian genes in amphibian embryos, we attempted to deduce the function of each gene from the ultrastructural changes in cell organelles caused by its overexpression. This method has been applied to the analysis of the functions of genes isolated from mammalian skeletal muscle and the results have shown it to be an effective technique for such studies. We present the results of our experimental studies using this method and discuss its usefulness in analyzing mammalians genes.     

Single-molecule imaging of the dynamic interactions between macromolecules

In recent years, the development of single-molecule detection techniques has allowed the dynamic properties of biomolecules, which are normally obscured in conventional ensemble measurements, to be measured. One of these single-molecule detection techniques allows the measurement of dissociation and association events of individual molecules to be measured. This technique is based on the unique premise that the mobility between molecules that are bound and the mobility between those that are free in solution are different. The binding of ATP at the beginning and its dissociation at the end of the hydrolysis reaction were detected at the single-molecule level in real time. In this study, we extended this technique to image the dynamic interactions between large biomolecules (protein/protein and protein/polysaccharide). The binding and dissociation of fluorescently labeled macromolecules to partner molecules fixed on a glass surface were visualized by total internal reflection fluorescence microscopy. The dynamic interactions between the proteins in two energy conversion systems, that is, signaling proteins and enzyme molecules moving on dextran, have been measured. In these systems, the dynamic interactions were sensitive to the factors determining the chemical reactions. Thus, the dynamic interactions monitored in the single-molecule measurements provided useful information to further the understanding of the underlying mechanisms of energy conversion systems.     

High-throughput construction method for expression vector of peptides for NMR study suited for isotopic labeling

Fusion protein constructs for labeled peptides were generated with the 114 amino acid thioredoxin (TRX), coupled with the incorporation of a histidine tag for affinity purification. Two tandem AhdI sites were designed in the multiple cloning site of the fusion vector according to our novel unidirectional TA cloning methodology named PRESAT-vector, allowing one-step background-free cloning of DNA fragments. Constructs were designed to incorporate the four residue sequence Ile-Asp-Gly-Arg to generate pure peptides following Factor Xa cleavage of the fusion protein. The system is efficient and cost-effective for isotopic labeling of peptides for heteronuclear NMR studies. Seven peptides of varying length, including pituitary adenylate cyclase activating polypeptide (PACAP), vasoactive intestinal peptide (VIP) and ubiquitin interacting motif (UIM), were expressed using this TRX fusion system to give soluble fusion protein constructs in all cases. Three alternative methods for the preparation of DNA fragments were applied depending on the length of the peptides, such as polymerase chain reaction, chemical synthesis or a 'semi-synthetic method', which is a combination of chemical synthesis and enzymatic extension. The ability easily to construct, express and purify recombinant peptides in a high-throughput manner will be of enormous benefit in areas of biomedical research and drug discovery.     

Cognitive map formation through sequence encoding by theta phase precession

The rodent hippocampus has been thought to represent the spatial environment as a cognitive map. The associative connections in the hippocampus imply that a neural entity represents the map as a geometrical network of hippocampal cells in terms of a chart. According to recent experimental observations, the cells fire successively relative to the theta oscillation of the local field potential, called theta phase precession, when the animal is running. This observation suggests the learning of temporal sequences with asymmetric connections in the hippocampus, but it also gives rather inconsistent implications on the formation of the chart that should consist of symmetric connections for space coding. In this study, we hypothesize that the chart is generated with theta phase coding through the integration of asymmetric connections. Our computer experiments use a hippocampal network model to demonstrate that a geometrical network is formed through running experiences in a few minutes. Asymmetric connections are found to remain and distribute heterogeneously in the network. The obtained network exhibits the spatial localization of activities at each instance as the chart does and their propagation that represents behavioral motions with multidirectional properties. We conclude that theta phase precession and the Hebbian rule with a time delay can provide the neural principles for learning the cognitive map.     

Analysis on split failure of cladding of high burnup BWR rods in reactivity-initiated accident conditions by RANNS code

A computer code RANNS was developed to analyze fuel rod behaviors in the reactivity-initiated accident (RIA) conditions. RANNS performs thermal and finite-element mechanical calculation for a single rod in axis-symmetric geometry, where fuel pellet consists of 36 equal-volume ring elements and cladding metallic wall consists of eight equal-thickness ring elements and one outer oxide element. The code can calculate temperature profile inside the rod, contact pressure generated by pellet–clad mechanical interaction (PCMI), stress–strain distribution and their interactions elaborately. An experimental analysis by RANNS begins with pre-test conditions of irradiated rod which are given by the fuel performance code FEMAXI-6.In the present study, analysis was performed on the simulated RIA experiments in the “nuclear safety research reactor” (NSRR), FK-10 and FK-12, with high burnup BWR rods in a cold-start up condition, and stress–strain evolution in the PCMI process was calculated extensively. In the analysis, the pellet–clad bonding was assumed both in the heat conduction and in mechanical restraint. The calculated hoop strain increase was compared with the measured strain gauge data, and satisfactory agreement was obtained. Simulation calculations with broader power pulses anticipated in RIA of commercial BWR were carried out and the resulted cladding hoop stress was compared with the failure stress estimated by comparison of analysis with experimental data.     

High quality gate insulator film formation on SiC using by microwave-excited high-density plasma

High quality gate insulator film formation on 4H-SiC substrate is demonstrated. The insulator films were formed by the PECVD and radical oxynitridation using microwave-excited high-density plasma with NO gas at low temperature. The oxide fixed charge and the interface trap density can be dramatically reduced by NO gas radical oxynitridation after the oxide film formed by the PECVD compared with by direct oxynitridation on 4H-SiC. SIMS profiles show carbon profile in these fabricated gate insulator films. It is confirmed that the electrical property is improved as the amount of remaining carbon in the insulator film decreases.