Influence of high-temperature creep stress on growth of thermally grown oxide in thermal barrier coatings

Recently, a large local stress has been found, caused by the change of both the diffusion rate of oxygen through an existing oxide and the rate of chemical reaction at the oxide/oxidized material interface. Since high thermal stress occurs in the thermal barrier coating (TBC) system, the volume expansion of the newly grown oxide, and centrifugal force, the growth rate of the thermally grown oxide (TGO) may change depending on the temperature, the exposure time, and the stress. The aim of this study is to make clear the influence of stress on the growth rate of the TGO thickness under static oxidation. The results show that TGO thickening was affected by the increase of not only the exposure temperature but also the applied stress. The tensile stress in a longitudinal direction in a TBC system due to the applied load makes the oxidant transport and oxide flow more easy, i.e., the tensile stress promotes a volume expansion of newly formed oxide. The increase rate of the TGO thickness was approximately 34% when the applied stress increased from 0 to 205 MPa at 900 °C for 325 h, and approximately 25% when the stress increased from 0 to 150 MPa at 950 °C for 125 h.     

Development of novel clutch utilizing self-locking mechanisms of belt

A novel clutch was developed by using the self-locking property of belt friction. The frictional force is generated automatically by the torque applied. The belt starts to coil around the cylinder by the frictional force of the trigger pin at the end of the belt. Once the belt comes in contact with the cylinder, the belt coils automatically around the cylinder by the frictional force. Then the belt is locked firmly around the cylinder by the self-locking property of belt friction as long as driving torque is applying. The clutch is able to transmit rotational torque even in an off-centered condition.     

Model system of bulking and flocculation in mixed culture of Sphaerotilus sp. and Pseudomonas sp. for dissolved oxygen deficiency and high loading

A mixed continuous culture system was made up as a model for bulking and flocculation phenomena of the activated sludge to study the effect of dissolved oxygen (DO) deficiency and the effect of high organic loading. The system consisted of a floc forming bacterium and a filamentous bacterium which were isolated from the activated sludge and were identified as Pseudomonas sp. and Sphaerotilus sp., respectively. Sphaerotilus sp. had potential to cause a filamentous bulking phenomenon on the activated sludge. It was observed that the filamentous microorganism showed three kinds of growth form, filamentous form, pellet form and dispersed form, and that the floc former showed two kinds of growth form, good floc form and dispersed form. In the model system, these changes of growth form of two microorganisms, which could be thought as the cause of settling characteristics changes, depended on the DO level and the dilution rate (as a substitution for organic loading). The DO level also influence the aggregative ability of each microorganism and the maximum oxygen uptake rate, Q_O2max, of filamentous microorganism. The proportions of both microorganisms in model system were inverted reversibly by the DO level or the dilution rate changes.     

Effective Utilization of Concrete Sludge as Soil Improvement Materials

The amount of muddy soil generated from various kinds of construction sites is always problematic. It is very difficult to treat muddy soil because of its low strength and high water content. But, the reuse of muddy soil is necessary to reduce the total amount of industrial wastes. Surplus concrete is also in a similar situation. Coarse and fine aggregates are removed from surplus concrete as an intermediate treatment, however, concrete sludge still remains. The authors propose a reuse method that involves the muddy soil being mixed with concrete sludge as an improvement material. The possibility of the utilization of concrete sludge was investigated through laboratory experiments. As a result, it was found that the unconfined compressive strength of the improved soil mixed with concrete sludge increased as the curing proceeded.     

Burning behavior of sedan passenger cars

Four full-scale fire experiments using 4-door sedan passenger cars were carried out. The cars were ignited either at the splashguard of the right rear wheel or at the left front seat in the passenger compartment with a gasoline spill. The temperature inside the burning car and the mass loss rate were measured. The burning of the 4-door sedan was composed of three compartmental fires: the engine compartment, the passenger compartment, and the rear part inclusive of the fuel. In the experiments where ignition was initiated at the splashguard, the flame spread in the following order: to the rear part of the car, to the passenger compartment, and to the engine compartment. Breakage of the window glass markedly affected the spread of fire into the passenger compartment. The quantity of gasoline in the fuel tank also affected the speed of spread of the fire, because the gasoline ignited at an early stage of the fire. In the experiment where ignition was initiated in the passenger compartment, the fire gained force after the windshield was broken entirely. The flame spread in the following order: to the passenger compartment, to the engine compartment, and to the rear part of the car. The temperature within the passenger compartment peaked at 1000 °C. The heat release rate (HRR) curves showed several peaks depending on the burning of the three compartments. The HRR increased markedly when the fire spread to several different parts of the car at the same time. The HHR peaked at 3 MW when the passenger compartment and fuel (gasoline) burned simultaneously. The measured HRR curves were characterized by superposition of a Boltzmann curve and a Gaussian curve in order to obtain a model, which allowed us to make a more precise prediction of the fire spread probability from a burning car to nearby structures. The HRRs of burning cars were described by the sum of HRR from each compartment.     

Open-loop control of a stepping motor using oscillation-suppressiveexciting sequence tuned by genetic algorithm

A new method for suppression of rotor oscillation in open-loop drive of a stepping motor is proposed. In this method, the torque equilibrium position of the motor is manipulated so as to guarantee insensitiveness to the variation of rotor inertia; the motion of the equilibrium position is made to be nonoscillatory, and the frequency of the motion is bound within the region limited by the maximum frequency determined by considering the performance on the condition with the largest inertial load. The exciting sequence used for a single-step drive is tuned by using the technique of genetic algorithm. It is shown by the experimental results that rotor oscillation can be well suppressed on the load conditions with different inertial loads     

Toughening of aromatic diamine-cured epoxy resins by poly(butylene phthalate)s and the related copolyesters

Aromatic polyesters, prepared by the reaction of aromatic dicarboxylic acids and 1,4-butanediol, were used to improve the toughness of bisphenol-A diglycidyl ether epoxy resin cured with p,p′-diaminodiphenyl sulfone. These polyesters contained poly(butylene phthalate)s (PBP), poly(butylene phthalate-co-butylene isophthalate)s, poly(butylene phthalate-co-butylene terephthalate)s, and poly(butylene phthalate-co-butylene 2,6-naphthalene dicarboxylate)s. All aromatic polyesters used in this study were soluble in the epoxy resin without solvents and were found to be effective as modifiers for toughening the cured epoxy resin. For example, the inclusion of 20 wt % PBP (MW 16,300) led to a 120% increase in the fracture toughness (K_IC) of the cured resin with no loss of mechanical and thermal properties. The toughening mechanism was discussed in terms of the morphological and dynamic viscoelastic behaviors of the modified epoxy resin system. © 1996 John Wiley & Sons, Inc.     

Efficient Suppression of Abdominal Aortic Aneurysm Expansion in Rats through Systemic Administration of Statin-Loaded Nanomedicine

Abdominal aortic aneurysm (AAA) is a life-threatening disease. However, no systemically injectable drug has been approved for AAA treatment due to low bioavailability. Polymeric micelles are nanomedicines that have the potential to improve therapeutic efficacy by selectively delivering drugs into disease sites, and research has mainly focused on cancer treatments. Here, we developed a statin-loaded polymeric micelle to treat AAAs in rat models. The micelle showed medicinal efficacy by preventing aortic aneurysm expansion in a dose-dependent manner. Furthermore, the micelle-injected group showed decreased macrophage infiltration and decreased matrix metalloproteinase-9 activity in cases of AAA.     

Functional Characterization of Tomato Phytochrome A and B1B2 Mutants in Response to Heat Stress

Heat stress (HS) is a prevalent negative factor affecting plant growth and development, as it is predominant worldwide and threatens agriculture on a large scale. PHYTOCHROMES (PHYs) are photoreceptors that control plant growth and development, and the stress signaling response partially interferes with their activity. PHYA, B1, and B2 are the most well-known PHY types in tomatoes. Our study aimed to identify the role of tomato ‘Money Maker’ phyA and phyB1B2 mutants in stable and fluctuating high temperatures at different growth stages. In the seed germination and vegetative growth stages, the phy mutants were HS tolerant, while during the flowering stage the phy mutants revealed two opposing roles depending on the HS exposure period. The response of the phy mutants to HS during the fruiting stage showed similarity to WT. The most obvious stage that demonstrated phy mutants’ tolerance was the vegetative growth stage, in which a high degree of membrane stability and enhanced water preservation were achieved by the regulation of stomatal closure. In addition, both mutants upregulated the expression of heat-responsive genes related to heat tolerance. In addition to lower malondialdehyde accumulation, the phyA mutant enhanced proline levels. These results clarified the response of tomato phyA and phyB1B2 mutants to HS.     

Substitutional reaction in Si–O network of molecular dynamics-modeled liquid Na2SiO3: Microscopic and statistical study

The study of the bond breaking and formation processes, that is, the chemical reaction, in the Si–O network structure in liquid alkali silicates at temperatures around or higher than the glass-transition temperature is important for understanding kinetic processes such as the structural relaxation of the network, viscous flow, and diffusion of the network former ions. Herein, novel methods for analyzing the reactions in a molecular-dynamics-modeled liquid Na₂SiO₃ were used to confirm the following results: (a) the substitutional reactions (in which a nonbridging O ion of a Si–O chain or a SiO₄ tetrahedron attacks the Si ion of another chain from backside of a bridging O ion, which acts as the leaving group, and the bridging O leaves the Si ion) primarily occur in the Si–O network of liquid Na₂SiO₃; and (b) The abundance ratio of Q_n species can be quantitatively reproduced by the reaction rate.