Detection of Multiple Blockages in Parallelized Microreactors

In a plant consisting of parallelized microreactors (MRs), the product quality is lowered because of a lack of flow uniformity among them when blockage occurs. It is not practical to install sensors in every MR from the viewpoint of cost when detecting the blocked MRs. In the previous study, the multiple blockage detection (MBD) method using a small number of sensors was proposed, but its performance became low when the number of sensors decreased. Here, the conventional algorithm for MBD is improved by considering the process behavior on blockage occurrence, and the effectiveness of the improved algorithm is demonstrated through a numerical case study. The effects of flow distributor types and sensor types on the MBD performance are numerically investigated.     

Phase fluctuations of cross-polarized signals at 4 GHz in fine weather on earth-space paths

On an earthspace propagation path with the low elevation angle of 10 deg, the phase between co- and crosspolar signals occasionally showed rapid and irregular fluctuations during fine weather. These fluctuations were generally significant during the daytime, and were strongly in phase with the occurrence of the copolar amplitude scintillations. This could be attributed to the combined effects of the crosspolar phase pattern of the receiving antenna and small fluctuations of the angle of arrival of the radiowaves.     

Formation and Characterization of Ce3ZrO8 Prepared by the Hydrazine Method

A compound denoted as (Ce_0.75Zr_0.25)O₂ (Ce, ZrO₈) is formed near room temperature from cerium and zirconium nitrates using hydrazine monohydrate. It has a cubic unit cell with a = 0.5342 nm. Characterization of powders heated to various temperatures at 10°C/min demonstrates that the specific surface area does not decrease below 20 mVg until >1000°C.     

Extensions of polyacrylic acid ammonium salts in the adsorption layer to fluidize alumina slurries

An average shell volume occupied in the adsorption layer on alumina by a polyacrylic acid ammonium salts molecule (PAA) defined as the average area occupied by an adsorbed PAA on alumina multiplied by the average thickness of the water layer at the limit of thickening, has been calculated from the adsorbed amount of PAA and from the flow points of alumina in the presence of PAA of different molecular weights. A steric effect of the PAA dispersant on the dispersion of alumina resulted in a flow with no yield stress. This was due to the change of the extension of PAA in the adsorption shell from a sphere to an ellipsoid with a long axis which exceeded the effective distance that the van der Waals attraction force reaches at a molecular weight for the PAA of between 10 000–20 000.     

Effect of Forming Pressure on the Internal Structure of Alumina Green Bodies Examined with Immersion Liquid Technique

Green bodies prepared by compaction of alumina granules were made transparent by an immersion liquid technique, and the internal structure was characterized with an optical microscope to study the effect of forming pressure on the internal structure. Clear images obtained by the technique provide more detailed information than other existing methods for structures ranging from one to tens of micrometers. Intergranular pores were present between unfractured granules. Their sizes and concentration tended to decrease with increasing forming pressure. However, pores were clearly present even in the green body prepared at 600 MPa. A rod- and needlelike feature was also found and was concluded to correspond to a high-density region. The significance of large pores and high-density regions on processing as well as the details of the technique is discussed.     

Hydroliquefaction of low-sulfur coals using iron carbonyl complexes—Sulfur as catalysts

Hydroliquefaction of low-sulfur Australian coals (Wandoan and Yallourn) was studied using iron carbonyl complexes as catalyst. The addition of Fe(CO)₅ (2.8 wt% Fe of coal) increased coal conversion from 48.6 to 85.2% for Wandoan coal, and from 36.7 to 69.7% for Yallourn coal in 1-methylnaphthalene at 425°C under an initial hydrogen pressure of 50 kg cm^?2. When molecular sulfur was added to iron carbonyls (Fe(CO)₅, Fe₂(CO)₉ and Fe₃(CO)₁₂), higher coal converions ( > 92%) and higher oil yields (>46%) were obtained, along with an increase in the amount of hydrogen transferred to coal from the gas phase (0.2 to 2.8%, d.a.f. coal basis). In the liquefaction studies using a hydrogen donor solvent, tetralin, Fe(CO)₅S catalyst increased the amount of hydrogen absorbed from the gaseous phase and decreased the amount of naphthalene dehydrogenated from tetralin. The direct hydrogen transfer reaction from molecular hydrogen to coal fragment radicals seems to be a major reaction pathway. Organic sulfur compounds, dimethyldisulfide and benzothiophene, and inorganic FeS₂ and NiS were found to be good sulfur sources to Fe(CO)₅. From X-ray diffraction analyses of liquefaction residues, it is concluded that Fe(CO)₅ was converted into pyrrhotite (Fe_1?xS) when sulfur was present, but into Fe₃O₄ in the absence of sulfur.     

GABA and glutamate levels in the substantia nigra reticulata following repetitive cerebral ischemia in gerbils

Repetitive cerebral ischemia produces more severe damage than a similar single duration insult. We have previously shown that, in gerbils, damage in the substantia nigra reticulata (SNr) is seen with repetitive insults rather than a single insult. We have also shown that there is a progressive decrease in the extracellular GABA in the striatum in the days preceding such damage, speculating that a loss of GABA may be in part responsible for this damage. This study evaluates the GABA levels in the SNr in animals exposed to repetitive ischemic insults. Each animal received a total of three ischemic insults of 3-min duration at hourly intervals. In vivo microdialysis was carried out to analyze the GABA and glutamate dialysate levels on Days 1, 3, 5, 7, and 14 following the ischemic insult. In the control and treated (ischemic) animals, there was a significant increase in the GABA levels with the introduction of nipecotic acid on Days 1, 3, 5, and 14. However, on Day 7 there was a significant attenuation in the GABA response to nipecotic acid in the treated animals in comparison to the controls. The glutamate levels in the treated animals were similar to the control animals on Days 1, 3, 5, and 7. However, on Day 14 the glutamate levels were significantly lower than on previous days. Our experiments for the first time measure extracellular glutamate and GABA responses in the SNr in animals exposed to repetitive ischemic insults. Our experiments show that there is a significant decrease in the GABA concentrations at a time when ischemic damage is developing in this region. This confirms our hypothesis that a decrease in GABA may be one factor contributing to neuronal damage during the period following repetitive ischemic insults. Further, the rebound increase in GABA levels on Day 14 with a concomitant fall in glutamate levels would indicate that reparative processes are still active in the 2 weeks following the insult.     

Dependence of thin film transistor characteristics on thedeposition conditions of silicon nitride and amorphous silicon

The systematic relation between thin film transistors' (TFT's) characteristics and the deposition conditions of amorphous silicon nitride (a-SiN) films and hydrogenated amorphous silicon (a-Si:H) films is investigated. It is observed that field effect mobility μ_FE and threshold voltage V_th of the TFT's strongly depend on the deposition conditions of these films. The maximum μ_FE of 0.88 cm²/V·s is obtained for the TFT of which a-SiN film is deposited at a pressure of 85 Pa. This phenomenon is due to the variation of the interface states density between a-Si:H film and a-SiN film     

Effects of partial recrystallization on high-cycle fatigue deformation and crack generation of a nitrogen-strengthened 32Mn-7Cr austenitic steel at liquid-nitrogen temperature

To achieve higher fatigue resistance against subsurface crack generation, both the refinement of grain structure and the introduction of mobile dislocations on various slip systems have been shown to be effective in the 32Mn-7Cr austenitic steel. A novel treatment which consisted of cold grooved rolling and partial recrystallization was introduced to modify the microstructure. High-cycle fatigue properties and fatigue-crack generation were investigated for both the solution-treated (ST) and the partially recrystallized (PR) materials at 77 K. The PR material displayed higher fatigue strength than the ST material, especially in the high-cycle regime. No subsurface crack generation was detected for the PR material; however, it appeared in the lower peak stress and/or in the longer-life range for the ST material. Intergranular facets formed a subsurface crack initiation site in the ST material. Since the dislocation structure that developed in the fatigued PR material assisted homogeneous and multidirectional plastic deformation, the localized deformation and/or the stress concentration at the grain boundaries by coplanar arrays were believed to be relieved. Therefore, intergranular cracking due to incompatibility at a grain boundary may disappear.