Gelling behavior of MgAl2O4 slurries with a common dispersant

MgAl₂O₄ transparent ceramics were shaped by a commonly used polyacrylic acid (PAA), which acted as both dispersant and gelling agent. The spinel slurries were prepared by ball-milling MgAl₂O₄ powder, PAA, and water in an attrition mill. The gelling of slurries happened at room temperature in air atmosphere without any other organic additive. The gelling mechanism was the formation of chelates between Mg²⁺ and carboxyl groups (-COO⁻) of PAA. The frequency-based testing method was applied to investigate the gelling process of the as-prepared slurry. In addition, a novel in situ characterization method based on a modified indentation testing was invented to better understand the strengthening of the wet green body with time and to guide when demolding could be carried out. After sintering, transparent MgAl₂O₄ ceramics with high in-line transmittance were resulted.     

Highly oriented α-Al2O3 transparent ceramics shaped by shear force

Alumina platelets were arranged horizontally in submicron alumina particles by shear force in the flow of slurries during casting. The obtained alumina green bodies with platelets were pressureless-sintered in vacuum, producing ceramics with thoroughly oriented grains and high transmittance. The effects of sintering parameters on the densification, microstructure evolution, and orientation degree of alumina ceramics were investigated and discussed. The results showed that the densification, grain size, orientation degree, and in-line transmittance were increased with increasing sintering temperature. The enhancement of orientation degree was mainly coherent with grain growth. The grain-oriented samples exhibited a much higher in-line transmittance (at 600 nm) of 61 % than that of the grain random sample (29 %). Moreover, the transmission remained a high level in the ultraviolet range (<300 nm).     

Investigation report of geotechnical disaster on river area due to typhoon landfall three times on Okhotsk region,Hokkaido, Japan

For one week from August 17 to 23, 2016, three consecutive typhoons made landfall in Hokkaido for the first time on record. These typhoons and the front they stimulated brought record-breaking torrential rain over the eastern part of Hokkaido. To investigate the damage to grounds and rivers resulting from this rainfall, the Japan Society of Civil Engineers (JSCE) and the Japanese Geotechnical Society (JGS) formed a disaster research group to conduct an investigation. This report provides the results of the investigation into damage to the grounds of areas along the Tokoro River of the Okhotsk region, Hokkaido, that suffered from this tremendous and diverse disaster. Specifically, the report describes the situation of the levees which were broken and eroded by the overflowing water, the shape of the levee bodies, the levee body soil properties examined by observation of the sections, as well as the occurrence of sand boiling and air blows. The washout of road embankments as well as damage to road bridge mounting fills and abutment backfills were also investigated. The investigation has demonstrated the need to clarify the resistance of the abutment backfills and levee bodies to flowing water as well as the geotechnical predominant factors in order to clarify the mechanisms behind erosion and washout, the need to review new measures that allow for the scale of sand boiling and resultant changes in levee body stability, and the fact that the existing embankments were able to temporarily suppress the flooding water which had spilled over from the river. Furthermore, although it has been identified that the findings of a study on an embankment washout associated with a tsunami can be applied to measures taken against the overflowing water, it has also been found necessary to clarify the predominant geotechnical factors using model tests and to use a more sophisticated analytical approach to establish a geotechnical stability review as soon as possible in order to prevent the levees and embankments from being eroded and washed out due to overflowing water.     

Smoking and small, dense low-density lipoprotein particles: cross-sectional study

All forms of tobacco cause cardiovascular disease, and tobacco-related disease is a leading cause of death worldwide. Smoking oxidizes low-density lipoprotein (LDL) particles, and oxidized LDL particles are thought to play an early and critical role in atherosclerogenesis. Hyper-low-density lipoproteinemia is one of the risk factors for cardiovascular disease, but small, dense LDL particles have been associated with an increased risk for cardiovascular disease. Small, dense LDL correlates with some cardiovascular risk factors such as diabetes mellitus, hypertriglyceridemia, hypo-high-density lipoproteinemia, and hypertension. Although smoking is also a major risk factor for cardiovascular disease, the relationship between smoking and small, dense LDL particles has not been described previously. Our cross-sectional study examined this relationship in a population of 18 healthy young adult men (9 smokers and 9 never-smokers, aged 21-24 years) from the same college. Concentrations of blood lipids and the LDL migration index (LDL-MI) were examined. Although concentrations of blood lipids did not differ between smokers and never-smokers, the LDL-MI had a strong tendency to be lower in smokers. The LDL-MI is larger in the presence of a greater proportion of small, dense LDL particles. These results indicate that tobacco smoking is associated with a decrease in the proportion of small, dense LDL particles. Regardless of these surprising results, we do not recommend smoking, given that it is a major cause of cardiovascular disease.     

Statistical optimization of a DC-RF hybrid plasma flow system for in-flight particle treatment

There are many input parameters to control a DC-RF hybrid plasma flow system, such as total gas flow rate, central gas flow rate, swirl gas ratio, RF power and DC power. Furthermore, the interactive effects among these parameters should be considered. In the present study, statistical analysis using simple linear model is conducted to clarify the effects of the input parameters and their interactions on the outputs such as particle residence time and average temperature in a DC-RF hybrid plasma flow system. The thermofluid characteristics of a DC-RF hybrid plasma flow are compared with those of an RF plasma flow. It is shown that the plasma characteristics are changed drastically by adding even small DC power. Furthermore, controllability is also improved by optimizing the operating conditions of a DC-RF hybrid plasma flow system.     

Effects of Coarse Particles on the Gelcasting of Ceramic Foams

In order to study the effects of coarse particles on the gelcasting of ceramic foams, a coarse powder with a similar sintering ability as that of fine powder was designed. It was prepared by grinding the presintered foams manufactured using fine powder and by sieving with 200-mesh sieves. The resultant coarse powder was mixed with the fine powder to manufacture ceramic foams by direct foaming and the gelcasting method. The viscosities of suspensions with different fractions of coarse powder were close to each other at high shear rates. The flexural strength of the foams obtained by the mixed powders was about 10 MPa, which was about 25% lower than that obtained by the fine powder, while the permeability of the foams by mixed powders was about 30% higher than that without coarse powder. On the other hand, both the flexural strength and the permeability of the foams by the mixed powders had no clear relation with the fraction of coarse powder when it varied in the range of 5%–40%.     

Gelcasting and Pressureless Sintering of Translucent Alumina Ceramics

Gelcasting is a very useful technique for producing ceramic parts with complex shapes. In this work, gelcasting in air and pressureless sintering in hydrogen were applied to manufacture translucent alumina ceramics. A stable suspension with 75 wt% solids was prepared by ball milling. Trapped bubbles were removed completely before casting to obtain homogeneous green bodies. Final sintering was carried out in a hydrogen furnace at 1850°C for 3 h. Homogeneous microstructures of both calcined and sintered bodies were obtained. The in-line transmission of the sample with a thickness of 0.5 mm increased gently from 9% to 10% in the wavelength range of 190–1100 nm.     

Uncertainty quantification via bayesian inference using sequential monte carlo methods for CO2 adsorption process

This work presents the uncertainty quantification, which includes parametric inference along with uncertainty propagation, for CO₂ adsorption in a hollow fiber sorbent, a complex dynamic chemical process. Parametric inference via Bayesian approach is performed using Sequential Monte Carlo, a completely parallel algorithm, and the predictions are obtained by propagating the posterior distribution through the model. The presence of residual variability in the observed data and model inadequacy often present a significant challenge in performing the parametric inference. In this work, residual variability in the observed data is handled by three different approaches: (a) by performing inference with isolated data sets, (b) by increasing the uncertainty in model parameters, and finally, (c) by using a model discrepancy term to account for the uncertainty. The pros and cons of each of the three approaches are illustrated along with the predicted distributions of CO₂ breakthrough capacity for a scaled‐up process. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3352–3368, 2016     

Primary structure of microbial transglutaminase from Streptoverticillium sp. strain s-8112

The complete amino acid sequence of transglutaminase (EC 2.3.2.13) (TGase), which is produced by a microorganism, Streptoverticillium sp. strain s-8112, and catalyzes the acyl transfer reaction between gamma-carboxyamide groups of glutamine residues in proteins and various primary amines, has been established by a combination of fast atom bombardment mass spectrometry and standard Edman degradation of peptide fragments produced by treatment of the TGase with various proteolytic enzymes and purified by a reversed-phase high performance liquid chromatography. The TGase consists of 331 amino acid residues with a chemical molecular weight of 37,863, in agreement with the observed molecular weight (37,869.2 +/- 8.8) determined from its electrospray ionization mass spectrum. The sequence of the enzyme is very different from those of mammalian TGases represented by guinea pig liver enzyme. The enzyme contains a sole Cys residue, which is essential for its catalytic activity. Hydropathy analysis indicated that the secondary structure of the region around the active site Cys residue is similar to those of mammalian TGases. These results suggest that this microbial protein evolved by a different pathway from that of mammalian TGases and acquired acyl transfer activity during the evolutional process.     

Differential diagnosis of pulmonary tuberculosis

Differential diagnosis of pulmonary tuberculosis is discussed. Chest X-ray findings of pulmonary tuberculosis may be greatly varied, because tuberculosis may cause three different lesions: an exudative lesion, a proliferative lesion, and a fibrotic lesion, and because it may invade all the structure. Thus, the differential diagnosis of pulmonary tuberculosis includes very many diseases. The most important differential diagnosis of nodule is tuberculoma and lung cancer. The clue of the diagnosis is the feature of the nodule and surrounding structure, such as pleural indentation, or knotching. There is, however, the limitation of the diagnosis by imaging: some tuberculoma may show the identical feature with the pulmonary adenocarcinoma. It is important to gather the pathological or bacteriological evidences by means of suitable procedures.