Lattice Boltzmann simulation of asymptotic longitudinal mass dispersion in reconstructed random porous media

To research macroscopic mass transport characteristics of porous media, a lattice Boltzmann method (LBM) approach was utilized to calculate asymptotic longitudinal mass dispersion. In this study, a D2Q9 model with multi‐relaxation‐time (MRT) collision operator, which is appropriate for incompressible flow with a high Péclet number without refining the lattice, was chosen. With respect to the microstructure of porous media, random placement (RP) method was applied to obtain randomly positioned particles. Based on the exhausted numerical results presented in the study, a new correlation of longitudinal mass dispersion was established. By comparing with available experimental data in the literature, reasonable agreements are observed in a wide porosity range from 0.3 to 0.7, indicating the validity of the proposed correlation. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2770–2780, 2018     

Power characteristics of unsteadily forward–reverse rotating impellers in an unbaffled aerated agitated vessel

Power characteristics of an unbaffled aerated agitated vessel with unsteadily forward‐reverse rotating impellers, ie a new type of gas–liquid agitator named ‘AJITER’, treating viscous Newtonian liquids were studied experimentally. Measurements were first made on the agitation torque, ie the torque on the drive shaft on which forward–reverse rotating impellers with four delta‐type blades were attached, and the data obtained were analyzed by fitting them to an equation consisting of two terms with respect to the resistance of the fluid, one due to viscous drag and the other due to added moment of inertia. The effects of operating conditions and physical properties of liquids on the drag and added moment of inertia coefficients were then evaluated, and empirical relationships which estimate values of these coefficients, useful to predict the unsteady behavior and magnitude of agitation torque, were presented. Furthermore, equations were developed for estimating the average and maximum power consumptions as a function of the drag and added moment of inertia coefficients. Prediction of respective power levels in AJITER by these equations was also discussed. © 2001 Society of Chemical Industry     

Structurally Diverse Polyamines: Solid‐Phase Synthesis and Interaction with DNA

A versatile solid‐phase approach based on peptide chemistry was used to construct four classes of structurally diverse polyamines with modified backbones: linear, partially constrained, branched, and cyclic. Their effects on DNA duplex stability and structure were examined. The polyamines showed distinct activities, thus highlighting the importance of polyamine backbone structure. Interestingly, the rank order of polyamine ability for DNA compaction was different to that for their effects on circular dichroism and melting temperature, thus indicating that these polyamines have distinct effects on secondary and higher‐order structures of DNA.     

Drying of Sewage Sludge During Composting in an Updraft Dryer with the Concept of Using Self-Energy Generated Within the System

An innovative technology for sewage treatment systems is proposed. A mixture of sewage sludge and char particle is subjected to drying in the progress of composting in an updraft column. Exothermic heat generated during composting is utilized for energy of sludge drying. The char particle in the mixture contributes to enhancement of composting and drying rate. This study presents drying and composting behaviors of sludge to examine the effect of char addition. A fundamental drying experiment was carried out by hot-air heating of the sample in a small vessel. The drying characteristic curve for a mixture of sludge and char was greater than the sample of only sludge over a whole period if the drying rates were compared with the same moisture content. The drying behavior could be analyzed with a reasonable agreement by the water front receding model. The enhancement effect of drying and composting of sludge by char addition was confirmed by examination using a pilot scale of the updraft column whose volume was 50 m³. Sludge with 400% dry base (80% wet base) in moisture content could be dried successfully to lower moisture content than 67% dry base (40% wet base) only by exothermic heat during composting without supplying any auxiliary energy from the outside, and the treatment time was reduced by mixing char in sludge. The behavior was analyzed with a satisfactory agreement by a theoretical model employing moisture diffusion parameters determined from the drying characteristic curve.     

Oxidation Protection of MgO–C Refractories by Means of Al8B4C7

The effect of Al₈B₄C₇ used as an antioxidant in MgO–C refractories and the behavior of Al₈B₄C₇ in CO gas were investigated in the present study. Al₈B₄C₇ was found to react with CO gas, to form Al₂O₃( s ), B₂O₃( l ), and C( s ), at temperatures >1100°C. The Al₂O₃ reacts with MgO to form MgAl₂O₄ near the surface of the material. At the same time, B₂O₃( l ) evaporates and reacts with MgO, to form a liquid phase, at >1333°C, the eutectic point between 3MgO·B₂O₃ and MgO. The coexistence of the liquid and MgAl₂O₄ makes the protective layer more dense, thus inhibiting oxidation of the refractory. At >1333°C, the process apparently is controlled by oxygen diffusion, whereas it is controlled by chemical reaction when the temperature is <1333°C.     

Enantio-differentiating hydrogenation of prochiral ketones over modified nickel

This article reviews the enantio-differentiating hydrogenation of prochiral ketones over a asymmetrically modified catalyst, focusing on the hydrogenation of simple prochiral alkanones. The parameters affecting catalytic activity and enantiodifferentiating ability are considerable in number, and each parameter should be optimized in order to attain a highperformance enantio-differentiating catalyst. Optimization of the parameters and the mode of enantio-differentiation are discussed and compared with the enantio-differentiating hydrogenation of β-ketoesters.     

Sillimanite‐mullite transformation observed in synchrotron X‐ray diffraction experiments

High‐resolution synchrotron powder X‐ray diffraction (XRD) experiments were conducted to clarify the transformation of sillimanite to mullite (mullitization) and determine the mullitization temperature (T_c). We were able to distinguish sillimanite and mullite in the XRD patterns, despite their very similar crystallographic parameters, and to detect the appearance of small mullite peaks among sillimanite peaks. Analysis of the Johnson‐Mehl‐Avrami (JMA) equation for mullitization ratio (ζ) revealed that at temperatures T≥1240°C the mullitization had the same kinetics. The activation energy E at T≥1240°C obtained from the Arrhenius plot was 679.8 kJ mol^?1. In analysis using a time‐temperature‐transformation diagram for mullitization, a mullitization curve of ζ=1% can be described as where t is time, n is a reaction‐mechanism‐dependent parameter determined as 0.324 by JMA‐analysis, k₀ is the frequency factor, E_A is the activation energy for atomic diffusion, and represents the activation energy for nucleation. The results of fitting the data to this equation were T_c=1199°C, A=3.9×10⁶ kJ mol^?1 K^?2, E_A=605 kJ mol^?1, and k₀=3.65×10¹⁵. We conclude that the boundary between sillimanite and mullite+SiO₂ in the phase diagram is ~1200°C.     

URINARY 2-HYDROXYFLUORENE AND 1-HYDROXYPYRENE LEVELS IN SMOKERS AND NONSMOKERS IN JAPAN AND THAILAND

2-Hydroxyfluorene (2-OHF) and 1-hydroxypyrene (1-OHP) in urine samples of smokers and nonsmokers were determined separately by using two high-performance liquid chromatography (HPLC) systems with fluorescence detection. Urine samples were collected from the subjects who lived in Japan and Thailand, and were not occupationally exposed to polycyclic aromatic hydrocarbons (PAHs). The mean concentrations of 2-OHF and 1-OHP of Thai smokers (0.75 and 3.03 μmol/mol creatinine) and nonsmokers (0.22 and 0.91 μmol/mol creatinine) were both higher than those of Japanese smokers (0.26 and 0.12 μmol/mol creatinine) and nonsmokers (0.04 and 0.06 μmol/mol creatinine), respectively. The difference between smokers and nonsmokers was more significant for 2-OHF than for 1-OHP, reflecting the higher intake of fluorene in the vapor phase by the smoking. Moreover, the higher urinary levels of both 2-OHF and 1-OHP were observed in Thai nonsmokers than those in Japanese nonsmokers, suggesting the higher background exposure to PAHs of Thai subjects.     

Peel Test Using Nonstationary Peel Method

The cohesive peel spectra of pressure-sensitive adhesive (PSA) tapes have been measured using a non-stationary peel tester. The experimental evidence and a viscoelastic analysis based on a peel model indicate that there are no significant effects of acceleration in the normal rate region. The nonstationary peel tester can be regarded as a useful tool for testing and evaluating PSA tapes.     

Drilling of Multi-Layer Printed-Circuit Boards

With the recent improvement in the performance and miniaturization of computers, communication equipment, and various other pieces of electronic apparatus, multi-layer printed-circuit boards have attained wide usage. The need for drilling such boards has been increasing. A multi-layer printed-circuit board used in the computer is usually provided with 2,000 to 3,000 holes 0.5-0.9 mm in diameter, each made by a NC high-speed automatic drilling machine. It is estimated that the number of holes made for the drilling of printed-circuit boards might well have reached 200 billion in 1971. Drilling printed-circuit boards is accomplished by using a drill, a punch, a laser beam, an electron beam and liquid jet, or by other methods. It is considered that the use of a drill is most suitable from the point of view of surface quality of drilled holes, reliability of their plating through holes, workability, and so forth.