SEDIMENTATION OF PARTICLES IN NON-NEWTONIAN FLUIDS

The influence of non-Newtonian flow behavior on sedimentation velocity of particles is investigated using an approximate solution for the motion of an assemblage of solid spheres presented previously by the authors. It is theoretically predicted that the pseudoplaslicity decreases the sedimentation velocity and its reduction is pronounced at large voidage. The present theory is discussed using the available empirical correlations.     

Drag and mass transfer in non-newtonian flows through multi-particle systems at low reynolds numbers

An approximate solution for the motion of an assemblage of solid spheres moving through a power-law fluid at low Reynolds numbers is obtained using HapThe theoretical predictions based on Kuwabara's zero-vorticity cell model are very similar to those based on Happel's model. An approximation technique     

Reaction kinetics of sodium bisulfite and dissolved oxygen in seawater and their applications to seawater reverse osmosis

Recently, single-stage seawater reverse osmosis (SWRO) in the Middle East has been developed. In this process, removing dissolved oxygen (DO) from the feed seawater is very important for membrane life. The reaction rate of sodium bisulfite (SBS) and DO in seawater was investigated to apply DO removal system to the SWRO. The reaction in seawater was very fast because the salinity had a positive catalytic effect and the bicarbonate ion kept the pH suitable for the reaction. By applying these results, Toray's PEC-1000 membrane modules have shown excellent performance and long durability.     

Numerical analysis on abnormal thyristor forward voltage increase due to heavy doping in gated p-base layer

An abnormal forward voltage increase was observed for a p-base gated double diffused n⁺pn^?p⁺ high power thyristor with high impurity concentration at the n⁺-p emitter-base junction. Accurate numerical analysis shows that heavy doping effects are the most responsible mechanism for the abnormality and that depletion layer formation at the center junction accompanies it.It will be shown that appropriate control of the impurity concentration at the emitter-base junction is necessary to avoid this abnormality by realizing the common base transistor current gain of greater than 0.73 for n⁺n^?-portion.     

Discussion of ``Optimization by Integer Programming of Constrained Reliability Problems with Several Modes of Failure'

Tillman's 1969 treatment for components with several modes of failure and series (or parallel) redundancy using the components is discussed. This note claims that his treatment is wrong. Author replies and further discussion are provided.     

Transport of fixed gases in radiation-stabilized poly(vinyl chloride)

Poly(vinyl chloride) was reacted with sodium N-methyl dithiocarbamate to produce a modified PVC containing N-methyl dithiocarbamate of varying degrees of substitution. The resulting adducts were markedly more stable when subjected to γ-radiation than the unmodified PVC. The transport parameters (permeability, solubility, and diffusivity) of fixed gases were determined in modified and unmodified films. Although the radiation stability was dramatically improved by this novel substitution, the barrier properties of the PVC were only slightly changed by the controlled substitution of N-methyl dithiocarbamate.     

Visualization of PVDF nanofibers coated on filter paper using fluorescein silica nanoparticles

Fluorescein silica nanoparticles (NPs) were prepared using a silane compound bound between fluorescein‐N‐hydroxysuccinimide (NHS‐Fluorescein) and 3‐aminopropylorthosilicate by a sol–gel method. The fluorescein‐silica NPs were mixed with a poly(vinylidene fluoride) (PVDF) solution, and the solution loaded with the NPs was electrospun on a filter paper. Scanning electron microscopy and transmission electron microscopy images confirmed the encapsulation of the fluorescein silica NPs in the PVDF nanofibers. Laser scanning confocal microscopy (LSCM) images showed fluorescein silica NPs as dots, and photoluminescence (PL) images obtained using a fluoroanalyzer indicated the emission of uniform PL from filter papers coated with fluorescein‐silica‐NP‐encapsulated PVDF nanofibers. It was demonstrated that the fluorescein silica NPs enabled PVDF nanofibers coated on a filter paper to be easily visualized. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45125.     

Study on capacity fade factors of lithium secondary batteries using LiNi0.7Co0.3O2 and graphite-coke hybrid carbon

In our previous work, 10 Wh-class (30650 type) lithium secondary batteries, which were fabricated with LiNi_0.7Co_0.3O₂ positive electrodes and graphite-coke hybrid carbon negative electrodes, showed an excellent cycle performance of 2350 cycles at a 70% state of charge charge-discharge cycle test. However, this cycle performance is insufficient for dispersed energy storage systems, such as home use load leveling systems. In order to clarify the capacity fade factors of the cell, we focused our investigation on the ability discharge capacity of the positive and negative electrodes after 2350 cycles. Although the cell capacity deteriorated to 70% of its initial capacity after 2350 cycles, it was confirmed that the LiNi_0.7Co_0.3O₂ positive electrode and graphite-coke hybrid negative electrode after 2350 cycles still have sufficient ability discharge capacity of 86 and 92% of their initial capacity, respectively. Accompanied by the result for a composition analysis of the positive electrode material by inductively coupled plasma (ICP) spectroscopy and atomic absorption spectrometry (AAS), electrochemical active lithium decreased and the Li_xNi_0.7Co_0.3O₂ positive electrode could be charged-discharged in a narrow range of between x=0.41 and 0.66 in the battery, although it had enough ability discharge capacity that can use between x=0.36 and 0.87. It is predicted that solid electrolyte interface formation by electrolyte decomposition on the carbon negative electrode during the charge-discharge cycle test is a main factor of the decrease of electrochemical active lithium.     

Synthesis of pentavalent imidovanadium complexes and their catalyses for the polymerization of ethylene and propylene

Imidovanadium complexes with cyclopentadienyl (Cp) ligands—(Cp)V(?NC₆H₄Me‐4)Cl₂ (1), (Cp)V(?N^tBu)Cl₂ (2), and (^tBuCp)V(?N^tBu)Cl₂ (3; ^tBuCp = tert‐butylcyclopentadienyl)—were synthesized through the reaction of imidovanadium trichloride with (trimethylsilyl)cyclopentadiene derivatives. The molecular structure of 3 was determined by X‐ray crystallography. The monocyclopentadienyl complex 1 exhibited moderate activity in combination with methylaluminoxane [MAO; 10.3 kg of polyethylene (mol of V)^?1 h^?1 atm^?1], whereas similar complexes with bulky ^tBu groups, 2 and 3, were less active. (2‐Methyl‐8‐quinolinolato)imidovanadium complexes, V(?NR)(O ?N)Cl₂ (R = C₆H₃ⁱPr₂‐2,6 (4) or n‐hexyl (5), O ?N = 2‐methyl‐8‐quinolinolato), were obtained from the reaction of imidovanadium trichloride with 2‐methyl‐8‐quinolinol. Upon activation with modified MAO, complex 4 showed moderate activities for the polymerization of ethylene at room temperature. The complex 5/MAO system also exhibited moderate activity at 0°C. The polyethylenes obtained by these complexes had considerably high melting points, which indicated the formation of linear polyethylene. Moreover, the 5/dried MAO system showed propylene polymerization activities and produced polymers with considerably high molecular weights and narrow molecular weight distributions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1008–1015, 2005     

GAS-LIQUID MASS TRANSFER CHARACTERISTICS OF LARGE-SCALE IMPELLERS: EMPIRICAL CORRELATIONS OF GAS HOLDUPS AND VOLUMETRIC MASS TRANSFER COEFFICIENTS IN STIRRED TANKS

Gas dispersion with large-scale impellers consisting of modified large paddle impellers in stirred tanks, with rather large ratios of both impeller diameter and impeller height to tank diameter, was experimentally examined in transition and turbulent mixing ranges. Gas holdups and volumetric gas-liquid mass transfer coefficients with large-scale impellers, i.e., Maxblend and Fullzone impellers, were measured in 0.31 and 0.6 m I.D. stirred tanks, and the gas dispersion performance of large-scale impellers was compared with that of double conventional small-scale high-speed impeller systems, i.e., double four-flat blade disk turbine impellers and double four-flat paddle impellers.

The gas holdups of the large-scale impellers were comparable with those of the small-scale impeller systems at a given rotational speed. The volumetric gas-liquid mass transfer coefficients for large-scale impellers were also similar to those of the small-scale impeller systems. It was found that the large-scale impellers are not more energy efficient than the small-scale impellers in obtaining good gas dispersion.

Empirical correlations for gas holdups and volumetric gas-liquid mass transfer coefficients were developed. They fit the experimental data in transition and turbulent mixing ranges reasonably well, with correlation factors greater than 0.84.