A particle‐in‐cell solution to the silo discharging problem

The problem of flow of a granular material during the process of discharging a silo is considered in the present paper. The mechanical behaviour of the material is described by the use of the model of the elastic–plastic solid with the Drucker–Prager yield condition and the non‐associative flow rule. The phenomenon of friction between the stored material and the silo walls is taken into account—the Coulomb model of friction is used in the analysis. The problem is analysed by means of the particle‐in‐cell method—a variant of the finite element method which enables to solve the pertinent equations of motion on an arbitrary computational mesh and trace state variables at points of the body chosen independently of the mesh. The method can be regarded as an arbitrary Lagrangian–Eulerian formulation of the finite element method, and overcomes the main drawback of the updated Lagrangian formulation of FEM related to mesh distortion. The entire process of discharging a silo can be analysed by this approach. The dynamic problem is solved by the use of the explicit time‐integration scheme. Several numerical examples are included. The plane strain and axisymmetric problems are solved for silos with flat bottoms and conical hoppers. Some results are compared with experimental ones. Copyright © 1999 John Wiley & Sons, Ltd.     

Rapid Production and Genetic Stability of Human Mesenchymal Progenitor Cells Derived from Human Somatic Cell Nuclear Transfer-Derived Pluripotent Stem Cells

Pluripotent stem cell-derived mesenchymal progenitor cells (PSC-MPCs) are primarily derived through two main methods: three-dimensional (3D) embryoid body-platform (EB formation) and the 2D direct differentiation method. We recently established somatic cell nuclear transfer (SCNT)-PSC lines and showed their stemness. In the present study, we produced SCNT-PSC-MPCs using a novel direct differentiation method, and the characteristics, gene expression, and genetic stability of these MPCs were compared with those derived through EB formation. The recovery and purification of SCNT-PSC-Direct-MPCs were significantly accelerated compared to those of the SCNT-PSC-EB-MPCs, but both types of MPCs expressed typical surface markers and exhibited similar proliferation and differentiation potentials. Additionally, the analysis of gene expression patterns using microarrays showed very similar patterns. Moreover, array CGH analysis showed that both SCNT-PSC-Direct-MPCs and SCNT-PSC-EB-MPCs exhibited no significant differences in copy number variation (CNV) or single-nucleotide polymorphism (SNP) frequency. These results indicate that SCNT-PSC-Direct-MPCs exhibited high genetic stability even after rapid differentiation into MPCs, and the rate at which directly derived MPCs reached a sufficient number was higher than that of MPCs derived through the EB method. Therefore, we suggest that the direct method of differentiating MPCs from SCNT-PSCs can improve the efficacy of SCNT-PSCs applied to allogeneic transplantation.     

The impacts of SILC and hot carrier induced drain leakage current on the refresh time in DRAM

This paper reports the temperature dependence of SILC and hot carrier induced drain leakage current, and their impact on the refresh time in Giga-bit level DRAM with practical considerations. SILC has been found to increase as the monitoring and stress temperature increases. Due to the generation of interface states, hot carrier induced pn junction leakage current and band-to-band tunneling current have been found to increase as the monitoring temperature increases.From the simulation results of a refresh circuit for Giga-bit level DRAM, it has been found that the increase of SILC with stress time is a dominant factor in refresh failure below 373K, and the pn junction leakage current will be a dominant factor at the high elevated temperature. It has been also observed that the increase of hot carrier induced drain leakage current can be a cause for the refresh failure.     

Effect of Oxidation State of Iron on Phase Separation in Sodium Silicate Glasses

The effect of the oxidation state of iron on the phase separation of x Na₂O·(100 – x )SiO₂ glasses, x = 18.56 and 13, containing 0.5 mol% Fe₂O₃ was studied. The oxidation state of iron in the glasses was varied by changing the melting conditions, such as melting temperature and melting atmosphere. The oxidation states of the iron ion were determined using colorimetric and UV–VIS–NIR spectrophotometric methods, and a comparison was made between the results obtained using these two methods. Immiscibility temperatures of the glasses were determined using opalescence and clearing methods. The immiscibility temperature of the sodium silicate binary glasses decreased ∼25°C with the addition of 0.5 mol% Fe₂O₃. The immiscibility temperature of the doped glasses increased slightly with increased concentration of Fe²⁺ ion in the glass. The prediction of immiscibility tendency on the addition of a minor amount of third component was made using models proposed by Tomozawa and Obara and Nakagawa and Izumitani. The Tomozawa and Obara model showed good agreement with measured immiscibility values.     

Study on functional microcapsules containing catalysts for controlling the curing time and temperature of epoxy resin

In this study, functional microcapsules (FMs) were designed for controlling the curing time and temperature of epoxy through modifications to thermally expandable microcapsules. The FMs were prepared with a mixture of liquid hydrocarbons and N,N-dimethylbenzylamine in the core, and acrylonitrile (AN)—methyl methacrylate copolymer or AN–methacrylate copolymer were used for the shell. Since the FMs were intentionally designed to have thermally vulnerable polymeric shells, the catalyst in the core could be released at the designated temperature. Therefore, FMs do not activate in epoxy at room temperature; rather, the FMs only become functional when the epoxy is cured under a heated atmosphere. Released catalyst at the higher temperature was confirmed by pyrolysis gas chromatography–mass spectrometry and optical microscopy. This study shows that the results will depend on the different compositions of liquid hydrocarbons and catalyst. Particle size of the capsules was changed with different ratio of catalyst and liquid hydrocarbon at the core and type of polymeric shell. Differential scanning calorimetry and rheometer results showed that higher catalyst loading resulted lower in crystalline and shear thickening temperature, respectively. Adhesion strength of epoxy containing FMs was analyzed by lap shear strength in order to detect the void effect due to released gas from the FM. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47499.     

A novel electrolytic process using a Cu cathode for the production of Mg metal from MgO

Journal of Applied Electrochemistry - An environmentally friendly and effective molten salt electrolysis process using a copper (Cu) cathode was developed for producing magnesium (Mg) metal from...     

Thermal expansion behavior of composites based on non-axisymmetric ellipsoidal particles

A new model for calculating the coefficients of thermal expansion, CTE, in all three coordinate directions is developed for composites containing non-axisymmetric, ellipsoidal particles, i.e., three-dimensional ellipsoids (a₁ ≠ a₂ ≠ a₃) characterized by two aspect ratios, ρα=a₁/a₃ and ρβ=a₁/a₂. The model makes use of Eshelby's equivalent tensor for the particles and utilizes the methodology from recent papers by Lee et al. The effects of the primary, ρ_α, and secondary, ρ_β, aspect ratios and filler volume fraction (0-6%) on the various CTE for nanocomposites containing aligned inclusions are demonstrated by calculations for a matrix of nylon 6 and a filler of montmorillonite single platelets. The CTE in the longitudinal direction, α11, decreases, as both aspect ratios increase. The CTE in the transverse direction, α22, decreases as ρα increases but increases as ρβ increases. The CTE in the normal direction, α33, is greater than that of the matrix and increases as ρα increases but decreases as ρβ increases.     

Effect of silymarin on gluconeogenesis and lactate production in exercising rats

In this study, we investigated the effects of silymarin (SM) on gluconeogenesis during exercise in rats. After 4 weeks of exercise, blood samples, liver, and skeletal muscle tissues were collected, and the levels of triglycerides (TG), lactate, peroxisome proliferator activated receptor gamma (PPARγ), phosphoenol pyruvate carboxykinase (PEPCK), pyruvate dehydrogenase kinase 4 (PDK4), and phosphorylated 5-AMP activated protein kinase (AMPK) were measured. The TG and lactate level of the serum were reduced. In addition, the expression of Akt, PEPCK, and PPARγ in liver was decreased as well as the expression of AMPK in muscle. On the contrary, the level of PDK4 in muscle was increased. These results showed that that administration of SM ameliorated exerciseinduced gluconeogenesis and β-oxidation through the regulation of PPARγ, PEPCK, and PDK4. Thus, intake of SM during exercise may improve endurance by modulating of the metabolism of glucose, lipids, and lactate.     

The Interplay of Mahalanobis Distance and Firm Capabilities on MNC Subsidiary Exits from Host Countries

We examine how the cross-national Mahalanobis distance between home and host countries may affect a multinational corporation subsidiary’s exit from its host country by applying a longitudinal Cox proportional hazard model analysis using data from Korean MNCs between 1990 and 2012. Our findings show that increasing cross-national distance is positively related to the likelihood of a subsidiary’s exit from the host country for most cross-national distance dimensions, while increasing cross-national distance is negatively related to the likelihood of a subsidiary’s exit from the host country for knowledge and global connectedness dimensions. However, the positive relationship between the seven dimensions of cross-national distance and subsidiary exit becomes weaker when the MNC has strong technological and experiential capabilities, while the negative relationship between two dimensions (i.e., knowledge and global connectedness) of cross-national distance and subsidiary exit becomes stronger. Our study contributes to the international business literature by examining the impact of diverse cross-national distance dimensions on subsidiary exit by showing the significance of firm capabilities in overcoming cross-national distance challenges, as well as by finding both a “problem-focused view” and “positive organizational perspective” in the results.     

Identification of a new analogue of sildenafil added illegally to a functional food marketed for penile erectile dysfunction

A new analogue of sildenafil was discovered to have been added illegally to a functional food marketed for penile erectile dysfunction. The structure of the analogue was established by various NMR spectroscopic techniques (including DEPT, COSY, TOCSY, HMQC, HMBC). Because of the addition of a methylene group to sildenafil, the main ingredient of Viagra®, it was given the name homosildenafil, and this has never been reported previously. An analytical method using HPLC was proposed. Homosildenafil was added as a new inspection item and other foods have since been discovered to contain it.