In-Ho Jung

Critical thermodynamic evaluation and optimization of the MgO-Al2O3, CaO-MgO-Al2O3, and MgO-Al2O3-SiO2 Systems

A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties of all oxide phases in the MgO-Al2O3, CaO-MgO-Al2O3, and MgO-Al2O3-SiO2 systems at 1 bar total pressure are presented. Optimized model equations for the thermodynamic properties of all phases are obtained that reproduce all available thermodynamic and phase equilibrium data within experimental error limits from 25 °C to above the liquidus temperatures at all compositions. The database of the model parameters can be used along with software for Gibbs energy minimization to calculate all thermodynamic properties and any type of phase diagram section. The modified quasichemical model was used for the liquid slag phase and sublattice models, based upon the compound energy formalism, were used for the spinel, pyroxene, and monoxide solid solutions. The use of physically reasonable models means that the models can be used to predict thermodynamic properties and phase equilibria in composition and temperature regions where data are not available.

A model to calculate the viscosity of silicate melts

Abstract A model has been developed that links the viscosities of silicate melts to their thermodynamic properties. Over the past several years, through critical evaluation of all available thermodynamic and phase equilibrium data, we have developed a quantitative thermodynamic description of multicomponent silicate melts using the Modified Quasichemical Model for short-range ordering. The local structure of the liquid, in terms of the bridging behavior of oxygen, calculated using our thermodynamic model allows us to characterize the structure of the liquid semi-quantitatively using the concepts of Q-species and connectivity of Q-species. The viscosity is modeled by optimizing viscosity parameters that are related to the structure of the liquid. The viscosity of pure liquid silica is modeled using four model parameters and every other unary liquid is modeled using two. The viscosity of all binary liquids is reproduced within experimental accuracy by optimizing one or at most two binary viscosity parameters for each system. In the present article the equations for the viscosity model are derived and analyses for the experimentally well-established systems CaO – SiO2 MgO – SiO2, NaO0.5 – SiO2, KO0.5 – SiO2 and AlO1.5 – SiO2 are presented. This is the first step in the development of a predictive model for the viscosity of multicomponent silicate melts that will be presented in part II.

The analgesic and anti-inflammatory effect of WIN-34B, a new herbal formula for osteoarthritis composed of Lonicera japonica Thunb and Anemarrhena asphodeloides BUNGE in vivo

ETHNOPHARMACOLOGICAL RELEVANCE Lonicera japonica Thunb and Anemarrhena asphodeloides BUNGE have been used for the treatment of a variety of inflammatory diseases, cold and infective diseases in many countries, including Korea and China. AIM OF THE STUDY This study aimed to assess the anti-nociceptive and anti-inflammatory activities of n-butanol fraction (WIN-34B) prepared from dried flowers of Lonicera japonica and dried roots of Anemarrhena asphodeloides as potential novel treatment of osteoarthritis. MATERIALS AND METHODS Anti-nociceptive activities of WIN-34B (100, 200 and 400 mg/kg, p.o.) were measured using acetic acid-induced writhing response, formalin-induced paw licking, hot plate, radiant heat tail-flick, carrageenan-induced paw pressure, and Hargreaves tests, respectively. Anti-inflammatory activities of WIN-34B (100, 200 and 400 mg/kg, p.o.) were assessed using acetic acid-induced vascular permeability, carrageenan-induced paw edema, and croton oil-induced ear edema. Anti-osteoarthritis effect of WIN-34B was analyzed using monosodium iodoacetate (MIA)-induced osteoarthritis animal model. RESULTS WIN-34B exhibited better anti-inflammatory activity than that of celecoxib in carrageenan at the dose of 200 mg/kg and croton oil-induced paw edema and ear edema at the doses of 200 and 400 mg/kg. WIN-34B exhibited significant anti-inflammatory effects on vascular permeability. WIN-34B also exhibited significant anti-nociceptive activities in the late phase of formalin-induced paw licking and writhing response model in mice. In radiant heat tail-flick and carrageenan-induced paw pressure tests, WIN-34B at the dose of 400 mg/kg and at the doses of 200 and 400 mg/kg presented similar activities to indomethacin and celecoxib. Compared to indomethacin WIN-34B at 400mg/kg showed similar or better anti-nociceptive activities after 1 and 2h of theraphy in the hot plate test and better anti-nociceptive activity than that of celecoxib in Hargreves test. In the MIA-induced osteoarthritis animal models, WIN-34B at 400 mg/kg exhibited similar or better anti-nociceptive property than that of celecoxib throughout the pain measurement periods. CONCLUSION When compared to celecoxib, WIN-34B exhibited similar or better anti-nociceptive and anti-inflammatory activities in osteoarthritic animal models, which may become a potential novel treatment for osteoarthritis.

A model to calculate the viscosity of silicate melts Part II: The NaO0.5-MgO-CaO-AlO1.5-SiO2 system

Abstract Our recently developed model to describe the viscosity of binary silicate melts is extended to describe and predict the viscosities of multicomponent silicate melts. The viscosity of multicomponent melts containing no AlO1.5 is modeled to vary linearly as a function of the mole fractions of the basic oxides at constant SiO2 mole fraction. Systems containing AlO1.5 show a more or less pronounced viscosity maximum close to the charge compensating composition. This maximum is caused by some of the Al3+ taking on the same structural role as Si4+, thereby participating in the formation of the silica network. The network-forming Al3+ must remain associated with either one Na+, or two Al3+ ions must remain associated with one Mg2+ or Ca2+, in order to assure charge neutrality. To take this into account we introduce the associates NaAlO2, CaAl2O4 and MgAl2O4 that correspond to charge compensated network-forming Al3+. The Gibbs energy of formation of these associates determines the amount of Al3+ that takes on the network-forming role. We assume the effect on viscosity of network-forming Al3+ to be the same as Si4+ and optimize the Gibbs energies of the associates to reproduce the experimental viscosity data. Viscosities in ternary silicate systems without AlO1.5 are quantitatively predicted with no additional ternary model parameters. Ternary systems MeOx – SiO2 – AlO1.5 are modeled with only two temperature-independent ternary parameters per system. The model not only reproduces the magnitude of the observed viscosity maximum, but also its complex shape, asymmetry and temperature dependence.

Promotion of texture weakening in magnesium by alloying and thermomechanical processing: (I) alloying

The recrystallization and texture evolution of four Mg–Zn–Ce sheets with a warm-rolled microstructure obtained through two stages that can be characterised as rough rolling and finish rolling were investigated at different stages of post-rolling annealing. On annealing, the same regions of the microstructure, located by hardness indentations, were examined and tracked by electron backscatter diffraction (EBSD). Furthermore, intragranular misorientation axes (IGMA) analysis was used to investigate the associated deformation mechanisms in the as-deformed material. By combining these two methods, the development of the recrystallization microstructure was investigated and important aspects, such as preferential nucleation sites, correlation between activated deformation mechanism and initial orientation of the recrystallized grains, were studied. The results showed that the Mg–1Zn–1Ce alloy, which had the highest Ce/Zn ratio, showed the weakest as-rolled texture and the most homogenous distribution of shear banding/twinning. The IGMA analysis also showed that in Mg–1Zn–1Ce, other types of dislocations rather than basal 〈a〉 were activated; in particular, prismatic 〈a〉 type was activated during deformation. Therefore, the weakening of recrystallization texture during rolling resulting from the addition of RE elements was linked with a change in dynamic recrystallization (DRX) behaviour. Since the Mg–1Zn–1Ce alloy corresponds to the highest level of Ce in solid solution, the observed texture weakening was possibly due to decreasing grain boundary mobility as a result of solute partitioning of RE elements to dislocations and grain boundaries.

The memory ameliorating effects of INM-176, an ethanolic extract of Angelica gigas, against scopolamine- or Aβ1–42-induced cognitive dysfunction in mice

ETHNOPHARMACOLOGICAL RELEVANCE Alzheimers disease is a neurodegenerative disorder associated with cognitive impairment and cholinergic neuronal death. INM-176 is a standardized ethanolic extract of Angelica gigas Nakai that has been traditionally used in herbal medicine in China, Japan, and Korea to treat anemia or as a sedative. We investigated whether INM-176 exhibits anti-amnesic effects. MATERIALS AND METHODS Memory impairment was induced by scopolamine, a cholinergic muscarinic receptor antagonist, or amyloid β(1-42) (Aβ(1-42)) protein. Anti-amnesic effects of INM-176 were measured by the passive avoidance and the Morris water maze tasks in mice. We also examined the effect of INM-176 on the acetylcholinesterase activity, as well as Aβ(1-42) protein-induced astrogliosis or cholinergic neuronal loss in the brain. RESULTS Scopolamine-induced cognitive dysfunction was significantly attenuated by a single or sub-chronic administration of INM-176 in the passive avoidance and the Morris water maze tasks. A single or sub-chronic administration of INM-176 also ameliorated memory impairments induced by Aβ(1-42) protein. INM-176 inhibited acetylcholinesterase activity in the hippocampal tissue in vitro and ex vivo. In addition, INM-176 attenuated the Aβ(1-42) protein-induced astrocyte activation in the hippocampus as well as cholinergic neuronal damage in the CA3 region of the hippocampus and the nucleus basalis of Meynert. CONCLUSION These results suggest that the memory ameliorating effects of INM-176 on scopolamine- or Aβ(1-42) protein-induced memory impairment are mediated, in part, via acetylcholinesterase inhibition and neuroprotective activities.

Influence of strain rate on hot deformation behaviour and texture evolution of AZ31B

Abstract In the present work, the effects of strain rate on the flow behaviour and microstructure evolution of AZ31 Mg alloy were studied by compression testing over a wide range of strain rates (0·01–100 s−1) and temperatures (300–450°C). In addition, the influence of different strain rates on the dynamic recrystallisation (DRX) mechanisms and texture evolution was investigated. The results showed that with increasing strain rate, the twin induced DRX fraction increased at a constant temperature, and the contribution of continuous DRX decreased. On increasing the strain rate, the formation of twins and subsequent twin induced DRX intensified the basal texture in the deformed sample. In addition, the recrystallised volume fraction increased significantly with strain rate. The flow behaviour was fitted to two types of constitutive equations: power law and hyperbolic sine. Average activation energies of about 162 and 135 kJ mol−1 were obtained for the peak and steady state strain respectively.

Atomistic modeling of pure Li and Mg–Li system

Interatomic potentials for pure Li and the Mg–Li binary system have been developed based on the second nearest-neighbor modified embedded-atom method formalism. The potentials can describe various fundamental physical properties of pure Li (bulk, point defect, planar defect and thermal properties) and alloy behaviors (thermodynamic, structural and elastic properties) in reasonable agreement with experimental data or higher-level calculations. The applicability of the potential to atomistic investigations on the deformation behavior of Mg alloys and the effect of Li is demonstrated.

Thermodynamic modeling of the B2O3–SiO2 and B2O3–Al2O3 systems

Abstract A complete literature review, critical evaluation, and thermodynamic modeling of the phase diagrams and thermodynamic properties of all oxide phases in the binary systems B2O3 – SiO2 and B2O3 – Al2O3 have been performed. The molten oxide is described by the Modified Quasichemical Model. Discrepancies in the available experimental data have been resolved and an optimized set of self-consistent thermodynamic functions of all phases has been obtained. This thermodynamic database can be used with the FactSageTM thermodynamic computing system to calculate all thermodynamic properties and phase equilibria from 25 °C to above the liquidus temperatures at 1 atm of total pressure and over the entire composition range.

Spinosin, a C-glycoside flavonoid, enhances cognitive performance and adult hippocampal neurogenesis in mice.

Adult neurogenesis has received much attention due to its potential role in neurological or psychiatric disorders such as Alzheimers disease. In the present study, we examined whether spinosin, a C-glycoside flavonoid from the seeds of Zizyphus jujuba var. spinosa, affects cognitive performance and adult hippocampal neurogenesis in normal naïve mice. The subchronic administration of spinosin (5mg/kg) for 14days significantly increased the latency time in the passive avoidance task. Doublecortin and 5-bromo-2-deoxyuridine immunostaining revealed that the subchronic administration of spinosin (5mg/kg) significantly increased the proliferation and survival of neuronal cells and the number of immature neurons in the hippocampal dentate gyrus region. In addition, we observed an increase in the percentage of BrdU-incorporated cells co-localized with NeuN, a mature neuronal marker, which indicated that spinosin stimulates the differentiation of newly generated cells into mature neurons. Also, the subchronic treatment with spinosin (5mg/kg) increased the expression levels of phosphorylated extracellular-regulated kinase (ERK), phosphorylated cAMP response element-binding protein (CREB) and mature brain-derived neurotrophic factor (mBDNF) in the hippocampus. These findings demonstrate that spinosin has the potential for therapeutic use in treating the cognitive dysfunction observed in neurological or psychiatric disorders by up-regulating adult hippocampal neurogenesis or activating of the ERK-CREB-BDNF signaling pathway.