Yuan-Haun Lee

TOXICITY ASSESSMENT OF MONTMORILLONITE AS A DRUG CARRIER FOR PHARMACEUTICAL APPLICATIONS: YEAST AND RATS MODEL

Our previous study indicated that montmorillonite (MMT for short) was pharmaceutically feasible to be used as a carrier of an anticancer drug 5-FU. Emphasis of this study is thus placed on the toxicity of MMT to address whether it is clinically safe for practical use. Hematological data of rats model showed that the rats administered with oral MMT had significant increases in hemoglobin (Hb) concentration, Hamatocrit and RBC count than those of oral PBS buffer (p 0.05). Hematological analysis for intravenous injection also showed no statistically significant differences between experimental and control group (p>0.05). Biochemical analysis pointed out that compared to oral PBS there was not only a significant decrease of sodium (Na+) and chloride (Cl−) ion (p MMTK-SA ≫ MMT-SA > MMT according to EC0 or EC50 line. These all suggested that MMT alone is much less toxic than Lannate and potassium hexacyanoferrate(III). Apparently, it was concluded that MMT alone could be considered non-toxic to S. cerevisiae and Wistar rat for myriads of applications.

UNDERSTANDING THE CHARACTERISTICS OF L-ASCORBIC ACID-MONTMORILLONITE NANOCOMPOSITE: CHEMICAL STRUCTURE AND BIOTOXICITY

Following the previous study to intercalate a 5-fluorouracil (5-FU) into the interlayer spacing of montmorillonite (MMT) for colorectal cancer treatment, we selected a safe and non-pathological microorganism, Saccharomyces cerevisiae, as indicator microorganism to proceed risk assessment on MMT for feasibility study. Dose-response analysis from the perspective in toxicology was conducted to reveal the toxicity rankings of MMT, L-ascorbic acid (LAA) and montmorillonite-L-ascorbic acid (MMT-LAA) composites. This study also tended to intercalate LAA into MMT, observing chemical-structure stabilities of LAA-MMT composites. According to infrared spectroscopic analysis via FTIR, the lattice-vibration peaks of the distorted tetrahedron of SiO4 for MMT were ranged in 400-1200 cm−1. X-ray diffraction analysis also addressed the layer spacing changes in the MMT lattice with pH changes. The variation in the [001] d-spacing changed from 12.4 to 19.4 A with the increased pH, allowing higher intercalation of viable com...

Graphite with fullerene and filamentous carbon structures formed from iron melt as a lithium-intercalating anode

The electrochemical properties of flaky graphite containing carbon nanostructures, synthesized by a dissolution-precipitation method from a carbon-rich cast iron melt, were investigated. The formation of the highly crystalline graphite was realized at temperatures as low as 1600 °C. The presence of fullerenes and filamentous carbon structures on the graphite was confirmed by X-ray diffraction, Raman spectroscopy and scanning electron microscopy. The reversible lithium intercalation capacity of the graphitic product was more than 300 mAh/g. The first-cycle irreversible capacity was a mere 14%. The coulombic efficiency seemed to stabilize at values >99% from the fifth cycle.

Effect of atmosphere on decomposition of gadolinium-activated barium titanyl oxalate

Abstract The thermal decomposition of Gd-activated barium titanyl oxalate (BaTiO(C2O4)2-4H2O) is investigated by using differential thermal analysis in air and N2 under various O2 partial pressures. As a result, it indicates that the decomposition temperature is reduced with the addition of Gd+3. The Gd-added precipitated oxalate decomposition allows the reaction to occur at a lower O2 partial pressure than that of the precipitated oxalate decomposition with no addition of Gd+3.

Oxygen-induced structural change of zirconia by adding rare earth oxides with solid state method

Abstract The crystal structures of zirconia by doping such rare earth oxides, as Pr 2 O 3 , Nd 2 O 3 , Sm 2 O 3 , Dy 2 O 3 , Ho 2 O 3 and Yb 2 O 3 (RO 1.5 ), were obtained by using powder X-ray diffraction method. These ZrO 2 -RO 1.5 samples were prepared by solid state reaction methods. The existing regions of stabilized zirconia were strongly influenced by the species and contents of dopants. The lattice parameters of the cubic phases were dependent on the contents of dopants, and the differential of lattice parameters corresponds to the ionic radii of dopant. The density of the three phases of zirconia revealed a linear relation with the contents of dopants, and the slopes of the density of three phases in each system ZrO 2 -RO 1.5 also indicated linear relations with atomic weight of R 3+ ion.

Electronic behavior of Li—GIC in the lithium secondary battery

Abstract Composite materials which, when mixing graphite with montmorillonite and TEF oligomer, can replace lithium metal as the negative electrode materials for the lithium secondary batteries have been studied. The anode composite materials were fabricated by mixing graphite with different components of montmorillonite and TFE oligomer, ever lithium fluoride. The microstructure of the anodic composite materials were characterized by X-ray diffraction and its data was refined with the Rietveld analysis. The electric properties of the composite materials were characterized by electrochemical impedance spectroscopy (EIS). The electrochemical behaviours of the composite materials were investigated in a 1 M LiPF6 solution with a 50:50 mixture of ethylene carbonate (EC) and diethylene carbonate (DEC). In our previous study, with the increased graphitization of the graphite materials, the layer structure became more orderly and the discharge capacity higher, however, the electronic behavior of Li—GIC, as a composite material mixed with montmorillonite intercalated by TEF oligomer, became complicated in this case. From the cycle voltammetry, with the increasing of potential sweeping rate, the anodic peak would shift to the higher potential and show a larger current. The relationship between the component of anode composite materials and its intercalation as the result of the electrochemical behaviors will be discussed.

CYTOTOXIC ASSESSMENT OF L-ASCORBIC ACID/MONTMORILLONITE UPON HUMAN DERMAL FIBROBLASTS IN VITRO: MTT ACTIVITY ASSAY

This first-attempt study tended to inspect the cytotoxic effects of montmorillonite (MMT) or 0.01 N phosphoric acid treated MMT supplemented with L-ascorbic acid (LAA) upon human dermal fibroblasts for possible applications. Light micrographs of human dermal fibroblast cell cultures revealed that more dense black spots in larger sizes were observed when higher levels of MMT were supplemented into the fibroblast culture, indicating that more dermal fibroblasts were covered by MMT particles. Compared with the supplementation of LAA alone, this study selected mitochondrial dehydrogenase activity (MTT) assay as an indicator bioreaction to show possible cytotoxic (or allergic) responses upon human dermal fibroblasts in vitro when LAA/acid-treated MMT composites were added. Statistical analysis showed that LAA augmented with either MMT or 0.01 N phosphoric-acid-treated MMT provoked insignificant cytotoxic responses to human dermal fibroblasts. Thus, an augmentation of MMT or 0.01 N phosphoric-acid-treated MMT t...

ASSESSMENT UPON CHARACTERISTICS OF CONSTRUCTED L-ASCORBIC ACID/MONTMORILLONITE COMPOSITE

This study constructs new L-ascorbic acid (LAA) composites in low toxicity and high stability for feasible application. Although literature reveals that sodium thiosulphate could stabilize the activity of LAA, our findings show that the significant toxicity was provoked by sodium thiosulphate. A safe and non-toxic material montmorillonite (MMT) was thus used to attenuate this toxicity and to sustain the stability of composites with economic feasibility for practical use. As the proton released from LAA promots the increases of interlayer spacing of clay layers in MMT, the formation of stable and safe LAA composites resulted. The most feasible were found to be the composites [MMT + 10% LAA + 0.90% Na2S2O3] and [MMT + 5% LAA + 1.35% Na2S2O3].

Performance Study of Carbon Coating on Si/Graphite Composites for Lithium Ion Battery Anode Materials

The composites which contain silicon and natural graphite embedded in pyrolyzed carbon have been synthesized and investigated as anode material for lithium ion secondary batteries. Carbon coated onto silicon/graphite composites by using a pyrolysis reaction of phenolic resin at 1300℃. The pyrolyzed carbon was used as a buffer material and binder for silicon/graphite composites. As a result, the irreversibility and capacity decay were obviously improved with increasing amount of phenolic resin. A composite containing 45wt% phenolic resin, 45wt% graphite and 10wt% silicon exhibited a stable capacity of 443 mAh/g and better cycling performance.

SUPERLATTICE REFLECTIONS FROM (La1-xSrx)2CuO4 AND ITS DETECTION BY X-RAY POWDER DIFFRACTION

Oxygen defects have usually had a very large negative effect on superconductivity, like(La1−xSrx)2CuO4 It is considered that its transformation related to temperatures with increasing oxygen defects. This system undergoes two-step phase transformations from a tetragonal phase to an orthorhombic phase upon cooling over the range of composition 0.025<x<0.10. A firing procedure without put the sample into pellet made it become abnormal by X-ray diffraction, just like a superlattice reflections from oxide compounds in the range of composition as mentioned above. The weak superlattice reflections are tried to be indexed consistently with the superstructure by the Rietveld refinement method. The tilted form in the lower symmetry or more distorted form in polyhedral tilt transitions was demonstrated with the calculated data refined from the measured X-ray diffraction intensities. [Keyword: X-ray Diffraction, Rietveld Analysis, Superlattice, Superconductor, Microstructure, Polyhedral Tilting.]