White and black deposits have been frequently observed on the surface of Korean stone cultural heritages, and they are considered as damage factors in both conservation and esthetic points of view. In order to set up the appropriate conservation remedy, it is important to know their origins, characteristics, and compositions. In this study, optical and scanning electron microscopes (SEMs) equipped with an energy-dispersive spectrometer (EDS) and X-ray diffractometer were employed to determine the white and black deposits. It was found that both deposits consisted mainly of calcium carbonate (calcite) and calcium sulfate (gypsum). The calcite and gypsum were characterized by bladed, rhombohedral, tabular, and amorphous morphologies under a SEM. The black deposit was not only composed of calcite or gypsum, but also accompanied amorphous and irregular matrix. SEM-EDS analysis revealed an abundance of silicon, aluminum, iron, phosphorus, and carbon on the matrix, which were major elements of soil, atmospheric deposits, and organisms. The white deposit, on the other hand, barely contained those coloring substances. These salts and deposited substances were caused by chemical reaction and physical adhesion between rock-forming minerals, lime mortar, sulfur in polluted air environment, soil dust, and microorganisms.

We evaluated the effects of the two main kiwifruit cultivars (gold kiwifruit (GOK) and green kiwifruit (GRK)) and their active phenolic compound, quercetin, on H2O2-induced inhibition of gap-junction intercellular communication (GJIC) in WB-F344 rat liver epithelial cells. We found that both GOK and GRK protect WB-F344 cells from H2O2-induced inhibition of GJIC. The extracellular signal-regulated protein kinase 1/2 (ERK1/2)–connexin 43 (Cx43) signalling pathway is crucial for the regulation of GJIC, and both GOK and GRK blocked the H2O2-induced phosphorylation of Cx43 and ERK1/2 in WB-F344 cells. Quercetin alone attenuated the H2O2-mediated ERK1/2–Cx43 signalling pathway and consequently reversed H2O2-mediated inhibition of GJIC in WB-F344 cells. A free radical-scavenging assay using 1,1-diphenyl-2-picrylhydrazyl showed that the scavenging activity of quercetin was higher than that of a synthetic antioxidant, butylated hydroxytoluene, per mol, suggesting that the chemopreventive effect of quercetin on H2O2-mediated inhibition of ERK1/2–Cx43 signalling and GJIC may be mediated through its free radical-scavenging activity. Since the carcinogenicity of reactive oxygen species such as H2O2 is attributable to the inhibition of GJIC, GOK, GRK and quercetin may have chemopreventive potential by preventing the inhibition of GJIC.

This study was conducted to examine the effect of energy substrates in a serum-free culture medium on in vitro development of porcine embryos. Presumptive zygotes derived from in vitro fertilization were cultured in glucose-free North Carolina State University (NCSU)-23 medium with glucose, pyruvate, fructose and lactate added to the culture medium singly or in various combinations. In experiment 1, a higher percentage of embryos cleaved (53–63% vs 10–13%) and developed to the blastocyst stage (18–27% vs 0) after the single addition of glucose (5.6 mM), pyruvate (0.5 mM) or lactate (10 mM) than with no energy substrate addition or the addition only of fructose (5.6 mM). In experiment 2, the addition of pyruvate and lactate resulted in higher blastocyst formation (25%) than other combinations (6–22%), while the addition of glucose and pyruvate significantly inhibited blastocyst formation. Increasing lactate concentration, as a single energy supplement, from 5 to 20 mM significantly improved blastocyst formation (7% vs 14–18%), while no benefit was achieved from increasing pyruvate concentration up to 2 mM (experiment 3). Glucose-free NCSU-23 medium supplemented with 0.5 mM pyruvate and 5 mM lactate significantly improved blastocyst formation (28% vs 17%) compared with NCSU-23 medium supplemented with 5.6 mM glucose (experiment 4). In conclusion, pyruvate and lactate are preferable energy substrates to support in vitro development of porcine embryos cultured in a serum-free NCSU-23 medium.

The effect of Mg in Ag(Mg)/SiO2/Si multilayers on the adhesion, passivation, and resistivity following vacuum annealing at 200–500 °C has been investigated. The annealing of Ag(Mg)/SiO2/Si multilayers produced surface and interfacial MgO layers, resulting in a MgO/Ag/MgO/SiO2/Si structure. The formation of a surface MgO/Ag bilayer structure provided excellent passivation against air and CF4 plasma chemistry. In addition, the adhesion of Ag to SiO2 was improved due to the formation of an interfacial MgO layer resulting from the reaction of segregated Mg with SiO2. However, the negligible solubility of Si in Ag prevented the dissolution of free silicon into the Ag(Mg) film produced from the reaction Mg + SiO2 = MgO + free Si, which in turn limited the reaction between Mg and SiO2, which led to a decrease in the adhesion of Ag to SiO2 at the higher temperature. The use of an O2 plasma prior to Ag(Mg) alloy deposition on SiO2 produced an oxygen-rich surface on the SiO2, which allowed for the enhanced reaction of the segregated Mg and SiO2 at the surface, thus resulting in markedly increased adhesion properties.

In this study, Ir/IrO2 mixture electrodes are fabricated by furnace oxidation of sputter deposited Ir, IrO2 and their hybrid electrodes. The characteristics of furnace oxidation of various electrode stems with Ir family and their limitation are investigated. Annealing at higher than 700°C oxidation results in formation of undesirable extrusions in Ir electrode. When the Ir oxide facet extrusions are formed, Ir near at the extrusion is used up and SiO2 substrate are exposed. In addition, furnace oxidized Ir/Ti electrode is suggested as an alternative electrode, which shows smooth surface, good thermal stability, high oxygen contents and low resistivity.

A PZT thin film capacitor displays a reduction in the charge storage density (Qc') after the device has undergone pulsed electrical stress. This changes the charge-voltage relationship for the devices. The effect of this change in the Q-V relationship on the DRAM READ time is described. Measurements of the charge and voltage decay rates have been previously identified as ideal techniques for characterizing signal loss. For the first time the effects of electrical stress on these rates have been studied. While the charge decay rate decreases with an increase in the number of stress cycles for both the bipolar and unipolar stress, the voltage decay rate decreases after unipolar stress but it increases for bipolar stress at lower stress voltages. The implications of these results on the DRAM performance shall be discussed.

The effects of electron beam irradiation on the electrical characteristics of Pt-PZT-Pt and Pt-PLZT-Pt (with La concentration of 5% and 10%) thin film capacitors were studied. The top electrode of each capacitor was bombarded by localized energetic electrons with incident energies varying from 5 keV to 25 ke.V. Large distortions in the hysteresis loops were observed when the incident electrons had enough energy to penetrate the 1000Å Pt top electrode. The damage effects are strongly dependent on the original domain orientation when the film is irradiated, and an applied a.c. field after the irradiation seems to induce some recovery effects. The damage mechanism is explained by a simple model which considers the effect of space charge fields generated by the charge carriers trapped at the domain boundaries.

The effects of the microstructure of PZT sol-gel thin films, processed using different solutions, on their material and electrical properties have been studied. The films have different degrees of preferred orientation of the perovskite crystals as well as different grain size. The material characteristics are evaluated using SEM micrographs and XRD. Correlation of these material properties with the electrical properties for both NVRAM and DRAM applications is made.

In this work, a high-temperature deposition technique has been developed for ultra-thin sputtered PZT films for ULSI DRAM (<256Mb) storage capacitor applications. In contrast to the previously developed low-temperature (200°C) deposition, deposition at high-temperature (400°C) yields a desirable reduction in grain size of the perovskite phase. The thickness of PZT films has been reduced to less than 30nm with high charge storage density (∼30μC/cm2) and low leakage current density. An optimized 65nm PZT thin film was found to have an equivalent SiO2 thickness of 1.9Å and a leakage current density of less than 10−6 A/cm2 under 2V operation.

The origin and the effects of asymmetrical electrical behavior in sputtered PZT (Zr/Ti=65/35) thin film capacitors with Pt electrodes have been studied. The asymmetry and constriction in the P-E hysteresis loops are understood to result from differences in mechanical stress at the top and bottom PZT/Pt interfaces because they experience different thermal cycles during fabrication. A method for correctly positioning asymmetric loops on the polarization axis is suggested. Both d.c. and a.c. electrical stressing (of either polarity) lead to hysteresis relaxation and symmetrization. A post-processing anneal leads to electrically symmetrical devices.

The feasibility of the fabrication of thin film capacitors of Lead Zirconate Titanate (PZT) by reactive DC-Magnetron sputtering, with large switched charge and low leakage current densities for ultra-large scale integration Dynamic Random Access Memory (ULSI DRAM) applications has been demonstrated. As-deposited films were found to be predominantly pyrochlore; therefore, a subsequent phase transformation-inducing thermal processing step was key to obtaining device quality films. The importance of the thermal budget in optimizing the device characteristics of PZT films is discussed. The importance of the role of Pb compensation in lowering the required thermal budget and significantly enhancing device characteristics is shown.

The Pt-Lead Zirconate Titanate (PZT) thin film interface plays a key role in determining the electrical properties and phase transformation kinetics of Pt-PZT-Pt thin film capacitor structures. The results of the electrical and material properties of PZT (65/35) films that vary in thickness between 500 Å to 4000 Å deposited by DC-magnetron sputtering under identical deposition conditions, and subjected to the same post-deposition thermal processing conditions shows that the Pt-PZT interface dominates thin film properties at low thicknesses (≦ 2000 Å). The charge storage density (Qc') and maximum polarization (Pmax) shows an anomalous variation with thickness, showing an initial increase followed by a drastic decrease as the film thickness is scaled down to 500Å. Significant interdiffusion at the PZT film-Pt electrode retards the pyrochlore-to-perovskite phase transformation nucleation and growth rate in PZT films of thickness 2000Å and lower. Gate polarity dependence of the time-tobreakdown and the degradation field is observed for all PZT film thicknesses (including 4000Å). This indicates that the ferroelectric film-electrode interface has an important role to play in determining the electrical reliability properties even in the 4000Å thick PZT film, although Qc' and Pmax are not adversely affected at these thicknesses.