Advanced Materials Research Vols. 378-379

Abstract: Density of states in the channel bulk area of a-Si:H thin-film transistors (TFTs) was extracted by using low-frequency noise analysis. The drain current noise power spectral density shows 1/ƒγ behavior at relatively high frequencies (ƒ > 1 kHz), which is due to the exponential distribution of tail states. For the analysis, the modified number fluctuation model which is correlated with mobility fluctuation was used. From the relationship (γ=1- kT/Et ) between exponent γ and the slope of exponential distribution Et of band tail states, the distribution of the band tail near conduction band was extracted.

Abstract: This article utilities ocean battery drive LED lamp which is a symbol of NTOU. One of the renewable green energy is sea water existing by the nature. The sea water battery has convenience of usage and storage. LEDs will be a great benefit to the saving-energy and environmental protection in the lighting lamps region. When we consider that the choice for providing power type, origin and green, the ocean battery may offer the electric power of Direct Current (D.C.) for a long time which causing it unexpected deficient and does not cause the marine pollution. There are two experiments respectively to analyze that how long time the ocean battery can consume and these characteristics. One is to have the loading resistance 2.95 KΩ in order to form the circuit, lets the ocean battery discharge continually, each process 10 minutes later, gauges its voltage; Another lets the ocean battery itself nature electric discharge, uses the tri-ammeter to gauge the ocean battery voltage. Then we design a LED chart for NTOU fonts having dimensions of 2000 x 10 x 5 mm3 composing the soft LED lamp strip which weld them on the aluminum based plate as indicative lamp in the night navigation. The starting minimum voltage is 5 V and the maximum voltage is 12 V. The results show that so long as the ocean battery vibrates light flipping, the voltage starts unstable, will draw steady-state value after a few time. In other words, the air bubble will affect the voltage value in the ocean battery; therefore we must pay attention to solve this question.

Abstract: The aim of this study is to investigate effect of Cu and Co additions on corrosion behavior of NiTi shape memory alloys for orthodontic application. Ni50.6Ti49.4, Ti49Ni46Cu5 and Ti50Ni47Co3 (at%) alloys were prepared. The specimens were melted by arc-melting furnace and homogenized at 800oC for 3.6 ks. Transformation temperatures were analyzed by differential scanning calorimeter (DSC). The corrosion behavior was assessed electrochemically in artificial saliva (pH 5.35) at 37oC. Open circuit potential (OCP) was monitored 3.6 ks followed by potentiodynamic techniques. The results show that all of specimens revealed transformation temperature close to oral temperature which may be utilized as orthodontic wire. Surface roughness was measured in order to ensure that there is no significant difference which might affect corrosion resistance. It is seen that by adding Co and Cu into NiTi alloys, the corrosion potential (Ecorr) and pitting corrosion potential (Ebreak) increase resulting in lower corrosion rate. Conceivably, Co and Cu additions considerable affect the corrosion behavior of NiTi alloys by improving corrosion resistance in artificial saliva.

Abstract: This paper presents a low-power multistage amplifier with a novel capacitor-multiplier frequency compensation (CMFC) technique. The proposed compensation strategy can allow the circuit to occupy less silicon area and to drive large capacitive loads more effectively. Moreover, smaller physical capacitance results in higher gain-bandwidth product (GBW) and improved transient responses. Furthermore, the capacitor multiplier stage (CMS) embedded in CMFC creates a left-half plane (LHP) zero, which boosts the phase margin and enhances the stability of the amplifier. Implemented in a commercial 0.5-μm CMOS technology and driving 500pF capacitive load, a three-stage CMFC amplifier achieves over 120dB gain, 1.699MHz GBW and 1.625V/μS average slew rate, while only dissipating 330μW under 3.3V supply.

Abstract: Electrostatic potential and electrostatic discharge (ESD) has been a factory issue for years, not only limited to semiconductor-based electronic devices, but there are evidences that new devices from emerging technologies become sensitive which are MEMS and NEMS. This paper describes new electrostatic control and device handling solutions for critical electrostatic control environment for MEMS manufacturing processes. There are experiments of personnel grounding devices, device handling materials, and evaluation of static control surfaces.

Abstract: This paper presents the simulation model of Dual Magnetodiode and Dual Schottky Magnetodiode using Sentaurus TCAD to simulate the virtual structure of magneto device and apply Hall Effect to measure magnetic field response of the device. Firstly, we use the program to simulate the magnetodiode with p-type semiconductor and aluminum anode and measure electrical properties and magnetic field sensitivity. Simulation results show that sensitivity of Dual Schottky magnetodiode is higher than that of Dual magnetodiode.

Abstract: Natural rubber latex products are used as orthodontic elastics but the increased incidence of latex allergies has led to the development of nonlatex orthodontic products. In Thailand, commercial nonlatex orthodontic elastics are not readily available and the cost of imported non latex products is relatively high. Thai non latex elasticshave been developedas alternative orthodontic products for latex-allergic patients and their costs are affordable.Objective: Tocomparethe mechanical properties of Thai nonlatex elastics with commercial natural latex orthodontic elastics for orthodontic application. Materials and Methods: Samples of imported latex orthodontic elastics [Ormco(USA), G&H (USA), Creative Orthodontics (China), Tomy Elastics (Japan)]were selected to compare their dimensional characteristics and mechanical properties with Thai non latex elastics. The dimensional characteristics of the elastics (i.e., inner diameter, cross-sectional thickness and cross-sectional area) were determined and their mechanical properties [(i.e., initial extension force (F0), 24 h- residual force (F24), percentage of force loss, force exerted at 3x the specified inner diameter(F3xID) and breaking force] were tested next. The data were analyzed with One-way ANOVA and multiple comparison by Tukey’s test was used among groups (p<0.05). Results:Significant differences of dimensional characteristics and mechanical properties were found among each brand of elastics. Thai non latex elastics had significantly different mechanical properties from natural latex elastics as reported in previous studies(p<0.05). Thai non latex elastics had the lowest initial extension force (0.82N), 24-h residual force (0.56 N) and breaking force (19.63 N, 8.183 MPa) but the highest percentage of force loss after 24 h (32.62%).However, the percentage of force loss was higher than commercial non latexelastics as previously reported. Conclusion:Thai nonlatex elastics were not comparable to those of the latex elasticsregardingmechanical properties;however,these are acceptable for orthodontic application. Therefore, the clinical selection of elastics should be based on the patient’s medical history and the specific mechanical properties of the type of elastic. Thai nonlatex orthodontic elastics can be a valid alternativefor patients with latex allergy in Thailand and this study contributes to the continuous development of Thai nonlatex orthodontic elastics.

Abstract: Objectives:The study aimed to compare the residual forceoflocally produced Thai orthodontic elastomeric ligatureswith 2 commercial brands.Materials and Methods: The study compared Thai clear and blue orthodontic elastomeric ligatures with clear and blue commercial brands[Unitek (USA) and W&H (China)]. The dimensional characteristics of the ligatures (i.e., inner diameter, outer diameter and cross-section thickness) were measured. Then initial extension force was measured. After that, the residual force was determined at day 1and repeated on day 2,3,4,5,6,7,14,21, and 28 andthe percentage of residual force wascalculatedaccording to ISO 21606:2007. The data were analyzed with Two-way ANOVA and multiple linear regression (p<0.05). Results: Thai ligatures had significantly greater inner diameter(clear 1.22 mm, blue 1.21 mm) and cross-section thickness (clear 0.78 mm, blue 0.79 mm) in both colors when compared with Unitek and W&H brands. Thai ligatures had no significant difference in cross-section thickness between clear and blue.Thai clear ligatures hadthe highest initial extension force(2.30 N). Thai ligatures showed similar force decay patterns as other brands, rapidly decreasing the first day, gradually decreasing over 7 days and remaining nearly constant until 28 days.However, both clear and blue Thai elastomeric ligatures had significantly less outer diameters (clear 3.12 mm, blue 3.15mm). Thai blue ligatures had the lowest initial extension force (1.96 N).TheThai clear and blue demonstrated less percentage of residual force in the first day (clear 53.00%, blue 50.66%) and28 days (clear, 37.69%, blue, 37.00%) butthey were clinically acceptable. In general, clear ligatures exhibited a greater percentage of residual force than blue ligatureamong the 3 brands. Conclusion:Thai orthodontic elastomeric ligature properties are comparable to commercially available brands and acceptable for clinical application.

Abstract: Objective: This study aimed to investigate fluoride release, flexural strength and surface characteristics of three orthodontic acrylic resins (A) blended with (1) sodium fluoride powder (NaF), (2) calcium fluoride powder (CaF2), and (3) glass ionomer cement powder (GIC). Material & Methods: Acrylic resin was blended with NaF, CaF2 , and GIC to make orthodontic acrylic plates. Each sample group was divided into subgroups at fluoride concentrations 5%, 10% and 20%. The acrylic resin was cured in a round stainless steel mold and kept in a bottle with 10 ml. deionized water then kept in an incubator at 37oC. The deionized water, changed every day, was tested for fluoride release up to six mo by Orion machine. For the flexural strength test, the samples were cured in a stainless steel mold, 64 mm. long, 10 mm. wide and 3.3 mm. high according to standard of ISO 20795-2 and testing was done up to 6 mo in deionized water. Scanning electron microscope determined surface characteristics after being blended. Results: Fluoride release was observed from orthodontic acrylic plates blended with NaF, CaF2 and GIC. The results of the A-NaF and the A- CaF2 group decreased fluoride level greatly at day 2, but the A-GIC group was observed at day 7. The A-NaF group and the A-GIC group could not detect fluoride level after mo 4 and 2, respectively. The A-CaF2 group found greater long term fluoride release than the A-NaF and the A-GIC group especially at 20% concentration (up to six mo). Significant differences (p<0.05) of fluoride release level (ppmF) among the A-NaF, A-GIC, and A-CaF2 groups at 5% concentration in every time point from day 1 to the mo 5, but not significant in mo 6 similar to the 10% concentration comparison. Whereas, comparing the 20% concentration among groups, significant differences (p<0.05) were found between groups in all periods of time (from the day 1 to mo 6). When comparing the different concentrations of 5%, 10%, and 20% in each group, significant differences (p<0.05) were found in every concentration at every time period of the A-GIC group from day 1 to mo 2, in the A-CaF2 group from day 1 to mo 6 and in the A-NaF group from day 1 to mo 4. Conclusion: Fluoride release was observed from orthodontic acrylic plates blended with NaF, CaF2 and GIC. The longest duration of fluoride release from orthodontic acrylic plates was found in the CaF2 group followed by the NaF and GIC groups. The flexural strength in every group decreased over time. This result implied that the flexural strength decreased during fluoride release. The acrylic surface was seen to be porous in every period of the fluoride release process.

Abstract: The effect of iron doping on physical and chemical properties of activated carbon, the effect of initial concentration and temperature on adsorption behavior of adsorbents for aniline from water, and adsorption equilibrium and thermodynamics were investigated. The results show that Fe doping obviously increase acidic oxygen-containg groups of activated carbon surface. Effect of Fe doping on adsorption capacity of aniline at the low concentration is insignificant. Equilibrium adsorption uptake decreases with an increase in adsorption temperaure. Freundlich model can better describe adsorption behavior of aniline on AC and Fe/AC. Aniline adsorption is spontaneous and exothermic.