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Background/purpose In this study, we investigated the relative contributions of design factors to the fracture strength of provisional materials after repair. Materials and methods The Taguchi method was used to investigate the optimal design with respect to four different design factors: subject material, repair material, repair design, and connector thickness. Each factor was assigned three levels. Using the Taguchi L 9 orthogonal array, nine rectangular bar-shaped experimental specimens with different parameter combinations were fabricated ( n = 5) and tested with a three-point bending test. The fracture load (in newtons) of each specimen group was recorded. The Taguchi method was employed to identify the significance of each design factor in controlling the fracture strength. The sensitivity of each design parameter was determined using an analysis of variance. Fractographic analysis was performed to identify the adhesive or cohesive failure mode for each specimen. Results The mean effect of the design factors at each level was determined. The subject material, with a contribution percentage of as high as 33.48%, had the most dominant effect on the fracture strength of the repaired provisional restorations, followed by the repair material (31.88%), connector thickness (19.70%), and joint design (14.94%). The strongest subject material was bis-acryl Protemp 3 Garant. The polymethyl methacry late material, Tempron, was the preferred repair material. A 4-mm connector thickness was the best level. A 45o bevel joint was superior to the butt or fiber joint. The predicted fracture strength of the optimum parameter combination (Protemp 3 Garant/45o bevel joint/Tempron/4 mm connector thickness) was 173.34 N. From the fractographic analysis, different bonding abilities between the same and different resin materials were investigated. Fiber joint groups were nearly all in the cohesive mode without complete catastrophic fracture. Conclusion Within the limitations of this study, these four design factors had different contributions to the fracture strength of repaired provisional restorations. Clinicians must be aware of the sequence of importance in determining better problem-solving methods.

This paper presents the design of a non-inverting synchronous buck-boost DC/DC power converter with moderate power level for a solar power management system. The buck-boost requirement arises from the rapid changes in the atmospheric condition or the sunlight incident angle. The system mainly consists of the non-inverting synchronous buck-boost DC/DC power converter, MOSFET drivers, anti-cross conduction logic circuitry, feedback compensator, and PWM regulator. The system is capable of converting the supply voltage source to higher and lower voltages to the load terminal with voltage polarity unchanged. The voltage at the load terminal is controlled by continuously adjusting the duty cycle of the PWM regulator. Application of the buck-boost converter in battery management system design is also addressed.

A full-duplex CATV/wireless-over-fiber lightwave transmission system consisting of one broadband light source (BLS), two optical interleavers (ILs), one intensity modulator, and one phase modulator is proposed and experimentally demonstrated. The downstream light is optically promoted from 10Gbps/25GHz microwave (MW) data signal to 10Gbps/100GHz and 10Gbps/50GHz millimeter-wave (MMW) data signals in fiber-wireless convergence, and intensity-modulated with 50-550 MHz CATV signal. For up-link transmission, the downstream light is phase-remodulated with 10Gbps/25GHz MW data signal in fiber-wireless convergence. Over a 40-km single-mode fiber (SMF) and a 10-m radio frequency (RF) wireless transport, bit error rate (BER), carrier-to-noise ratio (CNR), composite second-order (CSO), and composite triple-beat (CTB) are observed to perform well in such full-duplex CATV/wireless-over-fiber lightwave transmission systems. This full-duplex 100-GHz/50-GHz/25-GHz/550-MHz lightwave transmission system is an attractive alternative. This transmission system not only presents its advancement in the integration of fiber backbone and CATV/wireless feeder networks, but also it provides the advantages of a communication channel for higher data rates and bandwidth.

This paper presents the stability analysis of a non-inverting synchronous buck-boost DC/DC power converter for a solar power management system. The system can operate in buck, buck-boost or boost mode according to the condition of the supply voltage. The variation of the supply voltage arises from the rapid changes of the atmospheric condition or sunlight incident angle. The stability margins of each individual operation mode for different system parameters (inductor, capacitor) and load conditions are analyzed first. The results show that the stability margins depend on the inductor and capacitor selected for the converter and depend on the load conditions also. The systems are then modeled as Markov jump systems for evaluating the mean square stability of the systems. With careful selection of the system parameters, adequate stability margins of each individual operation mode and mean square stability of the jump system can be assured. The buck-boost converter is incorporated into the solar power battery management system to maximize the utility of the available solar power drawn from the solar panel.

Pyridostigmine bromide (PB), a highly hygroscopic drug was selected as the model drug. A sustained-release (SR) tablet prepared by direct compression of wet-extruded and spheronized core pellets with HPMC excipients and exhibited a zero-order sustained release (SR) profile. The 2(3) full factorial design was utilized to search an optimal SR tablet formulation. This optimal formulation was followed zero-order mechanism and had specific release rate at different time intervals (released % of 1, 6, and 12 hr were 15.84, 58.56, and 93.10%). The results of moisture absorption by Karl Fischer meter showed the optimum SR tablet could improve the hygroscopic defect of the pure drug (PB). In the in vivo study, the results of the bioavailability data showed the T(max) was prolonged (from 0.65 +/- 0.082 hr to 4.83 +/- 1.60 hr) and AUC(0-t) (from 734.88 +/- 230.68 ng/ml.hr to 1153.34 +/- 488.08 ng/ml.hr) and was increased respectively for optimum PB-SR tablets when compared with commercial immediate release (IR) tablets. Furthermore, the percentages of in vitro dissolution and in vivo absorption in the rabbits have good correlation. We believe that PB-SR tablets designed in our study would improve defects of PB, decrease the frequency of administration and enhance the retention period of drug efficacy in vivo for personnel exposed to contamination situations in war or terrorist attacks in the future.

Pyridostigmine bromide (PB) sustained-release (SR) pellets were developed by extrusion-spheronization and fluid-bed methods using Taguchi experimental and 2(3) full factorial design. In vitro studies, the 2(3) full factorial design was utilized to search for the optimal SR pellets with specific release rate at different time intervals (release percent of 2, 6, 12, and 24 hr were 6.24, 33.48, 75.18, and 95.26%, respectively) which followed a zero-order mechanism (n=0.93). The results of moisture absorption by Karl Fischer has shown the optimum SR pellets at 25 degrees C/60% RH, 30 degrees C/65% RH, and 40 degrees C/75% RH chambers from 1 hr-4 weeks, attributing that the moisture absorption was not significantly increased. In the in vivo study, the results of the bioavailability data showed the Tmax (from 0.65+/-0.082 hr-4.82+/-2.12 hr) and AUC0-30 hr (from 734.88+/-230.68 ng/mL.hr-1454.86+/-319.28 ng/mL.hr) were prolonged and increased, as well as Cmax (from 251.87+/-27.51 ng/mL-115.08+/-14.87 ng/mL) was decreased for optimum SR-PB pellets when compared with commercial immediate-release (IR) tablets. Furthermore, a good linear regression relationship (r=0.9943) was observed between the fraction dissolution and fraction absorption for the optimum SR pellets. In this study, the formulation design not only improved the hygroscopic character of PB but also achieved the SR effect.

Pyridostigmine bromide (PB) is a reversible acetylcholinesterase inhibitor that has been used as a pretreatment drug for "Soman" nerve gas poisoning in combat to increase survival. The once-daily PB-sustained-release (SR) pellets were developed by extrusion-spheronization and fluid-bed methods in our laboratory, which was followed by zero-order release mechanism. The results showed that the released concentration of acetylcholine (ACh) in skeletal muscle and the released concentration of protein unbound drug in blood were determined by microdialysis technique to have significant differences (P