Antioxidant activities of red pepper (Capsicum annuum) pericarp and seed extracts

In this study, we examined the antioxidant activities of red pepper (Capsicum annuum, L.) pericarp and red pepper seed extracts. The extracts were evaluated by various antioxidant assays, including 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging, superoxide anion radical scavenging, hydroxyl radical scavenging, [2,2′‐azino‐bis(3‐ethylbenzthiazoline‐6‐sulphonic acid)] (ABTS) radical scavenging, ferrous chelating activity, superoxide dismutase (SOD) activity and reducing power, along with the determination of total phenolic and flavonoid contents. All the extracts showed strong antioxidant activity by the testing methods. The red pepper pericarp extract exhibited strong ferrous chelating activity and high scavenging activity against free radicals, including both the hydroxyl and DPPH radicals, but it exhibited weaker scavenging activity for the superoxide anion radical and for SOD. In contrast, the red pepper seed extract exhibited strong SOD activity and high scavenging activity against the superoxide anion radical, but showed weaker ferrous chelating activity, hydroxyl radical scavenging, and DPPH radical scavenging. We observed that the reducing power level and ABTS radical scavenging activity of the red pepper seed were higher than those of the red pepper pericarp at the highest tested concentration. Most of the test results for the red pepper seed and red pepper pericarp extracts increased markedly with increasing concentration; however, the metal chelating, SOD and ABTS radical scavenging activities did not increase with the concentration. Highest total phenolic and flavonoid contents were obtained from the red pepper pericarp extracts. Overall, the red pepper seed and red pepper pericarp extracts were highly effective for the antioxidant properties assayed, with the exceptions of ferrous chelating activity, hydroxyl radical scavenging and SOD activity.     

A study on improvement of sodium cooled TRU burner design using burnable poison

A new design approach to improve safety characteristics of sodium cooled core for transuranic element transmutation is discussed. In the new option, some amount of fertile material is removed for reduction of sodium void reactivity. Simultaneously, a burnable absorber material is loaded in replacement of fertile material to compensate for reactivity drop during the fuel depletion. Two methods of burnable absorber loading are considered such as the homogeneous and the heterogeneous. In the results, it is found that the homogeneous loading cannot reduce the sodium void reactivity but makes the reactivity more positive. On the other hand, the heterogeneous loading can reduce the sodium void reactivity successfully. It is also found that the increment in burnup reactivity swing is negligible when the burnable poison is heterogeneously loaded. It is concluded that if the burnable poison material is loaded appropriately, the sodium void reactivity can be reduced without any significant penalty of increase in burnup reactivity swing.     

Magnetorheological finishing process for hard materials using sintered iron-CNT compound abrasives

The use of magnetorheological fluids for finishing is one of the most promising smart processes for the fabrication of ultra-fine surfaces, particularly three-dimensional millimeter or micrometer structures. This process is not readily applicable to hard-surface materials, like an Al₂O₃–TiC hard disk slider, if a conventional rotating tool is used. This is due to the rotational speed and the resulting actual impressed abrasion energy limits, and the consequent low efficiency of the material removal rate. In this study, the main mechanism responsible for the decrease of the material removal rate on hard materials for a wheel-type magnetorheological finishing process is examined, both theoretically and experimentally, and a solution to this problem is devised via two approaches. The first uses a rectilinear alternating motion to improve processing conditions, and the second focuses on the use of more effective abrasives, namely magnetizable abrasives made of iron powders sintered with carbon nanotubes, which are new abrasives that have not yet been introduced in the field of surface finishing. Furthermore, it is shown that these abrasives increase the lifetime of consumables (magnetorheological fluid and abrasives) and the material removal rate.     

Wirelessly Synchronized One‐Way Ranging Algorithm with Active Mobile Nodes

In this letter, we propose a one‐way ranging algorithm that is based on wireless synchronization with measured timestamps and clock frequency offsets. In our proposed algorithm, an active mobile node initiates a ranging procedure by transmitting a ranging frame, and the anchor nodes report their timestamps for the received ranging frame to a reference anchor node. The synchronization of a pair of nodes is provided with instantaneous time information, and the corresponding difference of distances can be calculated.     

Learning Behaviors of Stochastic Gradient Radial Basis Function Network Algorithms for Odor Sensing Systems

Learning behaviors of a radial basis function network (RBFN) using a singular value decomposition (SVD) and stochastic gradient (SG) algorithm, together named RBF‐SVD‐SG, for odor sensing systems are analyzed, and a fast training method is proposed. RBF input data is from a conducting polymer sensor array. It is revealed in this paper that the SG algorithm for the fine‐tuning of centers and widths still shows ill‐behaving learning results when a sufficiently small convergence coefficient is not used. Since the tuning of centers in RBFN plays a dominant role in the performance of RBFN odor sensing systems, our analysis is focused on the center‐gradient variance of the RBFN‐SVD‐SG algorithm. We found analytically that the steady‐state weight fluctuation and large values of a convergence coefficient can lead to an increase in variance of the center‐gradient estimate. Based on this analysis, we propose to use the least mean square algorithm instead of SVD in adjusting the weight for stable steady‐state weight behavior. Experimental results of the proposed algorithm have shown faster learning speed and better classification performance.     

Temperature Dependence of Microwave Properties of HTS Multipole Lowpass Filters Consisting of Microstrip Open-Stub Lines

Using high quality high-T_c superconducting (HTS) YBCO thin films, we designed and fabricated 3-pole, 5-pole, and 7-pole lowpass filters consisting of microstrip transmission lines and open-stub lines. We measured the microwave response of the filters in the temperature range of T=85 K to 27 K. At T = 30 K, the observed inband insertion loss was 0.14 dB and 0.02 dB for the 5-pole and 7-pole filters, respectively. The cut-off frequency was 4.7 GHz for the 5-pole filter and 7.9 GHz for the 7-pole filter. To the authors’ knowledge, the measured inband insertion losses are the best values reported so far for the open-stub line type HTS multipole lowpass filters. The skirt property of the 5-pole filter showed a large improvement over that of the 3-pole filter as predicted from the simulation. We found that, to obtain a stable performance, the HTS multipole lowpass filters should be operated at the temperatures between 60% and 70% of T_c.     

A Dual‐Mode 2.4‐GHz CMOS Transceiver for High‐Rate Bluetooth Systems

This paper reports on our development of a dual‐mode transceiver for a CMOS high‐rate Bluetooth system‐on‐chip solution. The transceiver includes most of the radio building blocks such as an active complex filter, a Gaussian frequency shift keying (GFSK) demodulator, a variable gain amplifier (VGA), a dc offset cancellation circuit, a quadrature local oscillator (LO) generator, and an RF front‐end. It is designed for both the normal‐rate Bluetooth with an instantaneous bit rate of 1 Mb/s and the high‐rate Bluetooth of up to 12 Mb/s. The receiver employs a dualconversion combined with a baseband dual‐path architecture for resolving many problems such as flicker noise, dc offset, and power consumption of the dual‐mode system. The transceiver requires none of the external image‐rejection and intermediate frequency (IF) channel filters by using an LO of 1.6 GHz and the fifth order on‐chip filters. The chip is fabricated on a 6.5‐mm² die using a standard 0.25‐μm CMOS technology. Experimental results show an in‐band image‐rejection ratio of 40 dB, an IIP3 of ?5 dBm, and a sensitivity of ?77 dBm for the Bluetooth mode when the losses from the external components are compensated. It consumes 42 mA in receive π/4‐diffrential quadrature phase‐shift keying (π/4‐DQPSK) mode of 8 Mb/s, 35 mA in receive GFSK mode of 1 Mb/s, and 32 mA in transmit mode from a 2.5‐V supply. These results indicate that the architecture and circuits are adaptable to the implementation of a low‐cost, multi‐mode, high‐speed wireless personal area network.     

Hydraulic-jump behavior of a thin film flowing down an inclined plane under an electrostatic field

The hydraulic-jump phenomenon of a thin fluid layer flowing down an inclined plane under an electrostatic field is explored by using a global bifurcation theory. First, the existence of hydraulic-hump wave has been found from heteroclinic trajectories of an associated ordinary differential equation. Then, the jump behavior has been characterized by introducing an intensity function on the variations of Reynolds number and surfave-wave speed. Finally, we have investigated the nonlinear stability of traveling shock waves triggered from a hydraulic jump by integrating the initial-value problem directly. At a given wave speed there exists a certain value of Reynolds number beyond which a time-dependent buckling of the free surface appears. Like the other wave motions such as periodic and pulse-like solitary waves, the hydraulic-jump waves are also found to become more unstable as the electrostatic field is getting stronger.     

Adaptive control approach of rapid thermal processing

This paper presents an adaptive control approach for achieving the control of the wafer temperature in a rapid thermal processing system (RTP). Numerous studies have addressed the temperature control problem in RTP and most researches on this problem require exact knowledge of the systems dynamics. However, it is difficult to acquire this exact knowledge. Thus, various approaches cannot guarantee the desired performance in practical application when there exist some modeling errors between the model and the actual system. In this paper, an adaptive control scheme is applied to RTP without exact information on the dynamics. The system dynamics are assumed to be an affine nonlinear form, and the unknown portion of the dynamics are estimated by a neural network referred to a piecewise linear approximation network (PLAN). The controller architecture is based on an adaptive feedback linearization scheme and augmented by sliding mode control. The performance of the proposed method is demonstrated by experimental results on an RTP system of Kornic Systems Corporation, Korea.     

Preparation of a new micro-porous poly(methyl methacrylate)-grafted polyethylene separator for high performance Li secondary battery

In this study, micro-porous poly(methyl methacrylate)-grafted polyethylene separators (PE-g-PMMA) were prepared by a radiation-induced graft polymerization of methyl methacrylate onto a conventional PE separator followed by a phase inversion. After the phase inversion, the micro-pores were generated in the grafted PMMA layer. The prepared micro-porous PE-g-PMMA separators showed an improved electrolyte uptake and ionic conductivity due to their improved affinity with a liquid electrolyte and the presence of pores in the grafted PMMA layer. The PE-g-PMMA separators exhibited a lower thermal shrinkage compared to the original PE separator. The PE-g-PMMA separators showed a better oxidation stability up to 5.0 V when compared to the original PE separator (4.5 V).