Showing papers by "Chung Yuan Christian University published in 2004"

Nanoscale Structural and Mechanical Characterization of a Natural Nanocomposite Material: The Shell of Red Abalone

Abstract: Nanoscale structural and mechanical characterization of the shell of a red abalone has been carried out. Cobble-like polygonal nanograins are basic building blocks that are used to construct individual aragonite platelets into a mother-of-pearl configuration known as nacre. The nanograin-structured aragonite platelets are not brittle in nature, but somewhat ductile. The deformability of the aragonite platelets together with the crack deflection, aragonite platelet slip, and organic adhesive interlayer contribute to the nacre's fracture toughness. Cracks formed in the outer prismatic layer of the shell do not show the crack diversion mechanism.

Effects of carbon nanosolids on the electro-optical properties of a twisted nematic liquid-crystal host

Abstract: We present results of the electro-optical effect in 90° twisted nematic cells of pristine and doped liquid crystals under an applied dc voltage. The doped cells were fabricated with a minute addition of either buckminsterfullerene C60 or multiwalled carbon nanotubes (CNTs). Investigated were the switching behaviors as well as the hystereses and time evolutions of both the optical transmittance and electrical capacitance of the display samples. It is shown that doping with nanotubes can effectively reduce the dc driving voltage and improve the switching behavior.

Using wavelet transform and fuzzy neural network for VPC detection from the holter ECG

Abstract: A novel method for detecting ventricular premature contraction (VPC) from the Holter system is proposed using wavelet transform (WT) and fuzzy neural network (FNN). The basic ideal and major advantage of this method is to reuse information that is used during QRS detection, a necessary step for most ECG classification algorithm, for VPC detection. To reduce the influence of different artifacts, the filter bank property of quadratic spline WT is explored. The QRS duration in scale three and the area under the QRS complex in scale four are selected as the characteristic features. It is found that the R wave amplitude has a marked influence on the computation of proposed characteristic features. Thus, it is necessary to normalize these features. This normalization process can reduce the effect of alternating R wave amplitude and achieve reliable VPC detection. After normalization and excluding the left bundle branch block beats, the accuracies for VPC classification using FNN is 99.79%. Features that are extracted using quadratic spline wavelet were used successfully by previous investigators for QRS detection. In this study, using the same wavelet, it is demonstrated that the proposed feature extraction method from different WT scales can effectively eliminate the influence of high and low-frequency noise and achieve reliable VPC classification. The two primary advantages of using same wavelet for QRS detection and VPC classification are less computation and less complexity during actual implementation.

A similarity-based robust clustering method

Abstract: This paper presents an alternating optimization clustering procedure called a similarity-based clustering method (SCM). It is an effective and robust approach to clustering on the basis of a total similarity objective function related to the approximate density shape estimation. We show that the data points in SCM can self-organize local optimal cluster number and volumes without using cluster validity functions or a variance-covariance matrix. The proposed clustering method is also robust to noise and outliers based on the influence function and gross error sensitivity analysis. Therefore, SCM exhibits three robust clustering characteristics: 1) robust to the initialization (cluster number and initial guesses), 2) robust to cluster volumes (ability to detect different volumes of clusters), and 3) robust to noise and outliers. Several numerical data sets and actual data are used in the SCM to show these good aspects. The computational complexity of SCM is also analyzed. Some experimental results of comparing the proposed SCM with the existing methods show the superiority of the SCM method.

Effect of pulse-burst electromagnetic field stimulation on osteoblast cell activities.

Abstract: Electric stimulation has been used successfully to treat a wide range of bone disorders. However, the mechanism by which the electric fields can influence the bone cells behavior remains poorly understood. The purpose of this research was to assess the possible mechanism of the stimulatory effect of pulsed electromagnetic field (PEMF) on bone cells. A PEMF with a frequency of 15 Hz (1 G [0.1 mT]; electric field strength 2 mV/cm) were applied to neonatal mouse calvarial bone cell cultures for 14 days. The temporal effects of PEMF on the osteoblasts were evaluated by the status of proliferation, differentiation, mineralization, and gene expression on the 3rd, 5th, 7th, and 14th days of culture. Our results demonstrated that PEMF stimulation significantly increased the osteoblasts' proliferation by 34.0, 11.5, and 13.3% over the control group after 3, 5, and 7 days' culture. Although the alkaline phosphatase (ALP) staining and the mineralization nodules formation did not change, the ALP activity of the bone cells decreased significantly after PEMF stimulation. Under the PEMF stimulation, there was no effect on the extracellular matrix synthesis, while the osteoprotegerin (OPG) mRNA expression was up regulated and the receptor activator of NF-kappaB ligand (RANKL) mRNA expression were down regulated, compared to the control. In conclusion, the treatment by PEMF of osteoblasts may accelerate cellular proliferation, but did not affect the cellular differentiation. The effect of PEMF stimulation on the bone tissue formation was most likely associated with the increase in the number of cells, but not with the enhancement of the osteoblasts' differentiation.

Key quality performance evaluation using fuzzy ahp

Abstract: This research proposes an evaluation model that integrates triangular fuzzy numbers and the analytical hierarchy process to develop a fuzzy multiple-attribute decision-making(FMADM) model for key quality-performance evaluation. Using the proposed model, decision-makers can determine, in advance, critical quality elements that might significantly affect quality performance. A practical example of an electronic product has been used to illustrate the theoretical qualitative proposed evaluation model. Results demonstrate that decision-makers can use the flexibility of the proposed model by adjusting the confidence coefficient to express their degree of understangidng with respect to the importance of each component. Moreover, the result of FMADM analysis is a significant contribution to quality improvement.

Preparation and properties of novel benzoxazine and polybenzoxazine with maleimide groups

Abstract: A benzoxazine compound with a maleimide group, 3-phenyl-3,4-dihydro-2H-6-(N-maleimido)-1,3-benzoxazine (HPM-Ba), was prepared from N-(4-hydroxyphenyl)maleimide, formaldehyde, and aniline. The chemical structure of HBM-Ba was identified by FT-IR, 1H-NMR, and elemental analysis. HPM-Ba showed a melting point of 52–55 °C and good solubility in common organic solvents. HPM-Ba showed a two-stage process of thermal polymerization. The first stage arose from the polymerization of maleimide groups, and the second one was the ring-opening reaction of benzoxazine groups. Fusible polymaleimides with a Tg of around 100 °C could be obtained by thermally polymerizing HPM-Ba at 130 °C. Further polymerizing the polymaleimides at 240 °C resulted in a completely cured resin showing a Tg at 204 °C. Good thermal stability and self-extinguishing behavior was observed with the cured polybenzoxazine resins. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5954–5963, 2004

An integrated model of TQM and GE-Six-Sigma

Abstract: TQM has enjoyed great popularity in industries of all types since its development in the mid-1980s. However, in recent years, interest in TQM has declined. In contrast, Six-Sigma, especially in its form implemented by General Electric (GE-6σ), has become a popular management tool in the world. As a result, some researchers and practitioners assert that firms should implement Six-Sigma in preference to TQM. This paper analyses the contents and practices of TQM and Six-Sigma, and compares them against twelve dimensions. It is concluded that TQM cannot be replaced by Six-Sigma. However, TQM cannot obtain the radical results achieved by Six-Sigma. It is suggested that the implementation of Six-Sigma can make up for this deficiency in TQM. Although the manipulation and management practices of TQM and GE-6σ are somewhat different, there is congruence between their quality concepts, leadership, and culture. In addition, TQM and GE-6σ share the same goals of pursuing customer satisfaction and business profits, and the integration of TQM and GE-6σ should therefore have synergistic effects. The present paper utilises customer loyalty and business performance as the strategic goal of an integrated model of the two programmes. The proposed model discusses management principles, implementation practices, and cultural changes implied by integration. This integrated model is of significance for practitioners and academics alike.

Comparative studies of the properties of poly(methyl methacrylate)–clay nanocomposite materials prepared by in situ emulsion polymerization and solution dispersion

Abstract: A series of polymer–clay nanocomposite (PCN) materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic montmorillonite (MMT) clay platelets were prepared successfully by the effective dispersion of nanolayers of the MMT clay in the PMMA framework through both in situ emulsion polymerization and solution dispersion. The as-prepared PCN materials obtained with both approaches were subsequently characterized with wide-angle powder X-ray diffraction and transmission electron microscopy. For a comparison of the anticorrosion performance, a PCN material (e.g., 3 wt % clay loading) prepared by in situ emulsion polymerization, showing better dispersion of the clay platelets in the polymer matrix, exhibited better corrosion protection in the form of a coating on a cold-rolled steel coupon than that prepared by solution dispersion, which showed a poor dispersion of the clay nanolayers according to a series of electrochemical corrosion measurements. Comparative studies of the optical clarity, molecular barrier properties, and thermal stability of samples prepared in both ways, as membranes and fine powders, were also performed with ultraviolet–visible transmission spectroscopy, molecular permeability analysis, thermogravimetric analysis, and differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1936–1946, 2004

Video stabilization for a camcorder mounted on a moving vehicle

Abstract: Vision systems play an important role in many intelligent transportation systems (ITS) applications, such as traffic monitoring, traffic law reinforcement, driver assistance, and automatic vehicle guidance. These systems installed in either outdoor environments or vehicles have often suffered from image instability. In this paper, a video stabilization technique for a camcorder mounted on a moving vehicle is presented. The proposed approach takes full advantage of the a priori information of traffic images, significantly reducing the computational and time complexities. There are four major steps involved in the proposed approach: global feature extraction, camcorder motion estimation, motion taxonomy, and image compensation. We begin with extracting the global features of lane lines and the road vanishing point from the input image. The extracted features are then combined with those detected in previous images to compute the camcorder motion corresponding to the current input image. The computed motion consists of both expected and unexpected components. They are discriminated and the expected motion component is further smoothed. The resulting motion is next integrated with a predicted motion, which is extrapolated from the previous desired camcorder motions, leading to the desired camcorder motion associated with the input image under consideration. The current input image is finally stabilized based on the computed desired camcorder motion using an image transformation technique. A series of experiments with both real and synthetic data have been conducted. The experimental results have revealed the effectiveness of the proposed technique.

Micro-power low-offset instrumentation amplifier IC design for biomedical system applications

Abstract: This work presents a micro-power low-offset CMOS instrumentation amplifier integrated circuit with a large operating range for biomedical system applications. The equivalent input offset voltage is improved using a new circuit technique of offset cancellation that involves a two-phase clocking scheme with a frequency of 20 kHz. Channel charge injection is cancelled by the symmetrical circuit topology. With the wide-swing cascode bias circuit design, this amplifier realizes a very high power-supply rejection ratio (PSRR), and can be operated at single supply voltage in the range between 2.5-7.5 V. It was fabricated using 0.5-/spl mu/m double-poly double-metal n-well CMOS technology, and occupies a die area of 0.2 mm/sup 2/. This amplifier achieves a 160-/spl mu/V typical input offset voltage, 0.05% gain linearity, greater than 102-dB PSRR, an input-referred rms noise voltage of 45 /spl mu/V, and a current consumption of 61 /spl mu/A at a low supply voltage of 2.5 V. Experimental results indicate that the proposed amplifier can process the input electrocardiogram signal of a patient monitoring system and other portable biomedical devices.

Anti-apoptotic effects of curcumin on photosensitized human epidermal carcinoma A431 cells

Abstract: Photodynamic treatment (PDT) can elicit a diverse range of cellular responses, including apoptotic cell death. Previously, we showed that PDT stimulates caspase-3 activation and subsequent cleavage and activation of p21-activated kinase 2 (PAK2) in human epidermal carcinoma A431 cells. Curcumin, the yellow pigment of Curcuma longa, is known to have anti-oxidant and anti-inflammatory properties. In the present study, using Rose Bengal (RB) as the photosensitizer, we investigated the effect of curcumin on PDT-induced apoptotic events in human epidermal carcinoma A431 cells. We report that curcumin prevented PDT-induced JNK activation, mitochondrial release of cytochrome c, caspase-3 activation, and cleavage of PAK2. Using the cell permeable dye DCF-DA as an indicator of reactive oxygen species (ROS) generation, we found that both curcumin and ROS scavengers (i.e., l-histidine, a-tocopherol, mannitol) abolished PDT-stimulated intracellular oxidative stress. Moreover, all these PDT-induced apoptotic changes in cells could be blocked by singlet oxygen scavengers (i.e., l-histidine, a-tocopherol), but were not affected by the hydroxyl radical scavenger mannitol. In addition, we found that SP600125, a JNK-specific inhibitor, reduced PDT-induced JNK activation as well as caspase-3 activation, indicating that JNK activity is required for PDT-induced caspase activation. Collectively, these results demonstrate that singlet oxygen triggers JNK activation, cytochrome c release, caspase activation and subsequent apoptotic biochemical changes during PDT and show that curcumin is a potent inhibitor for this process.

ISFET interface circuit embedded with noise rejection capability

Abstract: A new constant-current voltage driver forms a bridge-type floating drain-source follower configuration applicable to the determination of H+ ion concentration. The proposed circuit maintains the ion-selective field effect transistor (ISFET) in an accurate constant drain-source voltage and current situation with good noise rejection capability. Simulation results show accurate response for ISFET applications. The presented electronic circuit can be integrated with a ISFET-based microsystem by standard CMOS technology.

Sesamin induces nitric oxide and decreases endothelin-1 production in HUVECs: possible implications for its antihypertensive effect

Abstract: ObjectiveSesamin has been proved to be antihypertensive. Nitric oxide (NO) is the most important vascular relaxing factor that is regulated in endothelium. Endothelin-1 (ET-1) is characterized as a potent vasoconstrictor and is also regulated in endothelium. Alterations in the endothelial production

Preparation and properties of polyimide–clay nanocomposite materials for anticorrosion application

Abstract: A series of polymer–clay nanocomposite (PCN) materials that consist of organosoluble polyimide and layered montmorillonite clay were prepared by the solution dispersion technique. The organosoluble polyimide containing non-coplanar moiety in diamine monomer and flexible bridging linkages in dianhydride monomer was synthesized by chemical imidization. The as-synthesized PCN materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. The organosoluble polyimide showed better corrosion resistance compared to polyaniline, poly(o-ethoxyaniline) and poly(methyl methacrylate) by using a series of standard electrochemical corrosion measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Polyimide–clay nanocomposite materials incorporated with low loading of clay were found to further improve corrosion inhibition over pure polyimide. Effects of the material composition on the O2/H2O molecular permeability, optical clarity, and thermal properties of polyimide–clay nanocomposite materials were studied by molecular permeability analysis, UV–visible transmission spectra, thermogravimetric analysis, and differential scanning calorimetry, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3573–3582, 2004

Similarity measures between type-2 fuzzy sets

Abstract: In this paper, we give similarity measures between type-2 fuzzy sets and provide the axiom definition and properties of these measures. For practical use, we show how to compute the similarities between Gaussian type-2 fuzzy sets. Yang and Shih's [22] algorithm, a clustering method based on fuzzy relations by beginning with a similarity matrix, is applied to these Gaussian type-2 fuzzy sets by beginning with these similarities. The clustering results are reasonable consisting of a hierarchical tree according to different levels.