Showing papers by "National Chung Hsing University published in 2006"

Abundance-based similarity indices and their estimation when there are unseen species in samples.

Abstract: A wide variety of similarity indices for comparing two assemblages based on species incidence (i.e., presence/absence) data have been proposed in the literature. These indices are generally based on three simple incidence counts: the number of species shared by two assemblages and the number of species unique to each of them. We provide a new probabilistic derivation for any incidence-based index that is symmetric (i.e., the index is not affected by the identity ordering of the two assemblages) and homogeneous (i.e., the index is unchanged if all counts are multiplied by a constant). The probabilistic approach is further extended to formulate abundance-based indices. Thus any symmetric and homogeneous incidence index can be easily modified to an abundance-type version. Applying the Laplace approximation formulas, we propose estimators that adjust for the effect of unseen shared species on our abundance-based indices. Simulation results show that the adjusted estimators significantly reduce the biases of the corresponding unadjusted ones when a substantial fraction of species is missing from samples. Data on successional vegetation in six tropical forests are used for illustration. Advantages and disadvantages of some commonly applied indices are briefly discussed.

A New Growing Method for Simplex-Based Endmember Extraction Algorithm

Abstract: A new growing method for simplex-based endmember extraction algorithms (EEAs), called simplex growing algorithm (SGA), is presented in this paper. It is a sequential algorithm to find a simplex with the maximum volume every time a new vertex is added. In order to terminate this algorithm a recently developed concept, virtual dimensionality (VD), is implemented as a stopping rule to determine the number of vertices required for the algorithm to generate. The SGA improves one commonly used EEA, the N-finder algorithm (N-FINDR) developed by Winter, by including a process of growing simplexes one vertex at a time until it reaches a desired number of vertices estimated by the VD, which results in a tremendous reduction of computational complexity. Additionally, it also judiciously selects an appropriate initial vector to avoid a dilemma caused by the use of random vectors as its initial condition in the N-FINDR where the N-FINDR generally produces different sets of final endmembers if different sets of randomly generated initial endmembers are used. In order to demonstrate the performance of the proposed SGA, the N-FINDR and two other EEAs, pixel purity index, and vertex component analysis are used for comparison

Expression of artificial microRNAs in transgenic Arabidopsis thaliana confers virus resistance

Abstract: Plant microRNAs (miRNAs) regulate the abundance of target mRNAs by guiding their cleavage at the sequence complementary region. We have modified an Arabidopsis thaliana miR159 precursor to express artificial miRNAs (amiRNAs) targeting viral mRNA sequences encoding two gene silencing suppressors, P69 of turnip yellow mosaic virus (TYMV) and HC-Pro of turnip mosaic virus (TuMV). Production of these amiRNAs requires A. thaliana DICER-like protein 1. Transgenic A. thaliana plants expressing amiR-P69159 and amiR-HC-Pro159 are specifically resistant to TYMV and TuMV, respectively. Expression of amiR-TuCP159 targeting TuMV coat protein sequences also confers specific TuMV resistance. However, transgenic plants that express both amiR-P69159 and amiR-HC-Pro159 from a dimeric pre-amiR-P69159/amiR-HC-Pro159 transgene are resistant to both viruses. The virus resistance trait is displayed at the cell level and is hereditable. More important, the resistance trait is maintained at 15 °C, a temperature that compromises small interfering RNA–mediated gene silencing. The amiRNA-mediated approach should have broad applicability for engineering multiple virus resistance in crop plants.

Age-stage, two-sex life tables of Aphidius gifuensis (Ashmead) (Hymenoptera : Braconidae) and its host Myzus persicae (Sulzer) (Homoptera : Aphididae) with mathematical proof of the relationship between female fecundity and the net reproductive rate

Abstract: Life history data for Aphidius gifuensis (Ashmead) and Myzus persicae (Sulzer) were collected in the laboratory. To consider both sexes and variable developmental rates among individ- uals, the raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase (r) for A. gifuensis is 0.264 d 1 . The mean parasitism rate is 92.3 aphids per female. The intrinsic rate of increase for M. persicae is 0.252 d 1 . For applying the female age-speciÞc life table to a female population, we prove that the relationship between the mean female fecundity (F) and the net reproductive rate (R0 )i sR0saF, where sa is the preadult survival rate. When the female age-speciÞc life table is applied to two-sex populations, the relationship between F and R0 is R0 sawF, where sa is the preadult survival rate of females, and w is the female proportion in offspring. This is valid when w is a constant for the age-speciÞc fecundity (mx) of all ages. Because sexing preadult individuals is difÞcult, and obtaining a constant sex ratio in offspring is uncertain, determining preadult mortality of the individual sexes may be problematical. As a result, calculations of the age-speciÞc survival rate (lx) and fecundity and population parameters may be adversely affected. Moreover, if lx and mx are constructed based on adult age, they may also cause errors in population parameters. Because the application of female age-speciÞc life table to stage-structured bisexual population results in inac- curacies, we recommend that the age-stage, two-sex life table should be used in insect demographic studies.

A comparative study on shadow compensation of color aerial images in invariant color models

Abstract: In urban color aerial images, shadows cast by cultural features may cause false color tone, loss of feature information, shape distortion of objects, and failure of conjugate image matching within the shadow area. This paper presents an automatic property-based approach for the detection and compensation of shadow regions with shape information preserved in complex urban color aerial images for solving problems caused by cast shadows in digital image mapping. The technique is applied in several invariant color spaces that decouple luminance and chromaticity, including HSI, HSV, HCV, YIQ, and YC/sub b/C/sub r/ models. Experimental results from de-shadowing color aerial images of a complex building and a highway segment in these color models are evaluated in terms of visual comparisons and shadow detection accuracy assessments. The results show the effectiveness of the proposed approach in revealing details under shadows and the suitability of these color models in de-shadowing urban color aerial images.

Security Enhancement on a New Authentication Scheme With Anonymity for Wireless Environments

Abstract: In a paper recently published in the IEEE Transactions on Consumer Electronics, Zhu and Ma proposed a new authentication scheme with anonymity for wireless environments. However, this paper shows that Zhu and Ma's scheme has some security weaknesses. Therefore, in this paper, a slight modification to their scheme is proposed to improve their shortcomings. As a result, the scheme proposed in this paper can enhance the security of Zhu and Ma's scheme. Finally, the performance of this scheme is analyzed. Compared with the Zhu-Ma scheme, this scheme is also simple and efficient

Fermentative hydrogen production and bacterial community structure in high-rate anaerobic bioreactors containing silicone-immobilized and self-flocculated sludge.

Abstract: A novel continuously stirred anaerobic bioreactor (CSABR) seeded with silicone-immobilized sludge was developed for high-rate fermentative H2 production using sucrose as the limiting substrate. The CSABR system was operated at a hydraulic retention time (HRT) of 0.5-6 h and an influent sucrose concentration of 10-40 g COD/L. With a high feeding sucrose concentration (i.e., 30-40 g COD/L) and a short HRT (0.5 h), the CSABR reactor produced H2 more efficiently with the highest volumetric rate (VH2) of 15 L/h/L (i.e., 14.7 mol/d/L) and an optimal yield of ca. 3.5 mol H2/mol sucrose. The maximum VH2 value obtained from this work is much higher than any other VH2 values ever documented. Formation of self-flocculated granular sludge occurred during operation at a short HRT. The granule formation is thought to play a pivotal role in the dramatic enhancement of H2 production rate, because it led to more efficient biomass retention. A high biomass concentration of up to 35.4 g VSS/L was achieved even though the reactor was operated at an extremely low HRT (i.e., 0.5 h). In addition to gaining high biomass concentrations, formation of granular sludge also triggered a transition in bacterial community structure, resulting in a nearly twofold increase in the specific H2 production rate. According to denatured-gradient-gel-electrophoresis analysis, operations at a progressively decreasing HRT resulted in a decrease in bacterial population diversity. The culture with the best H2 production performance (at HRT = 0.5 h and sucrose concentration = 30 g COD/L) was eventually dominated by a presumably excellent H2-producing bacterial species identified as Clostridium pasteurianum.

Removal of zinc(ii) from aqueous solution by purified carbon nanotubes: kinetics and equilibrium studies

Abstract: Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were purified by sodium hypochlorite solutions and were employed as sorbents to study the kinetics and equilibrium of Zn2+ sorption from aqueous solution. The amount of Zn2+ sorbed onto CNTs increased with a rise in temperature. Using the same conditions, the Zn2+ sorption capacity of CNTs was much greater than that of commercially available powdered activated carbon, reflecting that SWCNTs and MWCNTs are effective sorbents. The thermodynamic analysis revealed that the sorption of Zn2+ onto CNTs is endothermic and spontaneous. The sorption/desorption study showed that the Zn2+ ions could be easily removed from the surface site of SWCNTs and MWCNTs by a 0.1 mol/L nitric acid solution and the sorption capacity was maintained after 10 cycles of the sorption/desorption process. This suggests that both CNTs can be reused through many cycles of water treatment and regeneration.

Ring-Opening Polymerization of Lactides Initiated by Zinc Alkoxides Derived from NNO-Tridentate Ligands

Abstract: A new series of dinuclear zinc complexes of the types [LZnEt]2 and [LZn(μ-OBn)]2 (where L = NNO-tridentate Schiff base ligand) have been prepared. The activities of zinc alkoxides, [LZn(μ-OBn)]2, toward the ring-opening polymerization of l-lactide have been investigated. Experimental results indicate that the reactivity of [LZn(μ-OBn)]2 was dramatically affected by both the electronic and steric effect of the substituents on the Schiff base. The polymerization kinetics using [L1Zn(μ-OBn)]2 (2a) as an initiator were also studied, and the experimental results reveal that the rate of reaction is first-order, which depends on both [LA] and [L1Zn(μ-OBn)]2. Furthermore, the heterotactic PLA with Pr up to 91% can be achieved by initiating of [L5Zn(μ-OBn)]2 in CH2Cl2 at −55 °C.

Preparation and characterization of AlCrTaTiZr multi-element nitride coatings

Abstract: Multi-element nitride films of AlCrTaTiZr high-entropy alloy have been prepared in this study by reactive radio-frequency magnetron sputtering The influences of nitrogen flow ratio on the chemical composition, microstructure and mechanical properties of the deposited nitride films have been investigated The AlCrTaTiZr alloy film exhibited an amorphous structure, while a simple face-center-cubic solid-solution structure was observed in the nitride films prepared under different nitrogen flow ratios The multi-element AlCrTaTiZr nitride films exhibited much improved mechanical properties as compared with conventional nitride hard coatings of transition metals

Removal of nickel(II) from aqueous solution by carbon nanotubes

Abstract: Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were oxidized by NaClO solutions and were employed as sorbents to study sorption characteristics of nickel(II) from aqueous solution. The surface properties of CNTs such as functional groups, total acidic sites and negatively charged carbons were greatly improved after oxidation, which made CNTs become more hydrophilic and resulted in sorption of more Ni2+. The amount of Ni2+ sorbed onto oxidized CNTs increased with a rise in agitation speed, initial Ni2+ concentration and solution pH in the range 1–8, but decreased with a rise in CNT mass and solution ionic strength. The sorption mechanisms are complicated and appear attributable to electrostatic forces and chemical interactions between the Ni2+ and the surface functional groups of the CNTs. The oxidized SWCNTs and MWCNTs have shorter equilibrium time and better Ni2+ sorption performance than the oxidized granular activated carbon, suggesting that both NaClO oxidized CNTs are efficient Ni2+ sorbents and that they possess good potential applications in water treatment. Copyright © 2006 Society of Chemical Industry

Antioxidant activity and bioactive compounds of tea seed (Camellia oleifera Abel.) oil.

Abstract: The oil of tea seed (Camellia oleifera Abel.) is used extensively in China as cooking oil. The objectives of this study were to investigate the antioxidant activity of tea seed oil and its active compounds. Of the five solvent extracts, methanol extract of tea seed oil exhibited the highest yield and the strongest antioxidant activity as determined by DPPH scavenging activity and Trolox equivalent antioxidant capacity (TEAC). Two peaks separated from the methanol extract by HPLC contributed the most significant antioxidant activity. These two peaks were further identified as sesamin and a novel compound: 2,5-bis-benzo[1,3]dioxol-5-yl-tetrahydro-furo [3,4-d][1,3]dioxine (named compound B) by UV absorption and characterized by MS, IR, 1H NMR, and 13C NMR techniques. Sesamin and compound B decreased H2O2-mediated formation of reactive oxygen species in red blood cells (RBCs), inhibited RBCs hemolysis induced by AAPH, and increased the lag time of conjugated dienes formation in human low-density lipoprotein. The results indicate that both compounds isolated from tea seed oil exhibit remarkable antioxidant activity. Apart from the traditional pharmacological effects of Camellia oleifera, the oil of tea seed may also act as a prophylactic agent to prevent free radical related diseases.

Reversible Watermarking: Current Status and Key Issues

Abstract: Over the past few years a number of research papers about reversible watermarks has been produced. Reversible watermarking is a novel category of watermarking schemes. It not only can strengthen the ownership of the original media but also can completely recover the original media from the watermarked media. This feature is suitable for some important media, such as medical and military images, because these kinds of media do not allow any losses. The aim of this paper is to define the purpose of reversible watermarking, reflecting recent progress, and provide some research issues for the future.

Induction of Hepatic Antioxidant Enzymes by Phenolic Acids in Rats Is Accompanied by Increased Levels of Multidrug Resistance–Associated Protein 3 mRNA Expression

Abstract: Phenolic acids are widespread in plant foods; they contain important biological and pharmacological properties, some of which were shown to be effective in preventing cancer. We investigated the modulatory effects of phenolic acids on an antioxidant system in male Sprague-Dawley rats. Rats were orally administrated gentisic acid (GEA), gallic acid (GA), ferulic acid (FA), and p-coumaric acid (p-CA) at a dosage of 100 mg/kg body weight for 14 consecutive days. At this dose, the activities of hepatic superoxide dismutase (SOD), glutathione peroxidase (GPx), and catalase were greater after administration of all 4 phenolic acids compared with the control group (P < 0.05). The activities of these enzymes in the small intestine of rats were also significantly greater after GA and p-CA treatment compared with controls. The changes in hepatic CuZnSOD, GPx, and catalase mRNA levels induced by phenolic acids were similar to those noted in the enzyme activities. Oxidized glutathione levels were lower (P < 0.05) in the liver of all phenolic acid-supplemented rats, whereas reduced glutathione was markedly higher than in control rats, especially after administration of GA and p-CA. The liver homogenates obtained from rats that had been administered phenolic acids had higher oxygen radical absorbance capacity than those obtained from control rats. Immunoblot analysis revealed an increased total level of Nrf2, a transcription factor governing the antioxidant response element in phenolic acid-supplemented rats. Phenolic acid-mediated antioxidant enzyme expression was accompanied by upregulation of multidrug resistance-associated protein Mrp3. These experiments show that modulation of phase II antioxidant enzymes and oxidative status in the liver by phenolic acids may play an important role in the protection against adverse effects related to mutagenesis and oxidative damage.

Visible-light-induced bactericidal activity of a nitrogen-doped titanium photocatalyst against human pathogens.

Abstract: The antibacterial activity of photocatalytic titanium dioxide (TiO2) substrates is induced primarily by UV light irradiation. Recently, nitrogen- and carbon-doped TiO2 substrates were shown to exhibit photocatalytic activities under visible-light illumination. Their antibacterial activity, however, remains to be quantified. In this study, we demonstrated that nitrogen-doped TiO2 substrates have superior visible-light-induced bactericidal activity against Escherichia coli compared to pure TiO2 and carbon-doped TiO2 substrates. We also found that protein- and light-absorbing contaminants partially reduce the bactericidal activity of nitrogen-doped TiO2 substrates due to their light-shielding effects. In the pathogen-killing experiment, a significantly higher proportion of all tested pathogens, including Shigella flexneri, Listeria monocytogenes, Vibrio parahaemolyticus, Staphylococcus aureus, Streptococcus pyogenes, and Acinetobacter baumannii, were killed by visible-light-illuminated nitrogen-doped TiO2 substrates than by pure TiO2 substrates. These findings suggest that nitrogen-doped TiO2 has potential application in the development of alternative disinfectants for environmental and medical usages.

Inhibition of lung cancer cell growth by quercetin glucuronides via g2/m arrest and induction of apoptosis

Abstract: Lung cancer is the leading cause of cancer death in many developed countries, including Taiwan. Quercetin, a widely distributed bioflavonoid, is well known to induce growth inhibition in a variety of human cancer cells. Quercetin glucuronides are the main circulating metabolites after dietary supplements with quercetin in humans. However, there is little information available as to how quercetin glucuronides affect human cancer cells. We investigated the effects of quercetin glucuronides in a human lung cancer cell line NCI-H209. We checked the cell viability, cell cycle checkpoint proteins, pro- and antiapoptotic proteins, caspase-3 activity, and gene expression by flow cytometry and Western blot. The viability of cells decreased in a dose- and time-dependent manner. Cell cycle analysis revealed a significant increase of the proportion of cells in G2/M phase and subG0/G1 phase (corresponding to apoptotic cells). Moreover, quercetin glucuronides increased the expressions of cyclin B, Cdc25c-ser-216-p, and Wee1 proteins, indicating the G2/M arrest. We also demonstrated a concurrent decrease of the mitochondrial membrane potential, release of cytochrome c, up-regulation of Bax, down-regulation of Bcl-2, and activation of caspase-3, and subsequently, cleavage of poly(ADP-ribose) polymerase. In addition, quercetin glucuronide-induced apoptosis was totally blocked by the broad-spectrum caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp fluoromethylketone. Taken together, we demonstrated that quercetin glucuronides inhibited proliferation through G2/M arrest of the cell cycle and induced apoptosis via caspase-3 cascade in the human lung cancer cell line NCI-H209. Delineation of the biological effects of specific major quercetin metabolites on chemotherapeutic potential or chemoprevention of human cancers warrants further investigation.