Showing papers by "National Chung Hsing University published in 2004"

Nanostructured High-Entropy Alloys with Multiple Principal Elements: Novel Alloy Design Concepts and Outcomes

Abstract: A new approach for the design of alloys is presented in this study. These high-entropy alloys with multi-principal elements were synthesized using well-developed processing technologies. Preliminary results demonstrate examples of the alloys with simple crystal structures, nanostructures, and promising mechanical properties. This approach may be opening a new era in materials science and engineering.

A hybrid of genetic algorithm and particle swarm optimization for recurrent network design

Abstract: An evolutionary recurrent network which automates the design of recurrent neural/fuzzy networks using a new evolutionary learning algorithm is proposed in this paper. This new evolutionary learning algorithm is based on a hybrid of genetic algorithm (GA) and particle swarm optimization (PSO), and is thus called HGAPSO. In HGAPSO, individuals in a new generation are created, not only by crossover and mutation operation as in GA, but also by PSO. The concept of elite strategy is adopted in HGAPSO, where the upper-half of the best-performing individuals in a population are regarded as elites. However, instead of being reproduced directly to the next generation, these elites are first enhanced. The group constituted by the elites is regarded as a swarm, and each elite corresponds to a particle within it. In this regard, the elites are enhanced by PSO, an operation which mimics the maturing phenomenon in nature. These enhanced elites constitute half of the population in the new generation, whereas the other half is generated by performing crossover and mutation operation on these enhanced elites. HGAPSO is applied to recurrent neural/fuzzy network design as follows. For recurrent neural network, a fully connected recurrent neural network is designed and applied to a temporal sequence production problem. For recurrent fuzzy network design, a Takagi-Sugeno-Kang-type recurrent fuzzy network is designed and applied to dynamic plant control. The performance of HGAPSO is compared to both GA and PSO in these recurrent networks design problems, demonstrating its superiority.

Formation of simple crystal structures in Cu-Co-Ni-Cr-Al-Fe-Ti-V alloys with multiprincipal metallic elements

Abstract: Crystalline solid solutions are typically formed in conventional alloys based on one or two host elements. Here, in this research, four alloys containing multiprincipal metallic elements (≥5 elements) were prepared by casting, splat quenching, and sputtering. Their microstructures and crystal structures were investigated. It was interestingly found that solid solutions with simple fcc or bcc crystal structure were also practically formed in these alloys with multiprincipal elements. All different atoms are regarded as solutes and expected to randomly distribute in the crystal lattices without any matrix element defined.

Yield Variability as Influenced by Climate: A Statistical Investigation

Abstract: One of the issues with respect to climate change involves its influence on the distribution of future crop yields. Many studies have been done regarding the effect on the mean of such distributions but few have addressed the effect on variance. Furthermore, those that have been done generally report the variance from crop simulators, not from observations. This paper examines the potential effects of climate change on crop yield variance in the context of current observed yields and then extrapolates to the effects under projected climate change. In particular, maximum likelihood panel data estimates of the impacts of climate on year-to-year yield variability are constructed for the major U.S. agricultural crops. The panel data technique used embodies a variance estimate developed along the lines of the stochastic production function approach suggested by Just and Pope. The estimation results indicate that changes in climate modify crop yield levels and variances in a crop-specific fashion. For sorghum, rainfall and temperature increases are found to increase yield level and variability. On the other hand, precipitation and temperature are individually found to have opposite effects on corn yield levels and variability.

Price and Volatility Spillovers between Stock Prices and Exchange Rates: Empirical Evidence from the G-7 Countries

Abstract: This paper explores the nature of the mean and volatility transmission mechanism between stock and foreign exchange markets for the G-7 countries. Empirical evidence supports the asymmetric volatility spillover effect and shows that movements of stock prices will affect future exchange rate movements, but changes in exchange rates have less direct impact on future changes of stock prices. The implication is particularly important to international portfolio managers when devising hedging and diversification strategies for their portfolios.

Mutation of a Nitrate Transporter, AtNRT1:4, Results in a Reduced Petiole Nitrate Content and Altered Leaf Development

Abstract: ;Unlike nitrate uptake of plant roots, less is known at the molecular level about how nitrate is distributed in various plant tissues. In the present study, characterization of the nitrate transporter, AtNRT1:4, revealed a special role of petiole in nitrate homeostasis. Electrophysiological studies using Xenopus oocytes showed that AtNRT1:4 was a lowaffinity nitrate transporter. Whole-mount in situ hybridization and RT–PCR demonstrated that AtNRT1:4 was expressed in the leaf petiole. In the wild type, the leaf petiole had low nitrate reductase activity, but a high nitrate content, indicating that it is the storage site for nitrate, whereas, in the atnrt1:4 mutant, the petiole nitrate content was reduced to 50–64% of the wild-type level. Moreover, atnrt1:4 mutant leaves were wider than wild-type leaves. This study revealed a critical role of AtNRT1:4 in regulating leaf nitrate homeostasis, and the deficiency of AtNRT1: 4 can alter leaf development.

Foreign direct investment and local linkages

Abstract: This paper analyses the pattern of local linkages in foreign direct investment (FDI), treating such local linkages as an investment in local relationships Using Taiwanese manufacturing firms investing abroad as the sample for our case study, we find that the local linkage intensity of a foreign subsidiary differs by FDI location, entry mode, firm size and the nature of the production network in which an investor is embedded More local linkages will be pursued by an investor if it is in search of distinctive and inimitable resources as opposed to homogeneous and reproducible resources Investment in local linkages always begins with the linkage that carries the lowest risk to the original business network For manufacturing firms, the sequence of such linkages is: workers, components and parts, subcontracting and, finally, sources of R&D

Evaluation of Chitosan-alginate-hyaluronate Complexes Modified by an RGD-containing Protein as Tissue-engineering Scaffolds for Cartilage Regeneration

Abstract: In this study, a series of natural biodegradable materials in the form of chitosan (C)-alginate (A)-hyaluronate (H) complexes are evaluated as tissue-engineering scaffolds. The weight ratio of C/A is 1 : 1 or 1 : 2. Sodium hyaluronate is mixed in 2%. The complexes can be cast into films or fabricated as scaffolds. Their surface can be further modified by an Arg-Gly-Asp (RGD)-containing protein, a cellulose-binding domain-RGD (R). Cytocompatibility tests of the films are conducted using immortalized rat chondrocyte (IRC) as well as primary articular chondrocytes harvested from rabbits. The neocartilage formation in cell-seeded scaffolds is examined in vitro as well as in rabbits, where the scaffolds are implanted into the defect-containing joints. The results from cytocompatibility tests demonstrate that R enhances cell attachment and proliferation on C-A and C-A-H complex films. Complex C1A1HR (C : A = 1 : 1 with H and R) has better performance than the other formulation. Cells retain their spherical morphology on all C-A and C-A-H complexes. The in vitro evaluation of the seeded scaffolds indicates that the C1A1HR complex is the most appropriate for 3-D culture, manifested by the better cell growth as well as higher glycosaminoglycan and collagen contents. When the chondrocyte scaffolds are implanted into rabbit knee cartilage defects, partial repair is observed after 1 month in C1A1HR as well as in C1A1 (C : A = 1 : 1 without H and R) scaffolds. The defects are completely repaired in 6 months when C1A1HR constructs are implanted. It is concluded that C1A1HR is a potential tissue-engineering scaffold for cartilage regeneration.

High fill-factor microlens array mold insert fabrication using a thermal reflow process

Abstract: An extreme high fill-factor microlens array mold insert in photoresist fabrication using a thermal reflow process is presented. The experimental results proved that a square microlens array could be produced without a peripheral gap. A square microlens array with an extreme high fill-factor (almost 100%) was successfully fabricated. In this experiment, square photoresist columns were formed on a silicon substrate using a lithographic process. The square pattern was laid out in an ortho-square on a polyethylene terephthalate (PET) based mask. Precise temperature and time control was used during the thermal reflow process. The square microlens array was formed from the uniformly flowing melted photoresist. The photoresist column surface transforms into a spherical profile due to the surface tension effect. The error was within ±8% between the fabricated microlens characteristics and the theoretical model used to predict the photoresist column thickness and actual thickness. This model is feasible for fabricating various sized high fill-factor square microlens arrays.

Expression and distribution of Na, K-ATPase in gill and kidney of the spotted green pufferfish, Tetraodon nigroviridis, in response to salinity challenge

Abstract: Freshwater (FW) spotted green pufferfish (Tetraodon nigroviridis) were transferred directly from a local aquarium to fresh water (FW; 0x), brackish water (BW; 15x), and seawater (SW; 35x) conditions in the laboratory and reared for at least two weeks. No mortality was found. To investigate the efficient mechanisms of osmoregulation in the euryhaline teleost, distribution and expression of Na,K-ATPase (NKA) in gill and kidney of the pufferfish were examined and the osmolality, [Na + ] and [Cl] of the blood were assayed. The lowest levels of both relative protein abundance and activity were found to be exhibited in the BW group, and higher levels in the SW group than FW group. In all salinities, branchial NKA immunoreactivity was found in epithelial cells of the interlamellar region of the filament and not on the lamellae. Relative abundance of kidney NKA a-subunit, as well as the NKA activity, was found to be higher in the FW pufferfish than fish in BWor SW. Renal NKA appeared in the epithelial cells of distal tubules, proximal tubules, and collecting tubules, but not in glomeruli, in fish groups of various salinities. Plasma osmolality and chloride levels were significantly lower in FW pufferfish than those in BW and SW, whereas plasma sodium did not differ among the groups. Although identical distributions of NKAwere found in either gill or kidney of FW-, BW- or SW-acclimated spotted green pufferfish, differential NKA expression in fish of various salinity groups was associated with physiological homeostasis (stable blood osmolality), and illustrated the impressive osmoregulatory ability of this freshwater and estuarine species in response to salinity challenge. D 2004 Elsevier Inc. All rights reserved.

Comparison of the characteristics, functional properties, and in vitro hypoglycemic effects of various carrot insoluble fiber-rich fractions

Abstract: Fiber-rich fractions (FRFs) including insoluble dietary fiber (IDF), alcohol-insoluble solid (AIS), and water-insoluble solid (WIS) were isolated from carrot pomace via different methods. This study revealed that carrot pomace was rich in insoluble FRFs (50.1–67.4 g/100 g), which were mainly composed of pectic polysaccharides, hemicellulose, and cellulose. These insoluble FRFs, especially WIS, were found to have significantly (P<0.05) higher functional properties, glucose-adsorption capacity, and amylase-inhibition activity than those of cellulose. The ability of these FRFs to adsorb glucose and reduce amylase activity implied that they might help control post-prandial serum glucose level. Moreover, it was shown that the yield, composition, functional properties, and in vitro hypoglycemic effects among the three FRFs would be affected by their preparation methods. Our results recommended the consumption of these insoluble FRFs, especially WIS, as sources of food fibers or low calorie bulk ingredients in food applications requiring oil and moisture retention.

Upregulation of RANTES Gene Expression in Neuroglia by Japanese Encephalitis Virus Infection

Abstract: Infection with Japanese encephalitis virus (JEV) causes cerebral inflammation and stimulates inflammatory cytokine expression. Glial cells orchestrate immunocyte recruitment to focal sites of viral infection within the central nervous system (CNS) and synchronize immune cell functions through a regulated network of cytokines and chemokines. Since immune cell infiltration is prominent, we investigated the production of a responding chemoattractant, RANTES (regulated upon activation, normal T-cell expressed and secreted), in response to JEV infection of glial cells. Infection with JEV was found to elicit the production of RANTES from primary neurons/glia, mixed glia, microglia, and astrocytes but not from neuron cultures. The production of RANTES did not seem to be directly responsible for JEV-induced neuronal death but instead contributed to the recruitment of immune cells. RANTES expression required viral replication and the activation of extracellular signal-regulated kinase (ERK) as well as transcription factors, including nuclear factor kappa B (NF-κB) and nuclear factor IL-6 (NF-IL-6). The induction of RANTES expression by JEV infection in glial cells needed the coordinate activation of NF-κB and NF-IL-6. Using enzymatic inhibitors, we demonstrated a strong correlation between the ERK signaling pathway and RANTES expression. However, JEV replication was not dependent on the activation of ERK, NF-κB, and NF-IL-6. Altogether, these results demonstrated that infection of glial cells by JEV provided the early ERK-, NF-κB-, and NF-IL-6-mediated signals that directly activated RANTES expression, which might be involved in the initiation and amplification of inflammatory responses in the CNS.

Chitosan as Scaffold Materials: Effects of Molecular Weight and Degree of Deacetylation

Abstract: In this study, we investigated in vitro the role of the degree of deacetylation and molecular weight on some biological properties of chitosan films. The influence of different degree of deacetylation and molecular weight of chitosan on the hydrophilicity, degradation, mechanical properties and biocompatibility were evaluated. The results showed that the degree of deacetylation affected the hydrophilicity and biocompatibility of the chitosan films. The molecular weight, on the other hand, affected the rate of degradation and the mechanical properties. Chitosan with higher degree of deacetylation and molecular weight was more suitable for tissue engineering applications. Alginate could be added into chitosan to modify the rigidity and hydrophilicity of chitosan. Higher hydrophilicity, biocompatibility, and elongation were found after modification.

Insoluble fiber-rich fractions derived from Averrhoa carambola: hypoglycemic effects determined by in vitro methods.

Abstract: The hypoglycemic effects of several insoluble fiber-rich fractions (FRFs) including insoluble dietary fiber, alcohol-insoluble solid, and water-insoluble solid isolated from the pomace of Averrhoa carambola were investigated by some in vitro methods. This study evidenced that these three insoluble FRFs could effectively adsorb glucose, retard glucose diffusion, postpone the release of glucose from starch, and inhibit the activity of α-amylase to different extents. All of these mechanisms might create a concerted function in lowering the rate of glucose absorption and as a result decrease the postprandial serum glucose concentration. Our results revealed that the hypoglycemic effects of these insoluble FRFs were significantly (P<0.05) stronger than that of cellulose. Therefore, it was suggested that they could be incorporated as low-calorie bulk ingredients in high-fiber foods to reduce calorie level and help control blood glucose concentration.

Anti-invasive gene expression profile of curcumin in lung adenocarcinoma based on a high throughput microarray analysis.

Abstract: Curcumin has been reported to exhibit anti-invasive and/or antimetastatic activities, but the mechanism remains unclear. In this study, microarray analysis of gene expression profiles were used to characterize the anti-invasive mechanisms of curcumin in highly invasive lung adenocarcinoma cells (CL1-5). Results showed that curcumin significantly reduces the invasive capacity of CL1-5 cells in a concentration range far below its levels of cytotoxicity (20 microM) and that this anti-invasive effect was concentration dependent (10.17 +/- 0.76 x 10(3) cells at 0 microM; 5.67 +/- 1.53 x 10(3) cells at 1 microM; 2.67 +/- 0.58 x 10(3) cells at 5 microM; 1.15 +/- 1.03 x 10(3) cells at 10 microM; P < 0.05) in the Transwell cell culture chamber assay. Using microarray analysis, 81 genes were down-regulated and 71 genes were up-regulated after curcumin treatment. Below sublethal concentrations of curcumin (10 microM), several invasion-related genes were suppressed, including matrix metalloproteinase 14 (MMP14; 0.65-fold), neuronal cell adhesion molecule (0.54-fold), and integrins alpha6 (0.67-fold) and beta4 (0.63-fold). In addition, several heat-shock proteins (Hsp) [Hsp27 (2.78-fold), Hsp70 (3.75-fold), and Hsp40-like protein (3.21-fold)] were induced by curcumin. Real-time quantitative reverse transcription-polymerase chain reaction, Western blotting, and immunohistochemistry confirmed these results in both RNA and protein levels. Curcumin (1 to 10 microM) reduced the MMP14 expression in both mRNA and protein levels and also inhibited the activity of MMP2, the down-stream gelatinase of MMP14, by gelatin zymographic analysis. Based on these data, it can be concluded that curcumin might be an effective antimetastatic agent with a mechanism of anti-invasion via the regulation of certain gene expressions.

Aluminum complexes supported by tridentate aminophenoxide ligand as efficient catalysts for ring-opening polymerization of epsilon-caprolactone

Abstract: Aluminum complexes bearing dianionic amine bis(phenolate) ligand are described. Reactions of ligand precursors H2O2NMe or H2O2NPr [H2O2NMe = (CH3)N-(CH2-2-HO-3,5-C6H2(tBu)2)2; H2O2NPr = (CH3CH2CH2)N-(CH2-2-HO-3,5-C6H2(tBu)2)2] with 1.1 mol equiv of AlMe3 in toluene afford MeAl(O2NMe) (1) and MeAl(O2NPr) (2) as four-coordinate aluminum methyl complexes. The molecular structures are reported for compounds 1 and 2. Both compounds show excellent catalytic activity toward the ring-opening polymerization of e-caprolactone in the presence of benzyl alcohol.

Asymbiotic germination of immature seeds, plantlet development and ex vitro establishment of plants of dendrobium tosaense makino – a medicinally important orchid

Abstract: Shi-hu (Dendrobium spp. or Dendrobii Herba) is one of the important traditional Chinese medicines. The commercially available crude drug in the traditional medicine market is composed mainly of three species: Dendrobium tosaense, D. nobile, and D. moniliforme. An efficient method of propagation has been developed via asymbiotic germination of seeds in vitro for the medicinally important D. tosaense. Seeds from capsules of D. tosaense collected 8–14 wk after artificial pollination germinated after being cultured on full-strength or half-strength Murashige and Skoog (MS) medium devoid of plant growth regulators and with 3% sucrose. Germination of seeds varied with the medium type and seed maturity. Germinated seedlings after transfer to MS medium with 1.5% sucrose and 8% banana homogenate or potato juice or coconut water and 20 wk of incubation developed into healthy plantlets. Well-developed plantlets were transplanted to moss or moss and tree fern or tree fern as substrates in plastic trays and transferred to a greenhouse for hardening. All plants survived, attained maturity, and developed normal flower and capsule after one and a half years. This protocol of successful plant regeneration by asymbiotic seed germination should permit rapid propagation and conservation of this medicinally important Dendrobium species.

Constitution of stable artificial oil bodies with triacylglycerol, phospholipid, and caleosin.

Abstract: Seed oil bodies are lipid storage organelles of 0.5-2 microm in diameter and comprise a triacylglycerol matrix shielded by a monolayer of phospholipids and proteins. These proteins include abundant structural proteins, oleosins, and at least two minor proteins termed caleosin and steroleosin. This study examined if artificial oil bodies (AOBs) composed of triacylglycerol and phospholipid could be stabilized by oleosin, caleosin, or steroleosin. Our results showed that stabilization effects could be realized by oleosin or caleosin but not by steroleosin. The sizes of the AOBs constituted with oleosin (0.5-2 microm) or caleosin (50-200 nm) were similar to or 10 times smaller than those of the native oil bodies. Recombinant caleosin expressed in Escherichia coli also encapsulated AOBs with a size, topology, and stability comparable to those encapsulated with native caleosin. A proteinase K digestion indicated that caleosin anchored the AOBs via its central hydrophobic domain of approximately 4 kDa. Isoelectrofocusing revealed that the isoelectric point of the caleosin-stabilized AOBs was pH 4.0. Aggregation of AOBs was observed at a pH lower than 4.5; thus, their stability and integrity were presumably contributed by surface caleosin via electronegative repulsion and steric hindrance. The caleosin-stabilized AOBs were thermostable up to 70 degrees C and potentially useful for biotechnological applications.

On-line personalized sales promotion in electronic commerce

Abstract: Electronic Commerce encompasses all electronically conducted business activities, operations, and transaction processing. With the development of electronic commerce in the Internet, companies have changed the way they connect to and deal with their customers and partners. Businesses now could overcome the space and time barriers and are capable of serving customers electronically and intelligently. However, it is quite a great challenge to attract and retain the customers over Internet due to the low barrier of entrance and severe competition. Personalization, a special form of differentiation, when applied in market fragmentation can transform a standard product or service into a specialized solution for an individual. In this research, an on-line personalized sales promotion decision support system is proposed. The proposed system consists of three modules: (1) marketing strategies, (2) promotion patterns model, and (3) personalized promotion products. The marketing strategies contain sales promotion strategies and pricing strategies. Promotion patterns are generated according to various sales promotion strategies, and the promoted prices for the promotion products are generated by considering both the current stages of business life cycle and product life cycle. In the promotion patterns model, by segmenting the market, customer behaviors of three categories can be analyzed by utilizing data mining techniques and statistical analysis to generate personalized candidate promotion products. Finally, multiple evaluation indicators are used and adjusted to rank and obtain the final personalized promotion products. With the promotion products based on customers' past frequent purchase patterns, it has the potential to increase the success rate of promotion, customer satisfaction, and loyalty. In this paper, a prototype system was developed to illustrate how the proposed on-line personalized promotion decision support system works in electronic commerce and a simplified case of performance analysis was conducted for evaluation.