Showing papers by "National Tsing Hua University published in 2004"
TL;DR: A new approach for the design of alloys is presented in this paper, where high-entropy alloys with multi-principal elements were synthesized using well-developed processing technologies.
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.
8,175 citations
TL;DR: This work provides a probabilistic derivation for the classic, incidence-based forms of Jaccard and Sorensen indices of compositional similarity and proposes estimators for these indices that include the effect of unseen shared species, based on either (replicated) incidence- or abundancebased sample data.
Abstract: The classic Jaccard and Sorensen indices of compositional similarity (and other indices that depend upon the same variables) are notoriously sensitive to sample size, especially for assemblages with numerous rare species. Further, because these indices are based solely on presence–absence data, accurate estimators for them are unattainable. We provide a probabilistic derivation for the classic, incidence-based forms of these indices and extend this approach to formulate new Jaccard-type or Sorensen-type indices based on species abundance data. We then propose estimators for these indices that include the effect of unseen shared species, based on either (replicated) incidence- or abundancebased sample data. In sampling simulations, these new estimators prove to be considerably less biased than classic indices when a substantial proportion of species are missing from samples. Based on species-rich empirical datasets, we show how incorporating the effect of unseen shared species not only increases accuracy but also can change the interpretation of results.
1,672 citations
TL;DR: It is found that rice (Oryza sativa) has nearly twice as many RLK/Pelle members as Arabidopsis does, and it is not simply a consequence of a larger predicted gene number in rice.
Abstract: Receptor-like kinases (RLKs) belong to the large RLK/Pelle gene family, and it is known that the Arabidopsis thaliana genome contains >600 such members, which play important roles in plant growth, development, and defense responses. Surprisingly, we found that rice (Oryza sativa) has nearly twice as many RLK/Pelle members as Arabidopsis does, and it is not simply a consequence of a larger predicted gene number in rice. From the inferred phylogeny of all Arabidopsis and rice RLK/Pelle members, we estimated that the common ancestor of Arabidopsis and rice had >440 RLK/Pelles and that large-scale expansions of certain RLK/Pelle members and fusions of novel domains have occurred in both the Arabidopsis and rice lineages since their divergence. In addition, the extracellular domains have higher nonsynonymous substitution rates than the intracellular domains, consistent with the role of extracellular domains in sensing diverse signals. The lineage-specific expansions in Arabidopsis can be attributed to both tandem and large-scale duplications, whereas tandem duplication seems to be the major mechanism for recent expansions in rice. Interestingly, although the RLKs that are involved in development seem to have rarely been duplicated after the Arabidopsis–rice split, those that are involved in defense/disease resistance apparently have undergone many duplication events. These findings led us to hypothesize that most of the recent expansions of the RLK/Pelle family have involved defense/resistance-related genes.
986 citations
TL;DR: The results clearly suggested that the genipin-cross-linked NOCC/alginate hydrogel could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine.
829 citations
TL;DR: In this article, four alloys containing multiprincipal metallic elements (≥5 elements) were prepared by casting, splat quenching, and sputtering, and their microstructures and crystal structures were investigated.
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.
824 citations
TL;DR: The results indicate that GFP‐positive cells in transgenic animals accurately represent neural stem and progenitor cells and suggest that these nestin‐GFP–expressing cells encompass the majority of the neural stem cells in the adult brain.
Abstract: Neural stem cells generate a wide spectrum of cell types in developing and adult nervous systems. These cells are marked by expression of the intermediate filament nestin. We used the regulatory elements of the nestin gene to generate transgenic mice in which neural stem cells of the embryonic and adult brain are marked by the expression of green fluorescent protein (GFP). We used these animals as a reporter line for studying neural stem and progenitor cells in the developing and adult nervous systems. In these nestin-GFP animals, we found that GFP-positive cells reflect the distribution of nestin-positive cells and accurately mark the neurogenic areas of the adult brain. Nestin-GFP cells can be isolated with high purity by using fluorescent-activated cell sorting and can generate multipotential neurospheres. In the adult brain, nestin-GFP cells are approximately 1,400-fold more efficient in generating neurospheres than are GFP-negative cells and, despite their small number, give rise to 70 times more neurospheres than does the GFP-negative population. We characterized the expression of a panel of differentiation markers in GFP-positive cells in the nestin-GFP transgenics and found that these cells can be divided into two groups based on the strength of their GFP signal: GFP-bright cells express glial fibrillary acidic protein (GFAP) but not betaIII-tubulin, whereas GFP-dim cells express betaIII-tubulin but not GFAP. These two classes of cells represent distinct classes of neuronal precursors in the adult mammalian brain, and may reflect different stages of neuronal differentiation. We also found unusual features of nestin-GFP-positive cells in the subgranular cell layer of the dentate gyrus. Together, our results indicate that GFP-positive cells in our transgenic animals accurately represent neural stem and progenitor cells and suggest that these nestin-GFP-expressing cells encompass the majority of the neural stem cells in the adult brain.
667 citations
TL;DR: In this paper, multi-principal element alloy coatings of Al-Si alloys were prepared by a plasma spray method and they not only exhibited a good oxidation resistance up to 1000 °C, but also possessed an excellent abrasive wear resistance approximately two times higher than those of SUJ2 and SKD61.
Abstract: Multi-principal-element alloy coatings of Al-Si alloys were prepared by a plasma spray method They not only exhibited a good oxidation resistance up to 1000 °C, but also possessed an excellent abrasive wear resistance approximately two times higher than those of SUJ2 and SKD61 Moreover, they displayed a high temperature precipitation hardening phenomenon up to 1100 °C which is novel and seldom found in conventional alloys
573 citations
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TL;DR: Molecular studies of a handful of genes that are involved in maintaining reproductive isolation between species have provided some striking insights, suggesting that despite being strongly influenced by positive selection, speciation genes are often non-essential, having functions that are only loosely coupled to reproductive isolation.
Abstract: It is only in the past five years that studies of speciation have truly entered the molecular era. Recent molecular analyses of a handful of genes that are involved in maintaining reproductive isolation between species (speciation genes) have provided some striking insights. In particular, it seems that despite being strongly influenced by positive selection, speciation genes are often non-essential, having functions that are only loosely coupled to reproductive isolation. Molecular studies might also resolve the long-running debate on the relative importance of allopatric and parapatric modes of speciation.
529 citations
TL;DR: In this paper, the wear resistance and high-temperature compression strength of CuCoNiCrAl0.5Fe alloy with various amounts of boron addition were discussed.
Abstract: This study discusses the wear resistance and high-temperature compression strength of CuCoNiCrAl0.5Fe alloy with various amounts of boron addition. Experiments show that within the atomic ratio of boron addition from x=0 to x=1.0 in CuCoNiCrAl0.5FeBx (referred to as B-0 to B-1.0 alloys), the alloys are of fcc structure with boride precipitation. The volume fraction of borides increases with increasing boron addition. The corresponding hardness increases from HV 232 to HV 736. Wear resistance and high-temperature compression strength are significantly enhanced by the formation of boride. The alloys with boride are less tough. The superior wear resistance of B-1.0 alloy, which is even better than SUJ2 wear-resistant steel, indicates that the CuCoNiCrAl0.5FeBx alloys have potential applications as ambient- and high-temperature mold, tool, and structural materials.
493 citations
TL;DR: The electron cyclotron maser (ECM) as mentioned in this paper is based on a stimulated cyclogron emission process involving energetic electrons in gyrational motion, which constitutes a cornerstone of relativistic electronics.
Abstract: The electron cyclotron maser (ECM) is based on a stimulated cyclotron emission process involving energetic electrons in gyrational motion. It constitutes a cornerstone of relativistic electronics, a discipline that has emerged from our understanding and utilization of relativistic effects for the generation of coherent radiation from free electrons. Over a span of four decades, the ECM has undergone a remarkably successful evolution from basic research to device implementation while continuously being enriched by new physical insights. By delivering unprecedented power levels, ECM-based devices have occupied a unique position in the millimeter and submillimeter regions of the electromagnetic spectrum, and find use in numerous applications such as fusion plasma heating, advanced radars, industrial processing, materials characterization, particle acceleration, and tracking of space objects. This article presents a comprehensive review of the fundamental principles of the ECM and their embodiment in practical devices.
492 citations
TL;DR: A cell-based assay was developed to screen existing drugs, natural products, and synthetic compounds to identify effective anti-SARS agents, and of particular interest are the two anti-HIV agents, one as an entry blocker and the other as a 3CL protease inhibitor.
Abstract: Severe acute respiratory syndrome (SARS) is an infectious disease caused by a novel human coronavirus. Currently, no effective antiviral agents exist against this type of virus. A cell-based assay, with SARS virus and Vero E6 cells, was developed to screen existing drugs, natural products, and synthetic compounds to identify effective anti-SARS agents. Of >10,000 agents tested, ≈50 compounds were found active at 10 μM; among these compounds, two are existing drugs (Reserpine 13 and Aescin 5) and several are in clinical development. These 50 active compounds were tested again, and compounds 2–6, 10, and 13 showed active at 3 μM. The 50% inhibitory concentrations for the inhibition of viral replication (EC50) and host growth (CC50) were then measured and the selectivity index (SI = CC50/EC50) was determined. The EC50, based on ELISA, and SI for Reserpine, Aescim, and Valinomycin are 3.4 μM (SI = 7.3), 6.0 μM (SI = 2.5), and 0.85 μM (SI = 80), respectively. Additional studies were carried out to further understand the mode of action of some active compounds, including ELISA, Western blot analysis, immunofluorescence and flow cytometry assays, and inhibition against the 3CL protease and viral entry. Of particular interest are the two anti-HIV agents, one as an entry blocker and the other as a 3CL protease inhibitor (Ki = 0.6 μM).
Eötvös Loránd University1, Leipzig University2, Sapienza University of Rome3, University of L'Aquila4, New Bulgarian University5, University of California, San Diego6, National Yang-Ming University7, Budapest University of Technology and Economics8, University of Illinois at Urbana–Champaign9, National Tsing Hua University10, University of Minnesota11, Chung Yuan Christian University12, Washington University in St. Louis13
TL;DR: New on-line resources that the project has compiled and made available to researchers on the world wide web are described at http://crl.ucsd.edu/~aszekely/ipnp/.
TL;DR: In this paper, the hysteresis curves of the two high-entropy alloys in reactive sputtering are quite different in comparison to those of elements or simple alloys.
Abstract: Multi-element high-entropy alloys are alloy systems with n (5≤n≤13) principal elements each having an atomic percentage no more than 35%. Using the alloys of Fe-Co-Ni-Cr-Cu-Al-Mn and Fe-Co-Ni-Cr-Cu-Al0.5 as target material in reactive sputtering, nitride films were deposited. The hysteresis curves of the two high-entropy alloys in reactive sputtering are quite different in comparison to those of elements or simple alloys. The film deposition rate decreased with increasing nitrogen gas flow and the highest film thickness was in excess of 2.5 μm. The alloy films are crystalline with structures of a mixed FCC and BCC or simple FCC solid solution, while the crystallinity of the nitride films decreased and approached amorphous with increasing nitrogen gas flow. The composition of the alloy films was similar to their original targets, and the nitrogen content of the nitride films increased with increasing nitrogen flow, to a maximum of 41.1 at.% nitrogen. The values of resistivity of the two alloy films were 108 and 135 μΩ cm, respectively, and those of their nitride films increased with nitrogen flow, to a factor of 3 of the alloy film. The rms surface roughness measured by AFM decreased significantly from 9 to 13 nm for the alloy films to only 1–3 nm for the nitride films. Values of hardness are about 4 GPa for alloy films and about 11 GPa for nitride films. The growth rate, the resistivity, and the hardness of the resulting nitride films were not affected too much by substrate bias due to the amorphous nature of the nitride films.
TL;DR: In this paper, the stochastic H/sub 2/H/sub /spl infin// control problem with state-dependent noise is discussed, and an observer-based suboptimal control algorithm is proposed.
Abstract: This paper discusses the stochastic H/sub 2//H/sub /spl infin// control problem with state-dependent noise By means of the stabilization, exact observability and stochastic detectability of stochastic systems, the infinite horizon stochastic H/sub 2//H/sub /spl infin// control design is developed For the finite horizon H/sub 2//H/sub /spl infin// control problem, our results generalize the corresponding deterministic ones to the stochastic models Finally, the observer-based suboptimal stochastic H/sub 2//H/sub /spl infin// control is discussed in which the state variables cannot be measured directly, and a feasible design algorithm is proposed
TL;DR: A method for immobilization of Candida rugosa lipase to two types of chitosan beads by activating the hydroxyl groups of ch itosan using carbodiimide coupling agent has been successfully developed.
TL;DR: In this article, an ultrasonic C-Scan to examine the delamination of carbon fiber-reinforced plastic (CFRP) laminate is used in the use of twist drill, candle stick drill and saw drill.
Abstract: This paper presents a prediction and evaluation of delamination factor in use of twist drill, candle stick drill and saw drill. The approach is based on Taguchi’s method and the analysis of variance (ANOVA). An ultrasonic C-Scan to examine the delamination of carbon fiber-reinforced plastic (CFRP) laminate is used in this paper. The experiments were conducted to study the delamination factor under various cutting conditions. The experimental results indicate that the feed rate and the drill diameter are recognized to make the most significant contribution to the overall performance. The objective was to establish a correlation between feed rate, spindle speed and drill diameter with the induced delamination in a CFRP laminate. The correlation was obtained by multi-variable linear regression and compared with the experimental results.
TL;DR: The findings suggest that despite the lack of lexical tone contrasts in the French language, French listeners are not absolutely “deaf” to tonal variations, they simply fail to perceive tones along the lines of a well-defined and finite set of linguistic categories.
TL;DR: The PCA analysis confirmed that petrochemical industrial parks located in the vicinity of estuary of Gao-ping River might be the possible source for the PAH input.
TL;DR: This article found that correcting students improved in accuracy over the course of a study and attributed observed gains to correction by including a comparison group that received little or no correction, but they did not consider the effect of other factors such as writing practice, input obtained in the class, or outside exposure.
TL;DR: In this paper, multiwalled carbon nanotubes (MWNTs) grafted with poly(methyl methacrylate) (PMMA) were synthesized by emulsion reactions and used as a reinforcement for commercial PMMA.
Abstract: Multiwalled carbon nanotubes (MWNTs) grafted with poly(methyl methacrylate) (PMMA) were synthesized by emulsion reactions and used as a reinforcement for commercial PMMA. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the applied tensile load on the composites was transferred to the PMMA-grafted MWNTs, leading to a strain failure of the MWNTs rather than an adhesive failure between the MWNTs and the matrix. Dynamic mechanical analysis (DMA) data showed that the storage modulus at 20 °C of the PMMA composite containing 20 wt.-% of the PMMA-grafted MWNTs was significantly enhanced by ∼ 29 GPa (or by ∼ 1100 %) as compared with commercial PMMA.
TL;DR: The entire DNA sequence of pLVPK, which is a 219-kb virulence plasmid harbored in a bacteremic isolate of Klebsiella pneumoniae, is determined and the presence of 13 insertion sequences located mostly at the boundaries of the aforementioned gene clusters suggests that pL VPK was derived from a sequential assembly of various horizontally acquired DNA fragments.
TL;DR: An unremovable spectral theorem and a stochastic Popov-Belevith-Hautus Criterion for exact observability and a comparison theorem for stochastically algebraic Riccati equations and a result on Lyapunov-type equations are obtained.
TL;DR: In this paper, a two-step approach to functionalize gold nanoparticles prepared by reducing tetrachloroauric acid by trisodium citrate in water is proposed, where the chloride and citrate physisorbed on the gold nanoparticle are first displaced by thioctic acid (TA), which is then exchanged by thiols containing the desired functionality during the second step.
Abstract: We propose a two-step approach to functionalize gold nanoparticles prepared by reducing tetrachloroauric acid by trisodium citrate in water. The chloride and citrate physisorbed on the gold nanoparticles are first displaced by thioctic acid (TA), which is then exchanged by thiols containing the desired functionality during the second step. TA bears a carboxylate group and disulfide; at high pH, the negative charge of the former stabilizes gold nanoparticles and the disulfide develops two S−Au bonds, retarding the desorption kinetics upon further functionalization. The slow kinetics of TA desorption is crucial to establishing sufficient steric stabilization for the gold core while losing electrostatic stabilization. Successful attachment of carboxylate, crown ether, cyclodextrin, pyridine, and amino functionalities is verified by surface sensitive techniques. In most cases, ca. 80% of the TA molecules are displaced. The nanoparticles are stable under solution pH where the surface group is ionized. Although...
TL;DR: It was shown in the in vitro degradation study that after fixing with genipin, the resistance against enzymatic degradation of the acellular tissue increased significantly with increasing its crosslinking degree.
TL;DR: Electrowetting on dielectric and dielectrophoretic electromechanical mechanisms dominate microfluidic actuation in the low- and high-frequency limits, respectively and a saturation phenomenon is observed which exhibits a weak dependence on frequency and is probably correlated to contact angle saturation.
Abstract: Electrowetting on dielectric and dielectrophoretic electromechanical mechanisms dominate microfluidic actuation in the low- and high-frequency limits, respectively. The frequency-dependent relationship between these two mechanisms has been clarified by the Maxwell stress tensor and a simple RC circuit model. In this paper, we report extensive height-of-rise measurements obtained with vertical, parallel, dielectrically coated electrodes to test this relationship using deionized water and solutions containing sugar and salt. For DC and AC (20 Hz to 20 kHz) voltage magnitudes up to ∼150 V-rms, the data are highly reproducible and, within experimental error, consistent with the square-law predictions of the model. Eventually as voltage is increased, a saturation phenomenon is observed which exhibits a weak dependence on frequency and is probably correlated to contact angle saturation.
TL;DR: Ten phosphatized specimens of a small animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, and provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.
Abstract: Ten phosphatized specimens of a small (<180 micrometers) animal displaying clear bilaterian features have been recovered from the Doushantuo Formation, China, dating from 40 to 55 million years before the Cambrian. Seen in sections, this animal (Vernanimalcula guizhouena gen. et sp. nov.) had paired coeloms extending the length of the gut; paired external pits that could be sense organs; bilateral, anterior-posterior organization; a ventrally directed anterior mouth with thick walled pharynx; and a triploblastic structure. The structural complexity is that of an adult rather than a larval form. These fossils provide the first evidence confirming the phylogenetic inference that Bilateria arose well before the Cambrian.
TL;DR: It is found that crosslinking gelatin hydrogels with carbodiimide or genipin could produce distinct crossl linking structures because of the differences in theirCrosslinking types.
Abstract: It was suggested in our previous studies that carbodiimide- and genipin-crosslinked gelatin hydrogels could be used as bioadhesives to overcome the cytotoxicity problem associated with formaldehyde-crosslinked gelatin hydrogels. In this study, we investigated the crosslinking structures of carbodiimide- and genipin-crosslinked gelatin hydrogels. We found that crosslinking gelatin hydrogels with carbodiimide or genipin could produce distinct crosslinking structures because of the differences in their crosslinking types. Carbodiimide could form intramolecular crosslinks within a gelatin molecule or short-range intermolecular crosslinks between two adjacent gelatin molecules. On the basis of gel permeation chromatography, we found that the polymerization of genipin molecules could occur under the conditions used in crosslinking gelatin hydrogels via a possible aldol condensation. Therefore, besides intramolecular and short-range intermolecular crosslinks, additional long-range intermolecular crosslinks could be introduced into genipin-crosslinked gelatin hydrogels. Crosslinking a gelatin hydrogel with carbodiimide was more rapid than crosslinking with genipin. Therefore, the gelation time for the carbodiimide-crosslinked gelatin hydrogels was significantly shorter than that of the genipin-crosslinked gelatin hydrogels. However, the cohesive (interconnected) structure of the carbodiimide-crosslinked gelatin hydrogels was readily broken because, unlike the genipin-crosslinked gelatin hydrogels, there were simply intramolecular and short-range intermolecular crosslinks present in the carbodiimide-crosslinked hydrogel. In the cytotoxicity study, the carbodiimide-crosslinked gelatin hydrogels were dissolved into small fragments in the cultural medium within 10 min. In contrast, the genipin-crosslinked gelatin hydrogels remained intact in the medium throughout the entire course of the study. Again, this may be attributed to the differences in their crosslinking structures. The genipin-crosslinked gelatin hydrogels were less cytotoxic than the carbodiimide-crosslinked gelatin hydrogels. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 4017–4026, 2004
TL;DR: A hierarchical attribute structure is proposed to evaluate ERP projects systematically and fuzzy set theory is used to aggregate the linguistic evaluation descriptions and weights.
Patent•
09 Dec 2004TL;DR: In this paper, the authors describe a memory cell structure and process to fabricate chalcogenide phase change memory, which produces a small cross-sectional area of a chalgogenide-electrode contact part of the phase change memories.
Abstract: The invention relates to a novel memory cell structure and process to fabricate chalcogenide phase change memory. More particularly, it produces a small cross-sectional area of a chalcogenide-electrode contact part of the phase change memory, which affects the current/power requirement of the chalcogenide memory. Particular aspects of the present invention are described in the claims, specification and drawings.
TL;DR: The methylcellulose/alginate hydrogel blended with NaCl could be a suitable carrier for site-specific protein drug delivery in the intestine by minimizing degradation of the protein drug while achieving a high loading efficiency.