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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Analytical chemistry 63 (1991), S. 2939-2946 
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 99-100 (July 2004), p. 203-208 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: A TGA assisted hydrothermal process was employed to prepare chalcogenide nanorods. The different morphology of CdS nanomaterials prepared with and without the TGA assisted hydrothermal process indicates that TGA plays a critical role in controlling the nucleation and growth of CdS nanomaterials. The paper makes a preliminary presentation of the mechanisms of preparation of chalcogenide nanostructures with and without the use of the TGA assisted hydrothermal synthesis. FeS nanorods and nanoparticles have been prepared by the TGA assisted and without the TGA assisted hydrothermal process, respectively, which confirmed the proposed mechanism. X-ray diffraction (XRD) shows that the nanorods are of orthorhombic structure, and selected area electron diffraction (SAED) pattern showed that the FeS nanorods were single crystalse. Further investigation for the synthesis of other chalcogenides will be undertaken in orderto confirm the proposed mechanism
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 340-341 (June 2007), p. 421-428 
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Fretting fatigue has grasped strong interest in last decades, some quantitative methods forthe evaluation of fretting fatigue were developed. However, only very few studies have beenreported on fretting wear, especially on its mechanical model and evaluation method. In this study,cumulative plastic strain is analyzed by FEM. To obtain accurate plastic strain, the shape changedue to the plastic deformation has been taken into account. It is found that the cumulative plasticstrain will be saturated after several hundred cycles at the initial fretting stage. Considering thatfretting wear is very small during this early stage, as it can be observed from the fretting test, thewear at the contact interface before the saturation of cumulative plastic strain can be neglected.Since the saturated cumulative plastic deformation represents the stable deformation of the contactinterface, it is proposed that the fretting wear can be characterized by the saturated cumulativeplastic strain and accumulative shear stress. With this method, the wear profile of the specimen ispredicted. By comparing FEM results with the experimental results of fretting wear, the proposedwear formulation is validated
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Numerische Mathematik 63 (1992), S. 123-144 
    ISSN: 0945-3245
    Keywords: 65N30 ; 65N13 ; 65F10
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary Anti-derivatives of wavelets are used for the numerical solution of differential equations. Optimal error estimates are obtained in the applications to two-point boundary value problems of second order. The orthogonal property of the wavelets is used to construct efficient iterative methods for the solution of the resultant linear algebraic systems. Numerical examples are given.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. ; Stafa-Zurich, Switzerland
    Solid state phenomena Vol. 99-100 (July 2004), p. 197-202 
    ISSN: 1662-9779
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Physics
    Notes: Star-shaped and rod-like PbS crystals have been successfully prepared by a novelthioglycolic acid (TGA) assisted hydrothermal method. X-ray diffraction (XRD) reveals that the PbS crystals are of the cubic rock-salt structure and well formed. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) observations show that the morphology of PbS nanocrystals is easily controlled according to sulphur source, lead source, and pH value. Furthermore, the paper gives a preliminary presntation of the mechanism and the critical role of theTGA-assisted hydrothermal synthesis of PbS nanorods
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 58 (2005), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Human pathogen Pseudomonas aeruginosa uses quorum-sensing (QS) signalling systems to synchronize the production of virulence factors. There are two interrelated QS systems, las and rhl, in P. aeruginosa. In addition to this complexity, a number of transcriptional regulators were shown to have complicated interplays with las and rhl central QS components. Here, we describe a novel virulence and QS modulator (VqsM) that positively regulates the QS systems in P. aeruginosa. Mutation in vqsM resulted in much reduced production of N-acylhomoserine lactones (AHLs) and extracellular enzymes. Sequence analysis revealed that vqsM encodes a transcriptional regulator with an AraC-type helix–turn–helix DNA binding domain at the C-terminal of the peptide. Global gene expression profile analysis showed at least a total of 302 genes to be influenced, directly or indirectly, by VqsM. Among the 203 VqsM-promoted genes, 52.2% were known to be QS upregulated. Several genes encoding the key regulators implicated in QS, such as rhlR, rsaL, vqsR, mvfR, pprB and rpoS, and two AHL synthesis genes, lasI and rhlI, were suppressed in the vqsM mutant. Similar to the ‘AHL-blind’ phenotype of vqsR and pprB mutants, vqsM mutant did not respond to external addition of N-3-oxo-dodecanoyl-homoserine lactone signals. Moreover, overexpression of vqsR in vqsM mutant more or less restored the production of both AHL and virulence factors. The results demonstrate that VqsM, largely through modulation of vqsR expression, plays a vital role in regulation of QS signalling in P. aeruginosa.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: N -acylhomoserine lactones (AHLs) are used as signal molecules by many quorum-sensing Proteobacteria. Diverse plant and animal pathogens use AHLs to regulate infection and virulence functions. These signals are subject to biological inactivation by AHL-lactonases and AHL-acylases. Previously, little was known about the molecular details underlying the latter mechanism. An AHL signal-inactivating bacterium, identified as a Ralstonia sp., was isolated from a mixed-species biofilm. The signal inactivation encoding gene from this organism, which we call aiiD , was cloned and successfully expressed in Escherichia coli and inactivated three AHLs tested. The predicted 794-amino-acid polypeptide was most similar to the aculeacin A acylase (AAC) from Actinoplanes utahensis and also shared significant similarities with cephalosporin acylases and other N-terminal (Ntn) hydrolases. However, the most similar homologues of AiiD are deduced proteins of undemonstrated function from available Ralstonia , Deinococcus and Pseudomonas genomes. LC-MS analyses demonstrated that AiiD hydrolyses the AHL amide, releasing homoserine lactone and the corresponding fatty acid. Expression of AiiD in Pseudomonas aeruginosa PAO1 quenched quorum sensing by this bacterium, decreasing its ability to swarm, produce elastase and pyocyanin and to paralyse nematodes. Thus, AHL-acylases have fundamental implications and hold biotechnological promise in quenching quorum sensing.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 50 (2003), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Trimeric G-proteins transmit extracellular signals to various downstream effectors (e.g. MAP kinases) in eukaryotes. In the rice blast fungus Magnaporthe grisea, the Pmk1 MAP kinase is essential for appressorium formation and infectious growth. The pmk1 deletion mutant fails to form appressoria but still responds to exogenous cAMP for tip deformation. Since gene disruption mutants of three Gα subunits still form appressoria and are phenotypically different from pmk1 mutants, it is likely that the Pmk1 pathway is activated by Gβ in M. grisea. In this study, we isolated and characterized the MGB1 gene that encodes the G subunit in M. grisea. Mutants disrupted in MGB1 were reduced in conidiation. Conidia from mgb1 mutants were defective in appressorium formation and failed to penetrate or grow invasively on rice leaves. Exogenous cAMP induced appressorium formation in mgb1 mutants, but these appressoria were abnormal in shape and could not penetrate. The intracellular cAMP level was reduced in mgb1 mutants and the defects in conidiation and hyphal growth were partially suppressed with 1 mM cAMP. Transformants expressing multiple copies of MGB1 were able to form appressoria on hydrophilic surfaces. Our results suggest that MGB1 may be involved in the cAMP signalling for regulating conidiation, surface recognition and appressorium formation. The Pmk1 pathway may be the downstream target of MGB1 for regulating penetration and infectious hyphae growth in M. grisea.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Bacterial cells sense their population density through a sophisticated cell–cell communication system and trigger expression of particular genes when the density reaches a threshold. This type of gene regulation, which controls diverse biological functions including virulence, is known as ...
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Magnaporthe grisea is the most destructive pathogen of rice worldwide and the principal model organism for elucidating the molecular basis of fungal disease of plants. Here, we report the draft sequence of the M. grisea genome. Analysis of the gene set provides an insight into the adaptations ...
    Type of Medium: Electronic Resource
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