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排序方式: 共有1496条查询结果,搜索用时 15 毫秒
981.
J. Michael Conlon Laura K. Reinert Milena Mechkarska Manju Prajeep Mohammed A. Meetani Laurent Coquet Thierry Jouenne Marc P. Hayes Gretchen Padgett-Flohr Louise A. Rollins-Smith 《Journal of chemical ecology》2013,39(6):797-805
Population declines due to amphibian chytridiomycosis among selected species of ranid frogs from western North America have been severe, but there is evidence that the Oregon spotted frog, Rana pretiosa Baird and Girard, 1853, displays resistance to the disease. Norepinephrine-stimulated skin secretions were collected from a non-declining population of R. pretiosa that had been exposed to the causative agent Batrachochytrium dendrobatidis. Peptidomic analysis led to identification and isolation, in pure form, of a total of 18 host-defense peptides that were characterized structurally. Brevinin-1PRa, -1PRb, -1PRc, and -1PRd, esculentin-2PRa and -PRb, ranatuerin-2PRa, -2PRb, -2PRc, and -2PRe, temporin-PRb and -PRc were identified in an earlier study of skin secretions of frogs from a different population of R. pretiosa known to be declining. Ranatuerin-2PRf, -2PRg, -2PRh, temporin-PRd, -PRe, and -PRf were not identified in skin secretions from frogs from the declining population, whereas temporin-PRa and ranatuerin-2PRd, present in skin secretions from the declining population, were not detected in the current study. All purified peptides inhibited the growth of B. dendrobatidis zoospores. Peptides of the brevinin-1 and esculentin-2 families displayed the highest potency (minimum inhibitory concentration = 6.25–12.5 μM). The study provides support for the hypothesis that the multiplicity and diversity of the antimicrobial peptide repertoire in R. pretiosa and the high growth-inhibitory potency of certain peptides against B. dendrobatidis are important in conferring a measure of resistance to fatal chytridiomycosis. 相似文献
982.
Justine Dionne Thierry Lefèvre Michèle Auger 《International journal of molecular sciences》2016,17(8)
To plentifully benefit from its properties (mechanical, optical, biological) and its potential to manufacture green materials, the structure of spider silk has to be known accurately. To this aim, the major ampullate (MA) silk of Araneus diadematus (AD) and Nephila clavipes (NC) has been compared quantitatively in the liquid and fiber states using Raman spectromicroscopy. The data show that the spidroin conformations of the two dopes are indistinguishable despite their specific amino acid composition. This result suggests that GlyGlyX and GlyProGlyXX amino acid motifs (X = Leu, Glu, Tyr, Ser, etc.) are conformationally equivalent due to the chain flexibility in the aqueous environment. Species-related sequence specificity is expressed more extensively in the fiber: the β-sheet content is lower and width of the orientation distribution of the carbonyl groups is broader for AD (29% and 58°, respectively) as compared to NC (37% and 51°, respectively). β-Sheet content values are close to the proportion of polyalanine segments, suggesting that β-sheet formation is mainly dictated by the spidroin sequence. The extent of molecular alignment seems to be related to the presence of proline (Pro) that may decrease conformational flexibility and inhibit chain extension and alignment upon drawing. It appears that besides the presence of Pro, secondary structure and molecular orientation contribute to the different mechanical properties of MA threads. 相似文献
983.
984.
Thierry Serre Loïc Lalys Christophe Bartoli Amandine Christia-Lotter Georges Leonetti Christian Brunet 《Accident; analysis and prevention》2010,42(6):1943-1948
This paper highlights the potential impact points of a child pedestrian during a crash with the front end of a vehicle. Child anthropometry was defined for ages between 3 and 15 years. It was based on the measurement of seven different segment body heights (knee, femur, pelvis, shoulder, neck, chin, vertex) performed on about 2,000 French children. For each dimension, the 5th, 50th and 95th percentile values were reported, and the corresponding linear regression lines were given. Then these heights were confronted with three different vehicle shapes, corresponding to a passenger car, a sport utility vehicle and a light truck, to identify impact points. In particular, we show that the thigh is directly hit by the bumper for children above 12 years of age, whereas the head principally impacts the hood. The influence of child anthropometry on the pedestrian trajectory and the comparison with test procedures in regulation are discussed. 相似文献
985.
Investigations on high temperature polyimide potentialities for silicon carbide power device passivation 总被引:1,自引:0,他引:1
Samir Zelmat Marie-Laure Locatelli Thierry Lebey Sombel Diaham 《Microelectronic Engineering》2006,83(1):51-54
The operation of silicon carbide (SiC) power devices under severe conditions requires the development of thermally, electrically and chemically stable package. Passivation layer provides electrical insulation and environmental protection for the SiC die. As higher junction temperature and higher electric field can be reached within SiC component, consideration must be given to the thermal stability of the dielectric properties of the material in the die surrounding. Due to their supposed high operating temperature and dielectric strength, spin coated polyimide materials appear as a possible candidate for such passivation and insulation purposes. In this paper, we study the potentialities of a high temperature polyimide from HD Microsystems, for SiC power device passivation, at temperature up to 300 °C. 相似文献
986.
We study the Hall effect in a system of weakly coupled Luttinger Liquid chains, using a Memory function approach to compute
the Hall constant in the presence of umklapp scattering along the chains. In this approximation, the Hall constant decomposes
into two terms: a high-frequency term and a Memory function term. For the case of zero umklapp scattering, where the Memory
function vanishes, the Hall constant is simply the band value, in agreement with former results in a similar model with no
dissipation along the chains. With umklapp scattering along the chains, we find a power-law temperature dependance of the
Hall constant. We discuss the applications to quasi 1D organic conductors at high temperatures. 相似文献
987.
P. Lafitte Lionel Valenti† Lydia Casciani† Thierry Hoarau E. Lomonte† Frédéric Maccario† Jean-François Nicola 《International journal of cosmetic science》2009,31(3):243-243
Citation: IFSCC Magazine , 11 (2008) (2) 105–112
Abstract: A novel photoprotective ingredient with anti-oxidant and electrophilic scavenging properties was designed. A structure–activity relationship study was conducted in order to optimize its bioavailability, specifically its ability to reach deep layers of the skin that may be affected by ultraviolet radiation-induced oxidative stress. A particular characteristic of this compound is its ability to release taurine upon reaction with some reactive oxygen species. In situ taurine formation may contribute to photoprotection. Preliminary in vitro experiments provide some evidence for effective protection against UVA-induced oxidative stress. Scavenging of the electrophilic species 4-hydroxynonenal, a highly cytotoxic end product of membrane lipid peroxidation, seems to be 2-oxo-1,3-thiazolidine major photoprotective mechanism.
Keywords: antioxidant, electrophilic species scavenging, photoprotection, structure-activity relationship, taurine
Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands 相似文献
Abstract: A novel photoprotective ingredient with anti-oxidant and electrophilic scavenging properties was designed. A structure–activity relationship study was conducted in order to optimize its bioavailability, specifically its ability to reach deep layers of the skin that may be affected by ultraviolet radiation-induced oxidative stress. A particular characteristic of this compound is its ability to release taurine upon reaction with some reactive oxygen species. In situ taurine formation may contribute to photoprotection. Preliminary in vitro experiments provide some evidence for effective protection against UVA-induced oxidative stress. Scavenging of the electrophilic species 4-hydroxynonenal, a highly cytotoxic end product of membrane lipid peroxidation, seems to be 2-oxo-1,3-thiazolidine major photoprotective mechanism.
Keywords: antioxidant, electrophilic species scavenging, photoprotection, structure-activity relationship, taurine
Paper presented at the IFSCC Conference 2007, Amsterdam, The Netherlands 相似文献
988.
Tarek Alouane Hlne Rimbert Jrg Bormann Gisela A. Gonzlez-Montiel Sandra Loesgen Wilhelm Schfer Michael Freitag Thierry Langin Ludovic Bonhomme 《International journal of molecular sciences》2021,22(12)
Fusarium graminearum, the primary cause of Fusarium head blight (FHB) in small-grain cereals, demonstrates remarkably variable levels of aggressiveness in its host, producing different infection dynamics and contrasted symptom severity. While the secreted proteins, including effectors, are thought to be one of the essential components of aggressiveness, our knowledge of the intra-species genomic diversity of F. graminearum is still limited. In this work, we sequenced eight European F. graminearum strains of contrasting aggressiveness to characterize their respective genome structure, their gene content and to delineate their specificities. By combining the available sequences of 12 other F. graminearum strains, we outlined a reference pangenome that expands the repertoire of the known genes in the reference PH-1 genome by 32%, including nearly 21,000 non-redundant sequences and gathering a common base of 9250 conserved core-genes. More than 1000 genes with high non-synonymous mutation rates may be under diverse selection, especially regarding the trichothecene biosynthesis gene cluster. About 900 secreted protein clusters (SPCs) have been described. Mostly localized in the fast sub-genome of F. graminearum supposed to evolve rapidly to promote adaptation and rapid responses to the host’s infection, these SPCs gather a range of putative proteinaceous effectors systematically found in the core secretome, with the chloroplast and the plant nucleus as the main predicted targets in the host cell. This work describes new knowledge on the intra-species diversity in F. graminearum and emphasizes putative determinants of aggressiveness, providing a wealth of new candidate genes potentially involved in the Fusarium head blight disease. 相似文献
989.
Haifeng Xie Thierry J Chaussalet Peter H Millard 《IEEE transactions on information technology in biomedicine》2006,10(3):512-518
Understanding the pattern of length of stay in institutional long-term care has important practical implications in the management of long-term care. Furthermore, residents' attributes are believed to have significant effects on these patterns. In this paper, we present a model-based approach to extract, from a routinely gathered administrative social care dataset, high-level length-of-stay patterns of residents in long-term care. This approach extends previous work by the authors to incorporate residents' features. Two applications using data provided by a local authority in England are presented to demonstrate the potential use of this approach. 相似文献
990.
Polynomial chaos expansion for sensitivity analysis 总被引:3,自引:0,他引:3
In this paper, the computation of Sobol's sensitivity indices from the polynomial chaos expansion of a model output involving uncertain inputs is investigated. It is shown that when the model output is smooth with regards to the inputs, a spectral convergence of the computed sensitivity indices is achieved. However, even for smooth outputs the method is limited to a moderate number of inputs, say 10-20, as it becomes computationally too demanding to reach the convergence domain. Alternative methods (such as sampling strategies) are then more attractive. The method is also challenged when the output is non-smooth even when the number of inputs is limited. 相似文献