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121.
Thierry Durand Valérie Bultel-Poncé Alexandre Guy Susanne Berger Martin J. Mueller Jean-Marie Galano 《Lipids》2009,44(10):875-888
In animals and plants, fatty acids with at least three double bonds can be oxidized to prostaglandin-like compounds via enzymatic
and non-enzymatic pathways. The most common fatty acid precursor in mammals is arachidonic acid (C20:4) (AA) which can be
converted through the cyclooxygenase pathway to a series of prostaglandins (PG). Non-enzymatic cyclization of arachidonate
yields a series of isoprostanes (IsoP) which comprises all PG (minor compounds) as well as PG isomers that cannot be formed
enzymatically. In contrast, in plants, α-linolenic acid (C18:3) (ALA) is the most common substrate for the allene oxide synthase
pathway leading to the jasmonate (JA) family of lipid mediators. Non-enzymatic oxidation of linolenate leads to a series of
C18-IsoPs termed dinor IsoP or phytoprostanes (PP). PP structurally resemble JA but cannot be formed enzymatically. We will
give an overview of the biological activity of the different classes of PP and also discuss their analytical applications
and the strategies developed so far for the total synthesis of PP, depending on the synthetic approaches according to the
targets and which key steps serve to access the natural products. 相似文献
122.
123.
124.
Thierry A. Blanchet 《摩擦学汇刊》2013,56(4):821-828
A rule-of-mixtures model is developed for the time-dependent wear and friction behavior of polymer matrix materials containing particulate filler inclusions, based upon the specific wear rates of filler and matrix materials. The model accounts for the accumulation of wear-resistant filler particles within the near-surface region of the composite as sliding proceeds. Account is also made for preferential support of the normal load by filler particles at the sliding surface. Though particle/matrix interfacial shear stress and particle aspect ratio do affect initial transient behavior, wear rate, and friction are independent of preferential load support under steady-state conditions. The model indicates that steady-state composite wear rate can be most affected by the specific wear resistance of the filler particles, as well as the volume fraction filling of particles into the polymer matrix. 相似文献
125.
Eddy Collin Laure Filleau Thierry Fournier Yuriy M. Bunkov Henri Godfrin 《Journal of Low Temperature Physics》2008,150(5-6):739-790
Nowadays microfabrication techniques originating from micro-electro nics enable to create mechanical objects of micron-size.
The field of Micro-Electro-Mechanical devices (MEMs) is continuously expanding, with an amazingly broad range of applications
at room temperature.
Vibrating objects (torsional oscillators, vibrating wires) widely used at low temperatures to study quantum fluids, can be
replaced advantageously by Silicon MEMs. In this letter we report on the study of Silicon vibrating wire devices. A goal-post
structure covered with a metal layer is driven at resonance by the Laplace force acting on a current in a magnetic field,
while the induced voltage arising from the cut magnetic flux allows to detect the motion. The characteristics of the resonance
have been studied from 10 mK to 30 K, in vacuum and in 4He gas. In this article, we focus on the results obtained above 1.5 K, in vacuum and gas, and introduce some features observed
at lower temperatures.
The resonant properties can be quantitatively understood by means of simple models, from the linear regime to a highly non-linear
response at strong drives. We demonstrate that the non-linearity is mostly due to the geometry of the vibrators. We also show
that in our device the friction mechanisms originate in the metallic layers, and can be fully characterized. The interaction
with 4He gas is fit to theory without adjustable parameters.
相似文献
126.
127.
Today, the mobile phone industry witnesses important changes, shifting from a value chain to a burgeoning business ecosystem. This paper deals with the relationships that are at the very core of mobile OS ecosystems for IMTs (smartphones and PDA): Microsoft-OS, Symbian-OS, Palm-OS and RIM-OS over the period 1998–2006. Our study confirms that an ecosystem’s borders are unclear. More than half of our sample’ relationships are shared by at least two different ecosystems. The ecosystems we studied do not differ in terms of exclusive relationship which suggests that coopetitive strategies are particularly relevant in mobile platforms war. 相似文献
128.
Kate Dunning Adeline Martz Francisco Andrs Peralta Federico Cevoli Eric Bou-Grabot Vincent Compan Fanny Gautherat Patrick Wolf Thierry Chataigneau Thomas Grutter 《International journal of molecular sciences》2021,22(12)
P2X7 receptors (P2X7) are cationic channels involved in many diseases. Following their activation by extracellular ATP, distinct signaling pathways are triggered, which lead to various physiological responses such as the secretion of pro-inflammatory cytokines or the modulation of cell death. P2X7 also exhibit unique behaviors, such as “macropore” formation, which corresponds to enhanced large molecule cell membrane permeability and current facilitation, which is caused by prolonged activation. These two phenomena have often been confounded but, thus far, no clear mechanisms have been resolved. Here, by combining different approaches including whole-cell and single-channel recordings, pharmacological and biochemical assays, CRISPR/Cas9 technology and cell imaging, we provide evidence that current facilitation and macropore formation involve functional complexes comprised of P2X7 and TMEM16, a family of Ca2+-activated ion channel/scramblases. We found that current facilitation results in an increase of functional complex-embedded P2X7 open probability, a result that is recapitulated by plasma membrane cholesterol depletion. We further show that macropore formation entails two distinct large molecule permeation components, one of which requires functional complexes featuring TMEM16F subtype, the other likely being direct permeation through the P2X7 pore itself. Such functional complexes can be considered to represent a regulatory hub that may orchestrate distinct P2X7 functionalities. 相似文献
129.
Patrice Pellerin Thierry Doco Geoffrey R. Scollary 《International Journal of Food Science & Technology》2013,48(12):2676-2682
The influence of wine polymers on the spontaneous precipitation of calcium tartrate in a model wine system has been examined. Rhamnogalacturonan‐I was identified as the most effective inhibitor (precipitation induction time of 180 min compared with 7 min for the standard model). It is argued that this is a consequence of rhamnogalacturonan‐I's ability to participate in the ‘egg‐box’ type sequestration of calcium ions. The more structurally complex rhamnogalacturonan‐II had only a minor influence on the induction time (22 min). Arabinogalactan proteins and mannoproteins also have little influence with induction times ranging from 12 to 15 min. An ultra‐filtration study of four Chardonnay wines, prepared with and without the use of pectolytic enzymes, was performed in a search for conditions that might maximise the concentration of rhamnogalacturonan‐I. However, rhamnogalacturonan‐I could not be identified in any of the four wines. Implications of these observations, specifically the need to understand the inhibition exerted by specific uronic acids, for winemaking and calcium tartrate precipitation are discussed. 相似文献
130.
Fourier transform absorption infrared spectroscopy is a powerful and versatile tool used to determine the molecular structure of biomolecules. This technique is now widely used in biochemistry to study the conformation of biopolymers in aqueous solutions and complex systems. However, its enormous potential in the study of food biopolymers has yet to be reached. The aim of this paper is principally to provide information on biopolymers using Fourier transform infrared spectroscopy. β-Lactoglobulin (β-Lg), the major whey protein in the milk of ruminants, is chosen as a model. Emphasis will be put on the different structure levels of proteins in an aqueous solution, the protein–protein interactions, and the protein interactions with small host-molecules such as phospholipids. 相似文献