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1.
A new indirect method for measuring the level of beta-methyl-gamma-octalactone precursors in oak wood by GC-MS is described. This level is calculated from the difference between the amount of free beta-methyl-gamma-octalactone and the amount formed after hydrolysis and lactonization. It is compared to the level of a precursor of cis-beta-methyl-gamma-octalactone, a 6'-O-gallate derivative of (3S,4S)-4-[3-beta-glucopyranosyloxy-3-methyloctanoic acid, determined directly by HPLC. These two methods are applied to 12 powdered samples of Sessile oak wood and the results show that the 6'-O-gallate derivative of (3S,4S)-4-beta-D-glucopyranosyloxy-3-methyloctanoic acid is by far the most abundant precursor of beta-methyl-gamma-octalactone in this wood. 相似文献
2.
C. Puech 《Optics Communications》1973,7(2):135-138
A method which permits duplication of thin film optical components is described. A metallic master fabricated from an original recording on photoresist, is used to make numerous copies by embossing a sheet of a non-expensive plastic material. Some examples are given to illustrate the method. 相似文献
3.
We present the first measurements of the thermal conductivity of spin-polarized normal liquid 3He. Using the rapid melting technique to produce nuclear polarizations up to 0.7, and a vibrating wire both as a heater and a thermometer, we show that, unlike the viscosity, the conductivity increases much less than predicted for s-wave scattering. We suggest that this might be due to a small probability for head-on collisions between quasiparticles. 相似文献
4.
Optical parametric oscillation in periodically poled lithium niobate driven by a diode-pumped Q-switched erbium fiber laser 总被引:2,自引:0,他引:2
Britton PE Taverner D Puech K Richardson DJ Smith PG Ross GW Hanna DC 《Optics letters》1998,23(8):582-584
We describe what is to our knowledge the first nanosecond periodically poled lithium niobate (PPLN) optical parametric oscillator (OPO) driven by a fiber laser. The source was frequency doubled by a PPLN sample before pumping a second, 20-mm-long, PPLN crystal. The OPO threshold was <10muJ, with pump depletions of as much as 45% and a tunable signal range of 945-1450 nm (1690-4450-nm idler range). We demonstrated 130-nm signal tuning by varying the pump wavelength and doubling crystal's temperature. Also, we achieved 15-nm tuning with all crystals at a constant temperature. The results demonstrate the potential of the fiber laser:PPLN combination for practical, versatile, and tunable sources. 相似文献
5.
L. Richeboeuf S. Pasquiers F. Doussiet M. Legentil C. Postel V. Puech 《Applied physics. B, Lasers and optics》1999,68(1):45-53
3 , has been performed in Ne/SF6/H2 and Ne/SF6/C2H6 mixtures. Parameters involved have been the storage line capacitance and the circuit inductance, the capacitors charging
voltage, the RH-molecule type and partial pressure, and the X-ray dose for the preionization. High laser performance has been
achieved with C2H6: an output energy up to 3 J corresponding to a specific energy of 9.6 J/l at an efficiency of 4.7%, which strengthens the
advantage of the photo-triggering technique to energize high-power HF lasers. However the optimum performance achieved with
H2, 5.75 J/l and 3.5%, are lower. It is shown, through a time-resolved study of the electrical discharge and spatial dynamics
correlated to laser power and energy measurements, that discharge instabilities are responsible for the poor laser performance
of the mixture with H2. These instabilities, which lead to arc development, are characteristics of the discharge in Ne/SF6. It is demonstrated for the first time that addition of a heavy hydrocarbon, such as C2H6, to that mixture induces the discharge stabilization so that the laser emission arises in a homogeneous active medium. This
effect allows us to achieve better laser performance than with H2.
Received: 17 March 1998/Revised version: 13 July 1998 相似文献
6.
We characterize trees with equal domination and independent domination numbers in terms of the sets of vertices of the tree which are contained in all its minimum dominating and minimum independent dominating sets. © 2000 John Wiley & Sons, Inc. J Graph Theory 34: 277–292, 2000 相似文献
7.
Yu Wang Pascal Puech Iann Gerber Alain Pnicaud 《Journal of Raman spectroscopy : JRS》2014,45(3):219-223
Graphite intercalation compounds, due to charge transfer between layers of graphite and intercalants, have a strongly shifted Fermi level. Potassium is known to give its electron leading to a large charge transfer fc close to for stage 1 (KC8) and for stage 2 (KC24). The question is more subtle in stage 3 (KC36) for which the graphene layers are not equivalent. For stage 3, two Raman G bands are clearly visible, corresponding to the interior layer and the boundary layers, respectively. By varying the excitation energy from UV to infrared, we observe that the intensity of the boundary layers G band versus that of the interior layer is maximum at 2.5 eV, leading to a sharp resonance profile at room temperature. Using first‐principle calculation, we associate this transition to π → π∗ of the bounding layers. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
The importance of pre-ionisation for the non-chain discharge-pumped HF laser is studied through experiments on an X-ray photo-triggered
laser using mixtures of Ne, SF6, and ethane. The discharge dynamic in Ne/SF6 mixtures or pure SF6, as well as the stabilisation effect induced by C2H6 and consequences for the laser performance, are investigated for pre-ionisation electron density values, neo, ranging from 106 cm-3 up to 109 cm-3, as well as for the so-called discharge self-breakdown mode. Without ethane, the minimum neo value which is needed to complete 100% homogeneous charge deposition in the plasma is a very sharply increasing function
of the SF6 pressure. This hinders performance optimisation when the molecule used to react with F-atoms, for instance H2, has no effect on the discharge dynamic. The minimum ethane partial pressure that is needed to stabilise the discharge depends
on neo, the pumping pulse duration, the deposited electric charge, and the SF6 pressure. Discharges in Ne/SF6 can be much more efficiently stabilised by addition of a small amount of ethane than by an increase of neo. A pre-ionisation density as low as 106 cm-3 is sufficient to achieve the maximum laser energy value, but total suppression of the pre-ionisation has a detrimental effect
on the active medium homogeneity.
Received: 30 May 2000 / Revised version: 9 October 2000 / Published online: 9 February 2001 相似文献
9.
14C-labelledtracers were incorporated into botryococcenes, triterpenoid hydrocarbons produced by a variety of the unicellular alga . Data obtained with L-leucine might support for the biosynthesis the possibility of a non-mevalonoid pathway. 相似文献
10.
Puech PH Feracci H Brochard-Wyart F 《Langmuir : the ACS journal of surfaces and colloids》2004,20(22):9763-9768
Here, we present a study of adhesion between cadherin fragments using giant unilamellar vesicles and supported bilayers. These objects are partially made of nickel chelating lipids and are subsequently decorated with proteins bearing a 6His tag. Initially, we observed their fixation and correct orientation by using a fluorescent protein, the green fluorescent protein (GFP)-6His. The adhesive behavior of E-cadherin functionalized giant vesicles and supported bilayers was studied as a function of the calcium concentration and of the protein functionality by reflection interference microscopy. We show that such a system retains specific cadherin-mediated adhesion and could be used to study the statics and dynamics of adhesive plaques as well as to gain insight into the fundamental mechanisms of cellular adhesion at the mesoscopic scale. 相似文献