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71.
Acyl-CoA: alcohol transacylase activity was demonstrated in cell-free homogenates of developing jojoba seeds. The optimal
pH was 8.0–8.1. Under optimal conditions, wax formation had a nearly linear relationship with extract concentration; the time
course of wax formation was also linear up to 30 min.cis-11-Eicosenol was the most effective alcohol substrate whereas tetradecanol, octadecanol, dodecanol,cis-9-octadecanol, andcis-13-eicosenol gave progressively lower activities. Either saturated or unsaturated acyl-CoA with 18 or 20 C-atoms had similar
activity. The enzyme was fairly stable at 0 C, less stable at RT and labile above 30 C. Differential centrifugation showed
that the 12,000 × g fat pad was the most active in wax formation; to maximize the activity, a 12,000 × g supernatant appeared
to be necessary. This factor in the supermatant was thermolabile and nondialyzable. 相似文献
72.
73.
The activated sludge process might be used in the very near future to treat the waste liquors from small bisulfite mills in Canada, as a mean of controlling water pollution. These mills produce normally less than 300 t/d of pulp. It was found that the bio-sludge solids from such a process, when used to treat such waste liquor, contained approximately 38% protein, 47% carbohydrates, some vitamins and sufficient quantities of essential minerals. This bio-substance, a mixed-culture in nature, could be considered as a good source of single-cell protein. The nutritive value in terms of protein efficiency ratio of this substance was tested with rats; good results were obtained when the biomass was slightly supplemented with methionine. Described in this paper is a system used in our laboratory to produce this biomass in a sterile and dried form. The conversion of carbohydrates contained in waste pulping liquor to biomass was carried out in a 400-l, aerated, continuous-flow tank reactor. Under the operating conditions studied the sludge yield coefficient was 0.53 g of biomass/g of carbohydrates removed. A cash return study of selling biomass is also presented for two mills producing high- and low-yield pulps respectively. 相似文献
74.
Paillat T. Mas P. Moreau O. Touchard G. 《Dielectrics and Electrical Insulation, IEEE Transactions on》2003,10(1):7-14
The accumulated charge Q on a well insulated pressboard part being probably the most relevant parameter for flow electrification evolution inside transformers but clearly not measurable in situ, we compare in this paper this parameter with others possible to measure. The two most commonly used are oil parameters: ECT (electrostatic charging tendency) and, to a smaller extent, the continuous aging test for tan /spl delta/. Another is not so often used because of measurements difficulties, but was considered to be one of the most relevant: the leakage current. Thus in this paper we compare on two facilities (specially made for that) the accumulated charge Q to the ECT and leakage current. We find that, even if sometimes a correct correlation exists between these parameters, several cases show a bad correlation. Thus monitoring transformers by analyzing only ECT or leakage current seems to be hazardous. 相似文献
75.
Transmission electron microscopy (TEM) is a key technique in the structural characterization of carbon nanotubes. For device applications, carbon nanotubes are typically grown by chemical vapour deposition (CVD) on silicon substrates. However, TEM requires very thin samples, which are electron transparent. Therefore, for TEM analysis, CVD grown nanotubes are typically deposited on commercial TEM grids by post-processing. However, this procedure can damage the nanotubes, and it does not work reliably if the nanotube density is too low. The ability to do TEM directly on as-grown nanotubes on the silicon substrate would solve these problems. For this purpose, we have fabricated micromachined silicon TEM grids with narrow open slits on them. Since the nanotubes grown on these substrates are suspended freely over the open slits, the micromachined substrates form a natural TEM grid for direct imaging of CVD grown nanotubes. Furthermore, the background noise is significantly reduced during micro-Raman spectroscopy, resulting in a better signal-to-noise ratio. As a result, these micromachined Si substrates provide a low cost, mass producible, efficient, and reliable platform for direct TEM, SEM, AFM, and Raman characterization of as-grown nanotubes. These grids can be used for characterizing a wide range of other nanomaterials, including peapods, nanowires, and nanofibres. 相似文献
76.
77.
The analysis of lipids via HPLC with a charged aerosol detector 总被引:2,自引:0,他引:2
Because most lipid extracts are a mixture of saturated and unsaturated molecules, the most successful strategies for the quantitative
analysis of lipids have involved the use of so-called “mass” or universal detectors such as flame ionization detectors and
evaporative light scattering detectors. Recently a new type of HPLC “mass” detector, a charge aerosol detector (CAD), was
developed and is now commercially available. This detection method involves nebulizing the HPLC column effluent, evaporating
the solvents charging the aerosol particles, and measuring the current from the charged aerosol flux. In the present study,
the CAD was evaluated with several normal phase and reverse phase HPLC methods commonly used for the quantitative analysis
of lipid classes and lipid molecular species. The CAD detected common lipids such as triacylglycerols, diacylglycerols, glycolipids,
phospholipids, and sterols. Lower molecular weight lipids such as free FA had smaller peak areas (50–80% lower). FAME were
not detected by the CAD, probably because they were completely evaporated and did not form aerosol particles. The minimum
limits of detection of the CAD with lipids varied with different mobile phase solvents. Using solvent systems that were predominantly
hexane, the minimum limits of detection of triacylglycerols, cholesterol esters, and free sterols were about 1 ng per injection
and the mass-to-peak area ratio was nearly linear from the range of about 1 ng to about 20 mg per injection. Three other solvents
commonly used for HPLC lipid analysis (methanol, isopropanol, and acetonitrile) caused higher levels of background noise and
higher minimum limits of detection. These experiments indicate that the CAD has the potential to become a valuable tool for
the quantitative HPLC analysis of lipids. Long-term studies are needed to evaluate full instrument performance. 相似文献
78.
Moreau O. Michel R. Chevalier T. Meunier G. Joan M. Delcroix J.B. 《IEEE transactions on magnetics》2005,41(5):1364-1367
High frequency electrical machine modeling based on lumped parameter equivalent circuit requires that eddy currents effects be taken into account for R and L coefficient derivation. Substituting hysteretic materials (complex permeability) to conductive materials makes it possible to accurately approximate proximity losses and shielding effect while considering realistic meshes for finite element methods computation. Three-dimensional magnetodynamic simulations of transformer test-cases using anisotropic complex permeability for magnetic core and windings have shown a good agreement with the standard model results. 相似文献
79.
A method for measuring birefringence by use of thermal-light polarization-sensitive optical coherence tomography is presented. The use of thermal light brings to polarization-sensitive optical coherence tomography a resolution in the micrometer range in three dimensions. The instrument is based on a Linnik interference microscope and makes use of achromatic quarter-wave plates. A mathematical representation of the instrument is presented here, and the detection scheme is described, together with a discussion of the validity domain of the equations used to evaluate the birefringence in the presence of white-light illumination. 相似文献
80.
J. Zghal K. Moreau N. Moës D. Leguillon C. Stolz 《International Journal of Fracture》2018,211(1-2):253-280
The failure of quasi-brittle specimen weakened by sharp or blunted notches and cavities is analyzed under quasi-static loading. The load at failure is obtained with the Thick Level Set (TLS) damage modeling. In this model, the damage gradient is bounded implying that the minimal distance between a point where damage 0 (sound material) to 1 (fully damaged) is an imposed characteristic length in the model. This length plays an important role on the damage evolution and on the failure load. The paper shows that the TLS predictions are relevant. A comparison with the coupled criterion (CC) of Leguillon (2002) is given. A good agreement is obtained for cavities and V-notches provided that the characteristic length of Irwin is small compared to the notch depth (condition for the applicability of the CC criterion). A comparison with failure loads obtained experimentally is also given. In the numerical simulations, uniform stresses are imposed at infinity using a new finite element mapping technique (Cloirec 2005). 相似文献