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171.
J. Fernandez De La Mora 《Chemical Engineering Communications》1996,151(1):101-124
Due to their finite inertia, particles carried in a gas follow trajectories that differ from fluid streamlines. They may thus be size-segregrated, though only with the modest resolving power allowed by the dependence of their trajectories on the fluid streamline Ψin which they are initially seeded. This limitation is greatly reduced in the present work via aerodynamic focusing, a phenomenon discovered by Israel and Friedlander and briefly reviewed here. McM urry and his colleagues have recently shown that passage through a succession of coaxial converging nozzles brings virtually into the axis of symmetry (Ψ= 0) all particles within a relatively wide size range. Considerable gains in instrument resolution may thus be achieved by inserting a series of focusing nozzles right upstream of an aerosol size spectrometer. This general principle is demonstrated here for the case of variable-pressure impactors, which are ideally suited for coupling to the focusing lenses. The resolution improvements found are impressive, particularly in the viscous and compressible regimes. 相似文献
172.
N. Alberto Ortiz S. Luis Madrigal H. Rodrigo Fernandez Rodney D. Cooke 《Journal of the science of food and agriculture》1980,31(5):510-514
A range of latex storage and air drying conditions were studied with regard to the proteolytic activity of the dried latex (‘crude papain’). The optimum drying temperature is between 50–55°C, activity losses on drying can be restricted to about 7% under these conditions. The activity of crude papain is the same if it is derived either from exuded latex or from that portion (about 20% of latex yield) which coagulates on the fruit surface on tapping. Latex storage at tropical ambient for 2–24 h prior to drying (with or without exposure to sunlight) causes maximum losses of about 20% in the proteolytic activity of the crude papain. Sodium chloride addition has an anti-coagulating effect on latex and accelerates the later stages of drying. Contrary to earlier reports, this causes a decreased activity in the product, which may be related to changes in latex pH. Addition of EDTA or sodium bisulphite, singly or in combination, protects the latex activity (increases of 20–25% relative to controls). 相似文献
173.
Wambacq P. Fernandez F.V. Gielen G. Sansen W. Rodriguez-Vazquez A. 《Solid-State Circuits, IEEE Journal of》1995,30(3):327-330
A symbolic analysis tool is presented that generates simplified symbolic expressions for the small-signal characteristics of large analog integrated circuits. The expressions are approximated while they are computed, so that only those terms are generated which remain in the final expression. This principle causes drastic savings in CPU time and memory, compared with previous symbolic analysis tools. In this way, the maximum size of circuits that can be analyzed, is largely increased. By taking into account a range for the value of a circuit parameter rather than one single number, the generated expressions are also more generally valid. Mismatch handling is explicitly taken into account in the algorithm. The capabilities of the new tool are illustrated with several experimental results 相似文献
174.
Traumatic cord lesions in the newborn infant] 总被引:1,自引:0,他引:1
G Enriquez C Aso J Lucaya S Creixell E Fernandez 《Canadian Metallurgical Quarterly》1976,19(1):179-186
175.
In a multilevel database architecture, authorization rules may be written at the conceptual level or at the external level. We analyze here the consistency of authorization rules written at these two levels. We assume that the conceptual level model is of the entity-relationship type and the external model is relational. The validation of access requests against authorization rules is also discussed. 相似文献
176.
177.
Vano E Gonzalez L Guibelalde E Aviles P Fernandez JM Prieto C Galvan C 《Radiation protection dosimetry》2005,117(1-3):190-194
A methodology for the evaluation of skin dose distribution and possible skin injuries on patients undergoing interventional procedures has been developed as part of the European DIMOND programme. Relevant dosimetric data from the procedures are recorded and other specific measurements for skin dose evaluation (slow films for therapy, radiochromic films, thermoluminescence dosemeters and optically stimulated luminescence dosemeters) have been carried out. For non-cardiac and for some cardiac procedures, dose-area product values of 200 and 300 Gy cm2 were proposed, respectively, as a trigger level for further detailed skin dose investigation and possible clinical follow-up. Results from a survey of 191 selected complex procedures are reported. Out of all the patients included in the trial, 16% received skin doses > or =1.5 Gy. No skin injuries were found in any of the patients followed. 相似文献
178.
Rego G Fernandez Fernandez A Gusarov A Brichard B Berghmans F Santos JL Salgado HM 《Applied optics》2005,44(29):6258-6263
We experimentally study the effect of ionizing radiation on the properties of long-period gratings fabricated in two pure-silica-core fibers with the arc-discharge technique. It is observed that the spectra of the gratings remain almost unchanged after being subjected to doses in excess of 0.5 MGy. The results also show that the gratings' temperature and strain sensitivities are not affected by gamma radiation. 相似文献
179.
180.
S. Luis Madrigal N. Alberto Ortiz Rodney D. Cooke H. Rodrigo Fernandez 《Journal of the science of food and agriculture》1980,31(3):279-285
The yields of fresh papaya latex, dry latex (crude papain) and proteolytic activity were studied with respect to fruit age (1.5–3 months); sex of the tree (those which produce fruit: female and hermaphrodite); time (5:30 a.m.-2:00 p.m.) of latex collection; pattern and frequency of fruit incisions. The yields from 250 randomly selected trees (750 fruits) were investigated under these different conditions. Yields of fresh latex are frequently unreliable guides to yields of proteolytic activity. In contrast to the literature recommendations, the yields of crude papain from female and hermaphrodite trees and during different periods of the day were similar. The proteolytic activity differs significantly with time of collection only with hermaphrodite trees. The proteolytic activity of hermaphrodite crude papain is usually less than that from females (under some conditions only 60% of that from females). Yields of crude papain were higher in older fruits (2.5–3 months) from both sexes. The proteolytic activity of the crude papain was highest in the younger fruits (1.5–2 months) from female trees (30% higher than from older fruits); these activity differences with age were not significant with hermaphrodite trees. No significant differences in crude papain yields were encountered using three or six incisions per fruit at weekly intervals. The optimum procedure is to tap 2.5–3-month-old fruit of both sexes with three incisions between dawn and the start of rains in early afternoon, at about 4-day intervals. 相似文献