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Cypriano G da Trindade Neto Ana LP Fernandes Ana IB Santos Waldenice A Morais Marcos VM Navarro Tereza NC Dantas Mrcia R Pereira Jos LC Fonseca 《Polymer International》2005,54(4):659-666
Complexation of chitosan in aqueous solutions by low molecular weight electrolytes is one of the simplest methods for the preparation of aqueous chitosan dispersions. In this work, the influence of storage time, sulfate concentration, method of preparation and surfactant content on some properties of the resultant chitosan dispersions (turbidity, viscosity and zeta potential) was analyzed. Turbidimetry was adequate to monitor the formation of particles, while viscometry was suitable to monitor changes in the dispersing phase. An analysis of the properties of these systems, mainly in terms of particle–particle and macromolecule–macromolecule interactions was carried out. Copyright © 2004 Society of Chemical Industry 相似文献
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MC Bueno Jayme Gallani RC Rodrigues Colombo E de Araújo Cintra S Brunelli Rigacci 《Canadian Metallurgical Quarterly》1996,4(2):179-199
The overall purpose of this study was to explore nurses' feelings about the applicability and adequacy of a pilot model of nursing assessment (PMNA) developed for coronary care units (CCU) in order to obtain data that could help in establishing a definitive model. The evaluation, performed by 11 CCU nurses, showed that they considered the development and implementation of PMNA as valuable, and that its design was adequate for interviewing cardiac patients. These results will be employed in the elaboration of a definitive model of nursing assessment. 相似文献
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A novel directive and nondispersive antenna is presented: the ultrawideband (UWB) leaky lens. It is based on the broad band Cherenkov radiation occurring at a slot printed between different infinite homogeneous dielectrics. The first part of the paper presents the antenna concept and the UWB design. The issues that are specifically addressed include the impedance matching, the radiation pattern and the phase purity. Subsequently the hardware demonstrator and the results of the measurement campaign are shown. The results fully validate the antenna concept. The antenna presents decade bandwidth impedance matching, directive and frequency independent patterns in the H-plane over two octaves, negligible cross-polarization levels, weak amplitude dispersivity and, according to the authors, the most stable phase center for a directive antenna over an ultra wide frequency range. 相似文献
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Lima A.M.N. Deep G.S. Neto J.S.R. Freire R.C.S. Lobo P.C. 《IEEE transactions on instrumentation and measurement》1994,43(2):133-138
An identification procedure to estimate the parameters of a thermoresistive solar radiation sensor is presented. The proposed technique employs only electrical excitation for the sensor. The estimation algorithm is recursive and is applied to the sensor model derived from the thermodynamic equilibrium differential equations. The simulation and the experimental results demonstrate the validity of the proposed approach 相似文献
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The authors present experimental results which indicate that a Dy 3+-doped Ga:La:S glass fibre amplifier may be operated efficiently at 1.3 μm with an optimum device length significantly shorter than a comparable Pr3+-doped glass fibre amplifier. Moreover, the efficiency exceeds that obtained from the Pr3+-doped ZBLAN devices currently available 相似文献
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