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The interactions of the antihistaminic drug chlorpheniramine maleate (CPM) with the negatively charged polyelectrolytes poly(sodium 4-styrenesulfonate) (PSS) and poly(acrylic acid) (PAA) are studied by the washing method of the diafiltration technique at conditions simulating those of the small intestine such as pH 7.5 and 0.13 M NaCl. The results are compared with those already reported involving other pharmacologically important polyelectrolytes such as alginic acid (ALG), carboxymethylcellulose (CMC), and κ- and ι-carrageenan (κ- and ι-CAR). As in the case of ALG, CMC, and CAR, interactions of CPM with PAA appear to be electrostatic and are cleaved in the presence of 0.13 M NaCl. On the contrary, apart from electrostatic interactions, additional interactions are found with PSS and residual interactions are kept in the presence of 0.13 M NaCl, a fact that may be attributed to π-π interactions and hydrophobic forces. The effect of the addition of 4 M urea, branched poly(ethyleneimine) (BPEI), and poly(vinylpyrrolidone) (PVP) is also studied. The addition of urea 4 M or 0.001 M BPEI produces a decrease on the amounts of counterions bound to PSS at infinite elution, while the addition of PVP does not produce any change on the diafiltration profiles. 相似文献
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R Marana GF Catalano P Caruana F Margutti L Muzii S Mancuso 《Canadian Metallurgical Quarterly》1997,12(9):1935-1938
The efficacy of an oxidized regenerated cellulose barrier (Interceed) in reducing postoperative adhesion formation and improving reproductive outcome after ovarian surgery was evaluated in a prospective randomized trial. Twenty-nine New Zealand White female rabbits were submitted to a mid-line laparotomy and a standardized surgical incision was made on both ovaries. At random, one ovary was entirely wrapped in a sheet of Interceed, whereas the contralateral ovary was left uncovered. Four weeks following surgery, the rabbits were mated with a male of proven fertility. Two weeks later, a second-look laparotomy was performed by a blinded observer who evaluated the incidence and score of adhesions, the number of corpora lutea in each ovary, the number of embryos in the ipsilateral uterine horn and also calculated the nidation index for each side. Adhesions were observed in 66% of Interceed-covered and in 97% of control ovaries (P < 0.0001). The adhesion score on the Interceed side was significantly lower than on the control side. The nidation index for the Interceed side was significantly higher than for the control side. The authors conclude that, in the rabbit model, Interceed significantly reduces the incidence and score of postoperative ovarian adhesions and significantly improves reproductive outcome. 相似文献
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GF Gualdi MG Ferriano E Casciani C Pirolli E Polettini 《Canadian Metallurgical Quarterly》1997,148(5-6):209-224
In this report we reviewed the role of Ultrasonography, Computed Tomography, Magnetic Resonance and 99Tc-Sestamibi Scintigraphy for the detection of abnormal parathyroid glands in patients with biochemical evidence of hyperparathyroidism. We also report our personal experience with CT and RM. 相似文献
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This study examines the links between antecedents and consequences of Gabonese teachers' (N= 152) work motivation. The theoretical underpinnings are based on the Motivational Model of Job Burnout (MMJB) which is grounded in Self-Determination Theory (SDT) and states that the more supervisors satisfy an employee's need for self-determination, competence, and relatedness, the more self-determined is the latter's work motivation. The level of self-determined motivation has an impact on job satisfaction, which in turn determines life satisfaction. Higher levels of self-determined motivation also buffer emotional exhaustion and psychological distress. The model was confirmed via structural equation modeling and provides support for the validity and generalizability of the MMJB and SDT. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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In this paper, we summarize our recent efforts to analyze transmission probabilities of extremely thin SiO2 gate oxides using microscopic models of Si[100]-SiO2-Si[100] heterojunctions. We predict energy-dependent tunneling masses and their influence on transmission coefficients, discuss tunneling probabilities and analyze effects arising from the violation of parallel momentum conservation. As an application of the present method, gate currents in short bulk MOSFETs are calculated, including elastic defect-assisted contributions. 相似文献
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Many-Body Terms in van der Waals Cohesion Energy of Nanotubes 总被引:2,自引:0,他引:2
We have developed a model for the calculation of van der Waals force for layered systems with axial symmetry. Our result can be applied to compute the cohesion of a carbon nanotube to a substrate, the cohesion between nanotubes, and between shells of multiwall nanotubes. We have obtained unusal power laws for the distance dependence of the many-body van der Waals potential. 相似文献