This work investigates emulsion templating to synthesize hexadecane oil/geopolymer composites. In a system with hexadecane as the internal (dispersed) phase and an alkali activated continuous phase without added surfactant, adding aluminosilicate clay particles does not increase resistance against creaming or coalescence, while adding a surfactant (L35 or CTAB) stabilizes the solid-liquid interface. Infrared studies and rheological studies of the associated geopolymerization determined that the presence of the organic phase or surfactant has no significant effect on the geopolymerization kinetics, as determined by the change in time of the Si-O-T IR stretching frequency and the rheological moduli involved during the process. The stabilization of the organic template is reminiscent of Pickering emulsion even though we employ a much greater amount of inorganic material for geopolymer formation. Although the addition of surfactant has a significant effect on the behavior of the paste, the percolation of the network remains unmodified, highlighting the fact that the phenomenon is not dependent on viscosity. Finally, rheological measurements were used to obtain the mass fractal dimension of the as-made gel network, which is able to differentiate the interfacial effect between surfactant molecules with a slightly denser interphase when a cationic surfactant is used. 相似文献
A model for vibrations of a beam with a slider is derived, analysed and numerically simulated. It describes a viscoelastic beam that is clamped at one end to a vibrating device, while the other end moves between two stops attached to a slider. The contact is described by the normal compliance or by the Signorini conditions. The existence of weak solutions is established using the theory of set-valued pseudomonotone operators. The model is discretized using fourth-order spatial discretization, the solutions are numerically simulated and their results presented. The dynamics of the vibrations are depicted and so are the noise characteristics of the system. 相似文献
The first stages of nickel electrodeposition on amorphous carbon and polycrystalline silver substrates have been studied under galvanostatic conditions. An island growth mode is observed on the two types of substrate. For equivalent conditions the cluster density is higher on silver substrates than on carbon substrates. Dissolution of some nickel clusters is observed a short time after the onset of electrolysis on carbon substrates. This is confirmed by the evolution of the current efficiency and the evolution of the metal surface cluster density as a function of the quantity of electricity. 相似文献
Comments on J. J. Magnavita's (see record 1993-42219-001) assertion that Freud's purported discovery of unconscious processes and psychic structures "laid the groundwork for the scientific investigation of emotional disorders and techniques for their amelioration." Freud fabricated an architectonic structure from hypothetical constructs that were developed over 150 yrs of psychophilosophical and clinical investigations of psychotherapy. The concepts popularized by Freud are often seen as increasingly antiquated or as impediments to a contemporary science of the mind. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
Intrinsic, thermal, and hygroscopic contributions to the in-plane residual stress in silicon nitride films on polyimide substrates are identified, based on iso-hygric thermal ramps and isothermal relative humidity jumps, combined with non-linear elastic modeling of the resulting dynamics of film curvature. This approach enables the thermal and hygroscopic properties of thin nitride films to be determined and provides useful input for material and process control. 相似文献
The Multicenter Anti-Atheroma Study (MAAS) is a 2 + 2-year, placebo-controlled trial to evaluate the effect of simvastatin, a 3-hydroxy-3-methylglutaryl coenzyme a (HMG-CoA) reductase inhibitor, on progression and regression of coronary atherosclerosis in patients with established coronary artery disease. This paper describes the aims, methodology, and baseline data. Patients with at least two coronary segments visibly involved with atherosclerosis, in whom an angiogram was carried out according to the standards required for quantitative analysis, were selected provided that the serum total cholesterol was between 5.5 and 8.0 mmol/L and fasting triglycerides were lower than 4 mmol/L. Between march 1988 and October 1989, 383 eligible patients of both sexes aged 30-67 years were randomized in 11 European clinics. Patients received either 20 mg oral simvastatin or placebo daily for 2 years in addition to dietary counseling. The primary outcome measures are the change in the mean absolute width and in the mean of the minimal width of segments analyzed quantitatively by coronary angiography performed before and after 2 and 4 years of trial medication. To this end, at least 5 coronary artery segments are analyzed in each angiogram using matched view. The 2-year analysis was completed on 89% of eligible patients in February 1992. The trial was initially designed with a 2-year treatment period. To allow for the possibility to extend this, the decision was taken to keep all patients on the original medication allocation until all 2-year angiograms had been analyzed. Based on a predefined decision rule, an independent committee then recommended extension of treatment with another 2 years, to be concluded by a third angiogram. Of the patients enrolled initially, 81% continued. Four-year follow-up will be completed late 1993 and final results are expected mid 1994. 相似文献
In this perfusion magnetic resonance imaging study, the performances of different pseudo-continuous arterial spin labeling (PCASL) sequences were compared: two-dimensional (2D) single-shot readout with simultaneous multislice (SMS), 2D single-shot echo-planar imaging (EPI) and multishot three-dimensional (3D) gradient and spin echo (GRASE) sequences combined with a background-suppression (BS) module.
Materials and methods
Whole-brain PCASL images were acquired from seven healthy volunteers. The performance of each protocol was evaluated by extracting regional cerebral blood flow (rCBF) measures using an inline morphometric segmentation prototype. Image data postprocessing and subsequent statistical analyses enabled comparisons at the regional and sub-regional levels.
Results
The main findings were as follows: (i) Mean global CBF obtained across methods was were highly correlated, and these correlations were significantly higher among the same readout sequences. (ii) Temporal signal-to-noise ratio and gray-matter-to-white-matter CBF ratio were found to be equivalent for all 2D variants but lower than those of 3D-GRASE.
Discussion
Our study demonstrates that the accelerated SMS readout can provide increased acquisition efficiency and/or a higher temporal resolution than conventional 2D and 3D readout sequences. Among all of the methods, 3D-GRASE showed the lowest variability in CBF measurements and thus highest robustness against noise.
The neuromuscular blocker advisory system (NMBAS) is a computer program developed to provide advisory guidance to anesthesiologists on the timing and dose of rocuronium to paralyze patients during surgery. It is believed that the use of such a system will administer the minimally effective amount of drug, maintaining the patient in a state of paralysis that is useful for surgery yet easily reversible. This will improve patient safety and result in more efficient care. In this paper we present the NMBAS, its basic methodology, and its development though a pilot study. Novel methods of handling neuromuscular response data are presented, including relaxation measurement and the enhanced-train-of-four sensing modality. New methods of handling nonlinearities at the neuromuscular junction to allow application of adaptive control techniques are presented. A novel form of modelling combining model swapping and RLSE adaptation to accommodate the patient variation seen with NMB drugs is introduced. A pilot study testing the NMBAS was undergone to prepare the NMBAS for application in a full clinical trial, in which patients undergoing prostate brachytherapy surgeries using rocuronium for intubation were admitted. 相似文献