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11.
Dynamics of self-assembled chaining in magnetorheological fluids 总被引:1,自引:0,他引:1
Climent E Maxey MR Karniadakis GE 《Langmuir : the ACS journal of surfaces and colloids》2004,20(2):507-513
The aggregation dynamics of paramagnetic spherical particles embedded in a viscous fluid is investigated via numerical simulations using a fully coupled three-dimensional model. Particles experience simultaneously Brownian motion, dipolar magnetic attraction, and multibody hydrodynamic interactions. When the dipole strength characterizing the ratio of magnetic attraction to random diffusion exceeds a critical value, particles join together forming supraparticle structures. As time evolves, particle/chain and chain/ chain interactions lead to a continuous increase of the cluster size. The mean length of particle chains has a power-law dependence with respect to time, as predicted by the theory of diffusion-limited aggregation. Both the exponent and the characteristic time scale agree very well with the experimental results of Promislow et al. 相似文献
12.
The Michael addition of nitromethane to 3-buten-2-one has been carried out in the absence of solvent, using potassium fluoride supported on Al2O3, ZnO, SnO2, sepiolite, AlPO4, AlPO4–Al2O3 and AlPO4–ZnO catalysts. We found that KF/ZnO easily performed the Michael addition and thus, ZnO is a better support for the basic reagent than Al2O3. Besides, the Michael addition was not successful with AlPO4 or AlPO4-metal oxide acidic supports.
3--2- , , Al2O3, ZnO, SnO2, , AlPO4, AlPO4–Al2O3 AlPO4–ZnO. , KF/ZnO .. ZnO, , , Al2O3. , , AlPO4 AlPO4- .相似文献
13.
M. S. Climent J. M. Marinas J. V. Sinisterra 《Reaction Kinetics and Catalysis Letters》1989,38(1):13-19
Several new supported K2Cr2O7 reagents are used in the oxidation of secondary alcohols. The influence of the number of active sites and the nature of solid support on the yield is discussed. The influence of the structure of alcohol on the yield of ketone is analyzed.
K2Cr2O7 . . .相似文献
14.
A spectrophotometric flow-injection method for the determination of silicate based on the formation of an ion pair between molybdosilicic acid and Rhodamine B is proposed. It allows silicate to be determined over the concentration range 0.17–2.0 mg 1?1 at a sampling rate of 40 h?1, is reasonably precise and is highly tolerant to ions that commonly occur in waters. It has been applied with satisfactory results to the determination of silicate in various types of water. 相似文献
15.
Estela M. Alvarez Patricia H. Risso Carlos A. Gatti Martín S. Armesto Mariano Burgos Verónica M. Relling 《Colloid and polymer science》2006,284(9):1016-1023
Colloidal casein aggregates (CCA) prepared from soluble whole bovine caseinates in the presence of Ca2+ and phosphate (Pi) ions by addition of different citrate (Cit) concentrations showed different mineral and proteic composition. Citrate concentration conditions the Ca and Pi concentrations incorporated into CCA, probably due to the complexing effect of this anion on calcium. A significant change in the incorporated Ca/Pi ratio at 8 mM citrate could very likely be associated to changes in CCA net charge. The incorporation of individual caseins to the colloidal particles obtained, as well as their average size and size distribution, depended also on the Cit concentration used [Cit]P. αS- and β-caseins assembled in the CCA structure sharply decreased at a [Cit]P higher than 15 mM, i.e., at a low Ca2+ concentration in the aggregates, showing that the presence of this cation is necessary for the incorporation of these caseins. An inverse relationship between the aggregation step rate in CCA enzymic coagulation and their average size was observed. The aggregation rate vs the average size curve obtained at [Cit]P 8 mM clearly differed from the curves obtained at 10 and 12 mM, respectively, a fact probably related to a change in the CCA net charge. This behavior showed the effect of citrate concentration on CCA functional properties. 相似文献
16.
It is an open question whether there is a strange attractor for the Henon mapping. We show that for certain maps close to
the Henon map there are strange attractors. 相似文献
17.
Estela de Pieri Troiani Edenir Rodrigues Pereira‐Filho Ronaldo Censi Faria 《Electroanalysis》2013,25(8):1988-1994
A simple and sensitive method for simultaneously measuring dopamine (DA), ascorbic acid (AA), and uric acid (UA) using a poly(1‐aminoanthracene) and carbon nanotubes nanocomposite electrode is presented. The experimental parameters for composite film synthesis as well as the variables related to simultaneous determination of DA, AA, and UA were optimized at the same time using fractional factorial and Doehlert designs. The use of carbon nanotubes and poly(1‐aminoanthracene) in association with a cathodic pretreatment led to three well‐defined oxidation peaks at potentials around ?0.039, 0.180 and 0.351 V (vs. Ag/AgCl) for AA, DA, and UA, respectively. Using differential pulse voltammetry, calibration curves for AA, DA, and UA were obtained over the range of 0.16–3.12×10?3 mol L?1, 3.54–136×10?6 mol L?1, and 0.76–2.92×10?3 mol L?1, with detection limits of 3.95×10?5 mol L?1, 2.90×10?7 mol L?1, and 4.22×10?5 mol L?1, respectively. The proposed method was successfully applied to determine DA, AA, and UA in biological samples with good results. 相似文献
18.
Sergio Català‐Clariana Fernando Benavente Estela Giménez José Barbosa Victoria Sanz‐Nebot 《Electrophoresis》2013,34(13):1886-1894
Biologically active peptides derived from complex bovine milk protein hydrolysates are of particular interest in food science and nutrition because they have been shown to play different physiological roles, providing benefits in human health. In this study, we used CE‐TOF‐MS for separation and identification of bioactive peptides in three hypoallergenic infant milk formulas. An appropriate sample cleanup using a citrate buffer with DTT and urea followed by SPE with Sep‐Pack® C18 and StrataXTM cartridges allowed the detection of a large number of low molecular mass bioactive peptides. This preliminary identification was solely based on the measured experimental monoisotopic molecular mass values (Mexp). Later, we evaluated the classical semiempirical relationships between electrophoretic mobility and charge‐to‐mass ratio (me vs. q/Mα, α = 1/2 for the classical polymer model) to describe their migration behavior. The assistance of migration prediction proved to be useful to improve reliability of the identification, avoiding misinterpretations and solving some identity conflicts. After revision, the identity of 24, 30, and 38 bioactive peptides was confirmed in each of the three infant milk formulas. A significant number of these peptides were reported as inhibitors of angiotensin‐converting enzyme, however, the presence of sequences with other biological activities such as antihypertensive, antithrombotic, hypocholesterolemic, immunomodulation, cytotoxicity, antioxidant, antimicrobial, antigenic, or opioid was also confirmed. 相似文献
19.
Josué Antonio Nescolarde‐Selva José Luis Usó-Doménech Miguel Lloret‐Climent 《Complexity》2015,21(2):47-65
The goal of this article is to build an abstract mathematical theory rather than a computational one of the process of transmission of ideology. The basis of much of the argument is Patten's Environment Theory that characterizes a system with its double environment (input or stimulus and output or response) and the existing interactions among them. Ideological processes are semiotic processes, and if in Patten's theory, the two environments are physical, in this theory ideological processes are physical and semiotic, as are stimulus and response. © 2014 Wiley Periodicals, Inc. Complexity 21: 47–65, 2015 相似文献
20.
Interactive music uses wearable sensors (i.e., gestural interfaces—GIs) and biometric datasets to reinvent traditional human–computer interaction and enhance music composition. In recent years, machine learning (ML) has been important for the artform. This is because ML helps process complex biometric datasets from GIs when predicting musical actions (termed performance gestures). ML allows musicians to create novel interactions with digital media. Wekinator is a popular ML software amongst artists, allowing users to train models through demonstration. It is built on the Waikato Environment for Knowledge Analysis (WEKA) framework, which is used to build supervised predictive models. Previous research has used biometric data from GIs to train specific ML models. However, previous research does not inform optimum ML model choice, within music, or compare model performance. Wekinator offers several ML models. Thus, we used Wekinator and the Myo armband GI and study three performance gestures for piano practice to solve this problem. Using these, we trained all models in Wekinator and investigated their accuracy, how gesture representation affects model accuracy and if optimisation can arise. Results show that neural networks are the strongest continuous classifiers, mapping behaviour differs amongst continuous models, optimisation can occur and gesture representation disparately affects model mapping behaviour; impacting music practice. 相似文献