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91.
We demonstrate the supramolecular bioconjugation of concanavalin A (Con A) protein with glycoenzyme horseradish peroxidase (HRP) inside single nanopores, fabricated in heavy ion tracked polymer membranes. Firstly, the HRP-enzyme was covalently immobilized on the inner wall of the pores using carbodiimide coupling chemistry. The immobilized HRP-enzyme molecules bear sugar (mannose) groups available for the binding of Con A protein. Secondly, the bioconjugation of Con A on the pore wall was achieved through its biospecific interactions with the mannose residues of the HRP enzyme. The immobilization of biomolecules inside the nanopore leads to the reduction of the available area for ionic transport, and this blocking effect can be exploited to tune the conductance and selectivity of the nanopore in aqueous solution. Both cylindrical and conical nanopores were used in the experiments. The possibility of obtaining two or more conductance states (output), dictated by the degree of nanopore blocking resulted from the different biomolecules in solution (input), as well as the current rectification properties obtained with the conical nanopore, could also allow implementing information processing at the nanometre scale. Model simulations based on the transport equations further verify the feasibility of the sensing procedure that involves concepts from supramolecular chemistry, molecular imprinting, recognition, and nanotechnology. 相似文献
92.
Degradation of an Azo Dye (Ponceau 4R) and Treatment of Wastewater from a Food Industry by Ozonation
Cristina Benincá Patricio Peralta-Zamora Célia Regina Granhen Tavares Luciana Igarashi-Mafra 《臭氧:科学与工程》2013,35(4):295-301
Experiments for degradation of the extensively marketed Ponceau 4R dye in aqueous solution and for oxidation of raw wastewater from a confectionary industry have been carried out by using ozone. All the experiments were performed in a cylindrical semi-batch reactor at approximately 20 oC for 7200 s. A mass flow rate of 1.158?×?10?6 kg s?1 of ozone was continuously fed in the reactor. The pH of the azo dye aqueous solution (distilled water + Ponceau 4R) was always kept at approximately 5.8, while in the case of the raw wastewater the same factor was changed from 4.7 to 9.4 in two different experimental runs. Absorbance measurements at 508 nm show that the investigated azo dye found in the azo dye aqueous solution was completely degraded after only 600 s. At this initial period a substantial fall of TOC (Total Organic Carbon) (up to 45%) was noticed, but the rate was exponentially decreased at longer reaction times up to a TOC removal no higher than 60%. The ozonation was also responsible for reducing the apparent color of the raw wastewater to almost 10% of its initial value at the optimum pH (9.4 ± 1.5). The effect of pH was important on apparent color, but it had absolutely no influence on the kinetics results of COD (Chemical Oxygen Demand), which were kept constant over the entire period of reaction. 相似文献
93.
L. M. Oliveira de Lima J. H. da Silva A. A. Ribeiro Patricio E. L. de Barros Neto A. A. Dantas Neto T. N. de Castro Dantas 《Petroleum Science and Technology》2013,31(9):994-1004
Abstract This study seeks to investigate the use of a surfactant derived from coconut oil in the recovery process of organic compounds from oily effluents. To evaluate its efficiency in oil removal and its optimal concentration for each oil/water ratio, experiments were carried out using water/oil emulsions (50, 100, 200, and 400 ppm of oil) and produced water (50 ppm) in a small-scale column. According to these experiments, it was verified that there is an optimum surfactant concentration for each emulsion, and for produced water the extraction efficiency reaches a maximum value (80%) at a surfactant concentration of 0.1 g/L?1. 相似文献
94.
Membrane gas absorption technology is a promising alternative for CO2 removal from post-combustion coal-fired flue gases. This study examines an alternative which consists in absorbing carbon dioxide by ammonia aqueous solution in a membrane contactor to improve the capture processes and to intensify the gas–liquid transfer. Absorption measurements through a membrane contactor have been made. The influence of the material nature constituting the membrane and operating parameters on the capture efficiency has been studied. The potentialities of dense skin membrane contactors are discussed with regard to both increased CO2 mass transfer performances and mitigation of ammonia volatilization. The results have shown that it is possible to capture CO2 from ammonia through a membrane with capture efficiency greater than 90 %. The membrane limits ammonia losses but does not eliminate it. The experimental results are used to calculate an intensification factor of 5, which represents the comparison between the membrane overall absorption rate to that of the column. 相似文献
95.
A rigorous modal theory is described for the study of the diffraction of electromagnetic plane waves by bigratings of hemispherical cavities hollowed in a plane surface of perfectly conducting material. The theoretical study is realized for any incidence and direction of polarization and our first numerical results concern only the simpler case of normal incidence. Under this condition the efficiency curvesepsilon_{pq} of the various real diffracted orders are studied. We find that the cavity depthR has an important influence on the shape of the curves. In particular, the 相似文献
96.
E Stefani M Ottolia F Noceti R Olcese M Wallner R Latorre L Toro 《Canadian Metallurgical Quarterly》1997,94(10):5427-5431
Large conductance calcium- and voltage-sensitive K+ (MaxiK) channels share properties of voltage- and ligand-gated ion channels. In voltage-gated channels, membrane depolarization promotes the displacement of charged residues contained in the voltage sensor (S4 region) inducing gating currents and pore opening. In MaxiK channels, both voltage and micromolar internal Ca2+ favor pore opening. We demonstrate the presence of voltage sensor rearrangements with voltage (gating currents) whose movement and associated pore opening is triggered by voltage and facilitated by micromolar internal Ca2+ concentration. In contrast to other voltage-gated channels, in MaxiK channels there is charge movement at potentials where the pore is open and the total charge per channel is 4-5 elementary charges. 相似文献
97.
The paper deals with soil probing by a set of emitterdetectors moving along a well. In a first step, the problem of retrieving permittivity and conductivity from the measured signals is analyzed in the framework of a simple but realistic one-dimensional model. An iterative optimization approach is adopted, making use of classical techniques of the theory of optimization. An objective function is defined, and its gradient is calculated with the help of an "adjoint field." Some results are given that show the ability of the method to reconstruct permittivity and conductivity profiles. 相似文献
98.
Patricio E. Ramírez-Correa F. Javier Rondan-Cataluña Jorge Arenas-Gaitán Jorge L. Alfaro-Perez 《Telematics and Informatics》2017,34(1):272-286
This study uses the DeLone and McLean model to determine the moderating impact of learning styles on the success of learning management systems from a student’s point of view. The main objectives of this research are: (1) to evaluate the Delone and McLean model of information system success in the context of learning management systems and, (2) to determine the effect of the learning styles of students on this model. An in-person survey of 258 engineering students was used to evaluate the research model. The analysis is based on structural equation modelling, specifically partial least squares. The results indicate that the research model explains use, user satisfaction, and perceived benefits of a learning management system. In addition, the Felder-Silverman learning styles (sensing-intuitive, visual-verbal; active-reflective; sequential-global) modify the strength of the relationships between the variables of the success model. 相似文献
99.
In this study, separator rejects of a closed circuit cement tube milling were dry ground in a 10-l pilot scale vertical stirred mill. Tests were done as open and closed circuit. The results were evaluated by size distributions, Blaine surface area of the products and the specific energy consumed during the tests. Mill capacity and the stirring speeds were the investigated parameters for the open circuit tests, whereas closed circuit tests were carried out at a constant stirring speed but variable discharge rate. Five speed levels used in the open circuit grinding tests are 200, 400, 600, 800 and 1000 rpm. The capacities were determined to obtain product Blaine surface areas in the limits between 2000 and 5000 cm2/g. Closed circuit tests have resulted in 87%, 182% and 452% circulating loads. 相似文献
100.
Bernab L. Rivas S. Amalia Pooley Beatriz Ruf Patricio Reyes Galo Crdenas 《应用聚合物科学杂志》2002,83(7):1501-1506
The binding capability of crosslinked poly(acrylic acid‐co‐2‐acrylamide‐2‐methyl‐1‐propane sulfonic acid) for silver(I) ions by the batch equilibrium method is investigated. The effects of the pH, temperature, time of contact, and resin–metal ion molar ratio on the retention ability are studied. The retention for silver(I) increases from 21.7% at pH 1 to 94.6% at pH 5. The adsorption capacity at pH 5 is 1.18 meq/g dry resin. The maximum load capacity at the optimum pH is determined. In order to recover the resin, elution runs in acid and basic media are carried out. The best eluent is 4M HNO3 (84.9%). Moreover, retention–elution cycles are performed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1501–1506, 2002 相似文献