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Michał Blatkiewicz Anna Antecka Andrzej Górak Stanisław Ledakowicz 《Chemical Papers》2018,72(3):555-566
An approach to describe continuous partitioning of Cerrena unicolor laccase in a PEG 6000—phosphate aqueous two-phase system was proposed. The laccase was separated from crude supernatant of C. unicolor-submerged culture, and all the experiments were carried out in 25 °C and pH 7 conditions. Masses of both phases and their compositions at phase equilibrium, as well as laccase activity concentrations at different mixing points, were measured in batch experiments. An empirical short-cut method was developed which allows for calculation of mass and volume fractions of the phases, laccase concentration factors, and laccase recoveries. Theoretical predictions were verified by several experiments carried out in a special mixer-settler unit with automatic substrate feed and continuous collection of separated phases. Required concentration of the laccase was possible to achieve in a one-step extraction process in the mixer-settler unit. The predictions of the short-cut method were compared to the results of experimental measurements of phase compositions, phase volume fractions, concentration factors and enzymatic yields at steady-state operation of the extraction unit. The values of experimental results lay well within the 10% error range of the predicted values. 相似文献
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The production of activated carbon was investigated using the sequential combination of microwave and conventional heating of pistachio shells as the raw precursor with zinc chloride. Several techniques such as thermogravimetric and differential thermal analyses, infrared spectroscopy, scanning electron microscopy, and specific surface area analyses were performed to characterize the samples. The highest specific surface area value for the activated carbon prepared at a microwave power of 200?W with microwave time of 20?min, and flow rate of 50?mL?min?1 was 1468?m2?g?1. The methylene blue and iodine adsorption capacities were 331 and 1276?mg?g?1, respectively. The results were compared to those obtained using physical and chemical activation methods and showed that the sequential combination of microwave and conventional heating reasonably influenced the micropore surface area of the samples as well as the specific surface area. 相似文献
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A simple calorimetric method was employed to study the kinetics of the hydrolysis of the solventless TMOS-water mixtures, under ultrasound stimulation, as a function of the concentration of oxalic acid. The reaction rates were obtained, in relative units, from the measured thermal peak of the reaction as a non-separated function of both the sonication time and the instantaneous temperature of the medium. For concentrations of oxalic acid below 0.01 M, polycondensation reaction starts before complete hydrolysis. For concentrations of oxalic acid above 0.01 M, hydrolysis is complete and, in addition, the inverse of the time, as measured from the starting of ultrasound action until the maximum hydrolysis heat release, was found to be a reasonable relative measure of the average hydrolysis rate constant. The average hydrolysis rate constant was found to be proportional to the square root of the molar concentration of the oxalic acid. This result is in agreement with the literature if we assume small dissociation degree for the catalyst in such a solventless alkoxyde-water medium. 相似文献
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Peter van Beijeren Peter Kreis Achim Hoffmann Martina Mutter Sven Sommerfeld Werner Bäcker Andrzej Górak 《Chemical Papers》2008,62(5):458-463
Design of affinity membrane adsorbers for the purification of biomolecules requires a consideration of loading, washing, and
elution. Modelling and simulation of membrane adsorbers in literature is, however, strongly focused on the loading step. Therefore,
in this work, a complete process model which takes all the different steps into account was developed. Breakthrough experiments
in which human IgG was captured onto and eluted from Sartobind Protein A downscale modules were used for model validation
and for estimation of the required model parameters. The experimentally observed breakthrough curves were independent of the
applied flow rate and from these results linear correlations between lumped kinetic parameters and linear velocity were determined.
During elution, desorption was best described by an irreversible reaction of first order in H+ concentration. Applicability of the developed model to computer-aided design was illustrated through a process analysis study
in which the influence of the amount of loaded protein per cycle on the process yield and productivity was investigated. 相似文献
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A quasi Fourier-type duality associated with a bandlimited stationary stochastic process can be established. It comes from the spectral representation of the process and a compact support assumption for its spectral density. In this way, for essentially bounded spectral densities we have an isometry between a weightedL2space and the Hilbert space spanned by the process. We can transfer converging expansions for the exponential complex eitw in the :L2-space into a sampling expansion for the process converging in the mean square sense. 相似文献
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Anodic stripping voltammetric determination of vardenafil hydrochloride at pencil graphite electrode
Zehra Yazar Aydın Yesim Tugce Yaman Merve Yaşacan Tamer Çırak Serdar Abacı 《Journal of the Iranian Chemical Society》2017,14(4):803-810
In this paper, we present a very popular and low-cost sensor material as disposable pencil graphite electrode (PGE) system for the trace-level determination of vardenafil hydrochloride (VRL). Electrochemical behavior and determination of VRL was carried out by cyclic and square-wave adsorptive anodic stripping (SW-AdAS) voltammetry. The proposed method was highly sensitive and had a linear calibration range from 3 × 10?10 to 1 × 10?7 M with a correlation coefficient of 0.997. The limit of detection and limit of quantitation values were calculated as 1 × 10?10 and 3 × 10?10 M, respectively. Developed method with disposable PGE shows high sensitivity, selectivity and stability in a wide concentration range for VRL determination without the necessity of any modification. Additionally, this system was successfully applied in Levitra® tablets and spiked human serum in trace level of VRL. Some kinetic parameters of VRL’s were represented for the first time. The results showed that the proposed method is highly sensitive, easy and low cost for trace-level determination of VRL. 相似文献
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