Continuous prediction technique for fast determination of cyclic steady state in simulated moving bed process

In the simulation of cyclic processes, such as simulated moving bed (SMB), the system should be equilibrated to reach a cyclic steady state (CSS) before evaluating the process performance. However, the conventional method of successive substitution is quite time-consuming. In this work, a continuous predicting method (CPM) is developed for fast determination of CSS in SMB. In CPM, the direct prediction of state variable at CSS and solving model equation are conducted alternately until CSS is reached. In order to give a guideline for the selection of the acceleration factor, CPM is applied on SMB process for enantio separation of 1,1'-bi-2-naphtol racemate and with the optimized acceleration factor, 59% of computation time saved compared with successive substitution. In addition, this method is further successfully used in a sugar separation process. Given its efficiency and simplicity, this method could provide a useful tool for SMB simulations

The role of fluconazole in the regulation of fatty acid and unsaponifiable matter biosynthesis in Schizochytrium sp. MYA 1381.

BACKGROUND(#br)Schizochytrium has been widely used in industry for synthesizing polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA). However, unclear biosynthesis pathway of PUFAs inhibits further production of the Schizochytrium. Unsaponifiable matter (UM) from mevalonate pathway is crucial to cell growth and intracellular metabolism in all higher eukaryotes and microalgae. Therefore, regulation of UM biosynthesis in Schizochytrium may have important effects on fatty acids synthesis. Moreover, it is well known that UMs, such as squalene and β-carotene, are of great commercial value. Thus, regulating UM biosynthesis may also allow for an increased valuation of Schizochytrium.(#br)RESULTS(#br)To investigate the correlation of UM biosynthesis with fatty acids accumulation in Schizochytrium, fluconazole was used to block the sterols pathway. The addition of 60 mg/L fluconazole at 48 h increased the total lipids (TLs) at 96 h by 16% without affecting cell growth, which was accompanied by remarkable changes in UMs and NADPH. Cholesterol content was reduced by 8%, and the squalene content improved by 45% at 72 h, which demonstrated fluconazole’s role in inhibiting squalene flow to cholesterol. As another typical UM with antioxidant capacity, the β-carotene production was increased by 53% at 96 h. The increase of squalene and β-carotene could boost intracellular oxidation resistance to protect fatty acids from oxidation. The NADPH was found to be 33% higher than that of the control at 96 h, which meant that the cells had more reducing power for fatty acid synthesis. Metabolic analysis further confirmed that regulation of sterols was closely related to glucose absorption, pigment biosynthesis and fatty acid production in Schizochytrium.(#br)CONCLUSION(#br)This work first reported the effect of UM biosynthesis on fatty acid accumulation in Schizochytrium. The UM was found to affect fatty acid biosynthesis by changing cell membrane function, intracellular antioxidation and reducing power. We believe that this work provides valuable insights in improving PUFA and other valuable matters in microalgae

Trichoderma reesei Cellulase Complex in Hydrolysis of Agricultural Waste of Grapefruit Peel and Orange Peel

Previous attempts have already been performed for the production of sugars and, later, bioproducts from orange peel using different Trichoderma reesei commercial cocktails in combination with other kinds of enzymes. In this study, the feasibility of simple pretreatments combined with enzymatic treatments was compared between grapefruit inner peel (GFIP), orange inner peel (OIP), grapefruit whole peel (GFWP), and orange whole peel (OWP). The four biomaterials were characterized with respect to the contents of cellulose and hemi-cellulose, elemental analysis, and Fourier transform infrared (FTIR) spectrometry. The 3,5-dinitrosalicylic acid assay demonstrated that GFIP and OIP produced 31.7% and 34.9% more reducing sugar than GFWP and OWP, respectively. Further investigation of the bioprocess showed the optimal conditions include the following: (i) a solid to liquid ratio of 4%, (ii) enzymatic activity of 0.075 U/mL, and (iii) reaction at 55 °C and a pH of 5.0. Moreover, the major products after cellulolytic hydrolysis were fructose, glucose, and cellobiose. This study provides an alternative and effective approach to extend the utilization of agricultural waste in the fields of food and energy

Kinetics of lipase-catalyzed hydrolysis of olive oil in AOT/isooctane reversed micelles

The kinetics of lipase-catalyzed hydrolysis of olive oil in AOT/isooctane reversed micellar media was studied. It was shown that the deactivation of lipase had a great influence on the reaction kinetics. Based on whether the enzyme deactivation and influences of both product and substrate on enzyme stability were included or not, four different kinetic models were established. The simulating results demonstrated that the kinetic model, which including product inhibition, enzyme deactivation and the improvements of lipase stability by both product and substrate, fit the experimental data best with an overall relative error of 4.68%. (c) 2005 Elsevier B.V. All rights reserved

Study on the number of decision variables in design and optimization of Varicol process

As a variant of simulated moving bed chromatography, Varicol process can realize flexible adsorbent allocationthrough asynchronous shifting of inlet and outlet ports. In this research, the switching strategiesfor achieving one certain average configuration were investigated. It was found the system performancedepends on the total number of switches of the four ports during one switching period and Simple-Shifting-Scheme (SSS) with four switches brings out the best performance. More importantly, SSS could be different schemes, different by a parallel shifting, but all of them result in the same performance, demonstrating that only three instead of four switching times are decision variables while designing a Varicol process. To make the design of SSS more solid, a systematic method for derivation of SSS is proposed and applied on the optimization of a Varicol process for enantioseparation of 1,1-bi-2-naphthol and reduce the solvent consumption by 17% comparing with SMB

Preparation of a Monolith with Covalently Bound Bovine Serum Albumin for Capillary Electrochromatography

Capillary electrochromatography (CEC) is important for applications in enantiomer separation. The problems associated with column fabrication bring a challenge in developing monoliths with ease of preparation, robustness of separation, enhanced mass transfer, and lower pressure drop. In this research, the covalent binding of proteins on to a monolithic matrix was investigated to overcome the drawback of loss and/or denaturing of the biomolecules from physical adsorption and encapsulation method. A chitosan/silica hybrid monolith was prepared and a protein, bovine serum albumin, was covalently immobilized on the column. The prepared monolith was evaluated using the enantioseparation of D,L-tryptophan by CEC. It was found that separation of tryptophan enantiomers with a resolution of 2.44 was achieved by using 20 mmolL-1 phosphate buffer at pH 7.5. A higherchitosan concentration was also proven to be of possible use in the synthesis with the aid of acetic acid as the solvent. The much shorter retention time and increased separation ability demonstrate the advantages of capillary column under investigation

Preparation of MIP microspheres by precipitation polymerization with 1-phenyl-1-propanol as template

Conference Name:2nd International Conference on Advances in Materials and Manufacturing Processes, ICAMMP 2011. Conference Address: Guilin, China. Time:December 16, 2011 - December 18, 2011.University of Wollongong; Northeastern University; University of Science and Technology Beijing; Hebei Polytechnic UniversityMolecular imprinting polymer microspheres were prepared by precipitation polymerization with methacrylic acid as functional monomer and 1-phenyl-1-propanol as template. The effects of synthesis conditions, including the kind of solvent, polymerization temperature, the concentration of template and initiator, rotational speed and pre-polymerization time, on the characteristics of the molecularly imprinted polymer microspheres were studied. The rebinding experiments showed that the molecularly imprinted polymer microspheres synthesized by precipitation polymerization at 60掳C, with acetonitrile as solvent and the concentrations of both template and initiator of 0.01mol L-1, have good specific recognition and higher affinity capacity

Enantiomer separations on a vancomycin stationary phase and retention mechanism of pressurized capillary electrochromatography

Several chiral drugs, promethazine, carteolol, celiprolol, and albuterol, were resolved with vancomycin as the chiral stationary phase by pressurized capillary electrochromatography (pressurized CEC) and capillary HPLC. The effects of pressure and electrical field strength on efficiency, resolution, and capacity factor in pressurized CEC were investigated. A mathematical model describing the relationship of capacity factor in pressurized CEC with voltage, pressurized flow velocity, electroosmotic mobility, and electrophoretic mobility was established, which was in good agreement with the experimental data