Retention performance of alumina porous layer open-tubular column coated with γ-alumina nanoparticles in the highly volatile hydrocarbons separation.

An alumina porous layer open-tubular (Al2O3 PLOT) column coated with γ-alumina nanoparticles (20 nm) for highly volatile hydrocarbons (C1 to C5) separation was described. Relative to the coating of bulk alumina, this column was easily coated with dynamic method under 0.4 or 0.6 MPa for 0.53 mm or 0.32 mm capillary, respectively. And the thickness of coating layer could be tuned by repeating the coating process after column was dried and activated at 300 °C for 3 h. The effect of deactivation agents on the physicochemical properties of nano γ-alumina was characterized by X-ray diffraction (XRD) measurement and nitrogen adsorption-desorption isotherms. The influences of deactivation agents, film thickness, conditioning and column dimensions on the inertness, polarity, selectivity and elution order of C1 to C5 separation were investigated in detail. The crystallite structure and size of nano alumina were not affected by the deactivation agents and remained constant during the column making processes, whereas specific surface area, pore volume and average half pore width altered significantly. The specific surface area decreased to 125.4 m2 g-1 or 174.0 m2 g-1 and the average half pore size distributions decreased to 1.6-8.4 nm or 2.4-14.3 nm when it was deactivated with potassium chloride or sodium sulfate solution, respectively. The deactivation agents and its concentrations impacted significantly on the retention performance of column. The column deactivated with sodium sulfate solution exhibited stronger polarity and lower selectivity than which deactivated with potassium chloride solution although both columns showed good inertness. The length, internal diameter and film thickness of the column had less influence on the selectivity and resolution for C1 to C5 hydrocarbons separation, whereas the conditioning temperature and time had an obvious influence. The column had distinguished polarity and selectivity which was different from either bulk or commercial alumina columns. Typically, the hydrocarbons were baseline separated with resolutions ranging from 1.65 to 15.33 within 9 min under programmed temperature below 100 °C, and the tailing factors ranging from 1.02 to 1.07.

[Effects of substituted functional groups of cations on retention performance of ionic liquid stationary phases in gas chromatography].

Thirteen stationary phases comprising a polyvinyl imidazolium ionic liquid (IL) in which cations containing propyl, butyl, nonyl, ethyl-phenyl, or cyan methyl functional groups are paired with bis(trifluoromethanesulfonyl) imide ([NTf2]-), trifluoromethanesulfonate ([TFO]-), and hexafluorophosphate ([PF6]-) were synthesized and directly coated inside capillary fused silica tubing for use in gas chromatography. The relationship between the structure of the ILs and the McReynolds constant, thermal stability, and retention behavior of the test compound on the prepared fused silica columns was examined and discussed. The influence of the cationic substituents on retention performance of stationary phases was also studied. The variation in the retention index of the test compound with temperature was also investigated. The results indicated that the synthesized ILs have strong polarity, and that their retention performance is closely related to not only the properties of the cationic substituent but also the structure of the substituted groups and the anion. In the temperature range investigated, the variation in the retention index of the tested compounds was the same as that of conventional chromatographic stationary phases.

Interaction prediction optimization in multidisciplinary design optimization problems.

The distributed strategy of Collaborative Optimization (CO) is suitable for large-scale engineering systems. However, it is hard for CO to converge when there is a high level coupled dimension. Furthermore, the discipline objectives cannot be considered in each discipline optimization problem. In this paper, one large-scale systems control strategy, the interaction prediction method (IPM), is introduced to enhance CO. IPM is utilized for controlling subsystems and coordinating the produce process in large-scale systems originally. We combine the strategy of IPM with CO and propose the Interaction Prediction Optimization (IPO) method to solve MDO problems. As a hierarchical strategy, there are a system level and a subsystem level in IPO. The interaction design variables (including shared design variables and linking design variables) are operated at the system level and assigned to the subsystem level as design parameters. Each discipline objective is considered and optimized at the subsystem level simultaneously. The values of design variables are transported between system level and subsystem level. The compatibility constraints are replaced with the enhanced compatibility constraints to reduce the dimension of design variables in compatibility constraints. Two examples are presented to show the potential application of IPO for MDO.

[Isolation and purification of ribosome-inactivating proteins from bitter melon seeds by ion exchange chromatographic columns in series].

An anion exchange chromatographic column (DEAE-650C) and a cation exchange chromatographic column (CM-650C) were connected in series on a perfusion chromatography workstation. The crude extract of bitter melon seeds flowed through the two columns and the unadsorbed fraction on the DEAE-650C column was then directly readsorbed on the CM-650C column. Two protein components with antifungal activity were eluted from the cation exchange chromatographic column by linear salt gradient. Both of them were found to be homogeneous by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and their relative molecular masses were estimated to be about 30 000. Their N-terminal amino acid sequences are DVSFRLSGADPRSYGMFI and DVNFDLSTATAK. All of the above suggested that they are alpha-momorcharin (alpha-MMC) and beta-momorcharin (beta-MMC), respectively, two type I ribosome-inactivating proteins (Rips) of bitter melon seeds. a-MMC shows antifungal activity against Fusarium oxysporum and Pythium aphanidermatum, while beta-MMC shows antifungal activity against Pythium aphanidermatum. But they are not against Sclerotium rolfsii. In the study, quantitative recoveries of alpha-MMC and beta-MMC were 13.8% and 8.0%, respectively, from decorticated seeds by ion exchange chromatographic columns in series.

[In-situ sol-gel preparation of nano silica porous layer capillary columns and their applications in gas chromatography].

A new method is described to prepare nano silica porous layer columns by using in-situ sol-gel synthesis technology. By the interaction of ethyl acetate and water glass solution, the nano silica was synthesized on the inner surface of fused silica capillary. The influence of reaction conditions on the morphology surface area, pore volume and pore size was investigated. The experimental results demonstrate that when the mole ratio of ethyl acetate to silica was 0.82, the particle size of the superfine silica powder was in the range of 25-50 nm, the BET specific surface area was 420 m2/g, and the total pore volume was 0.68 cm3/g. The nano silica porous layer on the inner surface of fused silica capillary was formed by bonding reactions through cross-linked polysiloxane chains, and deactivated by 1 g/L KCl. The column shows sufficient selectivity, stable retention performance, proper resistance to water, good reproducibility, and unique activity. The column is suitable for the analysis of chlorofluorocarbons, halohydrocarbons, sulfur compounds, and light hydrocarbons C1-C4.

[Separation and purification of cellulase using affinity membrane].

The importance of cellulase as a means for the efficient utilization of abundant cellulose resources in the world has been well recognized. Many researchers devote themselves to studying the mechanism of the action of cellulase to cellulose so that such expensive enzyme can be used much more widely. The first step is to obtain cellulase of high purity. So purification of cellulase is the key point in this field. However, the major problem in isolation is that cellulase is a complicated enzyme system and needs too many steps for separation, and that every cellulase needs special purification processing which cannot be used for the others. A novel method for the separation of the cellulase from crude extraction of Aspergillus niger with normal qualitative filter paper processed by 5 mol/L sodium hydroxide without precipitation and desalting steps was developed. Further purification of the cellulase was achieved by using an anion-exchange column of POROS 20HQ. The cellulase purified was identified as a new endoglucanase that had relatively high endurance to pH and temperature. Its relative molecular mass was estimated to be 60,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This enzyme exhibited very high activity towards carboxymethyl cellulose (CMC) with specific activity of 350 U.mg-1 and the recovery of activity of 9.7%. Its optimum pH and temperature were 4.0 and 70 degrees C, respectively. This is a simple, rapid and efficient method for purifying cellulase with high activity.