Heng Liang

Recursion approach for moving neutralization boundary formed on IPG strips. Part I: With strong alkali rehydration buffer.

Moving neutralization boundary (MNB) is an important foundation to understand and improve IEF. However, there are obstacles in theoretical predictions of MNB on IPG strips due to the unknown local concentrations of carrier ampholytes on commercial IPG strips and the time‐varying boundary velocities. We introduce a recursion approach to extend the current MNB theories into the space–time varying MNB system. The recursion approach emphasizes the localizability of physicochemical parameters in the discrete time intervals and local positions in Lagrangian coordinates, such as local concentrations of carrier ampholytes, local OH concentrations, local boundary velocities, local judgments, etc. The boundary‐position recursion equation in a complete time sequence was presented to quantitatively predict the MNB position–time curves by distinguishing three kinds of titration cases according to NaOH concentrations in rehydration buffers. The theoretical position–time curves and local relative judgments of boundaries were satisfactorily validated by corresponding images of boundary migrations achieved from the IPG‐MNB experiments with the some typical NaOH concentrations‐bromophenol blue‐rehydration buffers on pH 4–7 IPG strips. The results achieved herein have evident significances to the development of moving reaction boundary and IEF.

Integral optimizing functional of separation efficiency

Abstract According to thermodynamics, the integral optimizing functional of separation efficiency (ΔSS), which is the mixed entropy change between initial and final states directly associated with separation efficiency, was presented to indicate integral separation efficiency for any zone separation method by further considering the entropy change from the uniform to the arbitrary distribution of solute zones. Physically, as a system property, ΔSS is equal to the amount of information that the solute system obtains from its separation surrounding, or separation system. It can be quantitatively related to the irreversibility of separation processes in the entropy balance equation, and corresponds to the extent of Boltzmann order. In separation science, ΔSS corresponds to the quantity of separated solutes. For any arbitrary distribution of solute zones, ΔSS can be calculated directly from the distributions and relative positions of solute zones and the number of moles of solutes. Thus ΔSS can be calculated directly from the separation results of chromatography and electrophoresis to indicate separation efficiency integrally and quantitatively. For example, for Gaussian distributions of zones, ΔSS can be calculated directly from the standard deviations of the peaks (σ), the distance between the centers of gravity of adjoining zones (Δx) and the number of moles of the solutes (n) or the peak height (h). A quasi-inverse relation between ΔSS and separation pureness of solutes (ϕ) was found numerically. In any effective separation process, ΔSS is always a negative value, and the more negative ΔSS is, the better the separation efficiency is. The computer simulation supported the above characters of ΔSS. The discovery of ΔSS is a part of the nonequilibrium thermodynamic separation theory, which can be used to integrally optimize and time-varying control the complete separation systems – the aggregates of solute systems and separation systems.

Effects of Astragali radix on Renal Function and its Protein Expression of IgA Nephropathy in Mice

Abstract Aim To study the protein expression of kidney tissues changes in the IgA nephropathy (IgAN) mice induced by dextran and effects of Aqueous-extracted Astragali Radix (AEAR) on IgAN mice. Methods IgAN model was established by administrating dextran to normal mice. Some of the dextran-treated mice were given AEAR 10 g·kg −1 per day as the AEAR group. To gain insights into the pathomechanism of the protective effect, two-dimensional electrophoresis (2-DE) of protein patterns of the kidney tissues samples was carried out for normal control group, untreated (IgAN model) group, and AEAR treated group, respectively. After stained by silver staining method, the images were analyzed by PDQUEST 2-D-image analysis software. Results In a 12-week pharmacological study, oral administration of AEAR to IgAN mice induced by dextran not only reduced the levels of blood urea nitrogen (BUN), creatinine (Cr) and urine protein, but also made the differential protein patterns of kidney tissue of IgAN mice observably recover. Compared with the normal control group, about 334 kidney proteins were found significantly changed in the untreated group, in which 142 proteins increased 2 folds, 61 proteins increased 5 folds and 121 protein spots decreased more than 2 folds, and 10 proteins were uniquely expressed in untreated group. Compared with the untreated group, significantly changes in AEAR treated group were found. 50% of above 334 different proteins were regulated to near normal one in AEAR treated group. In the above 10 unique proteins, 5 spots fully recovered to the un-expression state of normal control group, 4 spots observably decreased and neared the normal expression level, and 1 protein slightly increased in AEAR treated group compared with the untreated group. Conclusions AEAR was found to induce protective effect on renal function in IgAN mice and could play an important role in regulating these protein alterations, which would help us to find the target protein markers related to AEAR effects on IgAN in mice.

Proteomic analysis of human NK-92 cells after NK cell-mediated cytotoxicity against K562 cells.

To better understand the natural killer (NK) cell cytotoxicity mechanism at the proteome level, we comparatively analyzed the proteome of the human NK-92 cells which participate in NK cell-mediated cytotoxicity assay and that of control cells. Soluble proteins were separated by two-dimensional gel electrophoresis (2-DE), 75 protein spots were found to be reproducibly differentially expressed between control and cytotoxic human NK-92 cells. A total of 60 different proteins were unequivocally identified by MALDI-TOF MS coupled with database interrogation; 37 proteins were up-regulated, whereas 23 proteins were down-regulated. Western blotting analysis of he at shock protein 60 (HSP60) and cathepsin W verified their proteome results. Some of identified proteins are involved in NK-92 cytotoxicity, which is consistent with the literature. In addition, we modeled the pathway networks between differentially expressed proteins and cellular processes of secretion and exocytosis through PathwayStudio software. The results of this study help to provide insight into the molecular mechanism of NK cell cytotoxicity.

A novel thermodynamic state recursion method for description of nonideal nonlinear chromatographic process of frontal analysis

A novel thermodynamic state recursion (TSR) method, which is based on nonequilibrium thermodynamic path described by the Lagrangian-Eulerian representation, is presented to simulate the whole chromatographic process of frontal analysis using the spatial distribution of solute bands in time series like as a series of images. TSR differs from the current numerical methods using the partial differential equations in Eulerian representation. The novel method is used to simulate the nonideal, nonlinear hydrophobic interaction chromatography (HIC) processes of lysozyme and myoglobin under the discrete complex boundary conditions. The results show that the simulated breakthrough curves agree well with the experimental ones. The apparent diffusion coefficient and the Langmuir isotherm parameters of the two proteins in HIC are obtained by the state recursion inverse method. Due to its the time domain and Markov characteristics, TSR is applicable to the design and online control of the nonlinear multicolumn chromatographic systems.

Time-varying migration process of moving neutralization boundary on the immobilized pH gradient strip in the weak-base rehydration buffer.

This paper quantificationally probes into time-varying migration processes of moving neutralization boundary (MNB) on immobilized pH gradient (IPG) strip in ammonia-rehydration buffers. The time-varying migration processes are determined by both time-varying dissociation equilibria of ammonia and position-varying pH environments formed by immobilized carrier ampholytes (CAs) on the IPG strip. Thus, the local dissociation equilibria of ammonia and the position-varying pH are introduced into the recursion equation of position of MNB migrations. The theoretical position-time curves and the velocity-time curves of MNB migrations obtained by the recursion approach were satisfactorily validated by a series of images of boundary migrations from the IPG-MNB experiments by using rehydration buffers with different ammonia concentrations on pH 3-6 IPG strips. The results achieved herein have significant evidence to a quantificational understanding of the mechanism of MNB and IEF.

Simultaneous determination of two‐component isotherm parameters and lumped mass transfer coefficients in RPLC with the 0‐1 model‐inverse method

The 0-1 model-inverse method of nonequilibrium nonlinear chromatography was developed to simultaneously determine the isotherm parameters and the lumped mass transfer coefficients of the two-component systems in RPLC. By comparing the simulated elution curves with experimental curves with regard to profiles and areas, the suitable isotherm parameters and the lumped mass transfer coefficients were obtained with the 0-1 model-inverse method. With a solute cell unit width of 1×10(-3) cm, the average errors of the peak areas were 0.178% for one component and -0.40% for two components, and the numerical diffusions of the 0-1 model for the contribution to band broadening may be negligible. In addition, the results showed that the lumped mass transfer coefficients decrease as the solute concentration increases. The 0-1 model-inverse method has not only the advantages of high calculation speed (less than 10 min for one-component systems or approximately 3 h for two-component systems using an ordinary computer) and high accuracy in simultaneously obtaining thermodynamic parameters and kinetic parameters of two-component systems, but this method also possesses the potential to optimally design and control the time-variant preparative chromatographic system due to the thermodynamic state recursion and the Lagrangian-Eulerian presentation of the 0-1 model.

Optimal Control of Voltages on Two-dimensional Electrophoresis Microchips

Abstract Based on the construction characteristics of two-dimensional microfluidic electrophoretic chips (2D-EMC), an equivalent resistance model of the microchips was established to calculate the rational ranges of voltages applied in the microchip reservoirs. Through the adjustment or optimization of electrophoretic voltages according to the measurements of electroosmotic flows, a group of optimal control voltages was obtained from the reasonable value scope of the reservoir voltages with the equivalent resistance model. The optimized control voltages were successfully applied to the two-dimensional separations of Arg and Gly derivatives on 2D-EMC with chemiluminescence detection. The experiment results indicate that this method significantly reduced the trial times needed for optimizing electrophoretic voltages of 2D-EMC separation.