成像毛细管等电聚焦电泳分析糖蛋白类生物技术药物

目的建立成像毛细管等电聚焦电泳分析糖白蛋类生物技术药物的异构体和等电点的方法。方法应用优化的成像毛细管等电聚焦电泳技术,对3种糖蛋白类生物技术药物即聚乙二醇化重组人促红素(PEGlysated erythropoietin,PEG-EPO)、重组人组织型纤溶酶原激活剂TNK突变体(Recombinant human TNK mutant of tissue type plasminogen activator,rhTNK-tPA)和全人源化单抗A的异构体和等电点进行分析。结果采用优化的成像毛细管等电聚焦电泳技术,可较好地分析PEG-EPO、rhTNK-tPA和全人源化单抗A的等电点和异构体,该方法可靠、快速,具有较好的分离度和重现性。结论成像毛细管等电聚焦电泳技术可用于分析糖蛋白类生物技术药物的异构体和等电点,为保证糖蛋白类生物技术药物生产工艺的稳定性及质量控制提供了有效手段。     

Carbon nanofiber growth on thin rhodium layers

A thin layer of carbon nanofibers (CNFs) was synthesized on a thin polycrystalline rhodium (Rh) metal layer by decomposing ethylene in the presence of hydrogen. Interaction of Rh crystals with carbon results in fragmentation and formation of Rh-nanoparticles, facilitating CNF growth. CNFs are immobilized on the surface by an apparently amorphous intermediate layer containing both Rh and C. Maximum CNF growth was achieved at intermediate hydrogen concentrations. A CNF growth mechanism by (sub-) surface diffusion of carbon on Rh is suggested.     

Voltage gradient and resolution in zone electrophoresis

A theoretical equation connecting resolution in zone electrophoresis with other variables has been derived, and, in particular, resolution has been shown to be approximately proportional to the square root of the potential gradient. Some common troubles affecting resolution in zone electrophoresis are illustrated.     

Interference colors of thin oxide layers on titanium

This work deals with the characterization of the color properties of different titanium oxide films, obtained by means of anodic oxidation. The color of these oxides varies with film thickness, since it is due to light interference phenomena taking place at the metal‐oxide‐air interfaces. Color measurements were carried out by using spectrophotometry techniques: the values obtained belong to the colorimetric space CIELAB, which is defined as standard colorimetric space. The results of these analyses were related to the oxide structure, analyzed with X‐ray diffraction techniques, which was determined to be either amorphous or semicrystalline. Also the oxide thickness was taken into account. This feature was derived both from ellipsometric data and from reflectance spectra: the two data are shown to be in good adherence. Both commercial purity titanium (grade 2 ASTM) and titanium alloy Ti‐6Al‐4V substrates were investigated. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 221–228, 2008     

Photografted poly(acrylic acid) thin layers with ultra-high swelling ratios and high swelling and pH response rates

Polymeric thin films with a stimuli-responsive surface layer have many potential applications. Surface photografting is a simple and versatile method for introducing grafted chains onto polymeric substrates. However, photografted layers usually have very low swelling ratios, swelling and stimuli-response rates. This work demonstrates that photografting of acrylic acid onto polyethylene films carried out with films on the top or at the bottom of a solution leads to huge differences in the grafting reactions and the final properties of the grafted layers. The photografting reaction on the top surface of a solution is much faster, and the grafted poly(acrylic acid) layers have ultra-high equilibrium swelling ratios (>100) and very high swelling and pH response rates (in seconds).     

Purification of lysosomal cholesteryl ester hydrolase from rat liver by preparative isoelectric focusing

Ion-exchange chromatography and preparative isoelectric focusing (PIEF) were compared to produce a stable rat liver lysosomal cholesteryl ester hydrolase of high specific activity. The PIEF purification method proved to be more rapid and easier to perform. PIEF purification involved the following steps: i) osmotic shock of the lysosome fraction, ii) (NH₄)₂ SO₄ precipitation (10–70%, w/v), iii) Sepharose CL-6B gel filtration, and iv) PIEF. The enzyme was purified 60–120-fold with a yield of 2–4%. The activity of the purified enzyme was best restored by stabilizing with a 0.5% (w/v) albumin solution. The purified enzyme produced one major band on SDS-polyacrylamide gel electrophoresis having a MW of 58,500 daltons. Gel filtration showed a MW of 58,000 daltons. The optimum pH of the enzyme was 4.5, and the isoelectric point was 6.0–6.2. The specific activity of hydrolysis of cholesteryl oleate and triolein increased by similar rates during purification.     

Comparison of lipoprotein analysis by agarose gel and paper electrophoresis with analytical ultracentrifugation

A comparison has been made of human serum lipoprotein analysis by agarose gel and paper electrophoresis with a standard method of analytical ultracentrifugation. Samples were obtained from 28 patients with various disorders of lipoprotein metabolism. Correspondence was shown between the following electrophoretic and ultracentrifugal fractions: β and S_f 0–20; pre-β and S_f 20–400; α₁ and total HDL. The deviations observed with the electrophoretic methods, though sizable, were smaller than the usual clinically significant abnormalities. Semiquantitative application is there fore justified. Agarose gel electrophoresis is slightly more difficult than paper electrophoresis, but gives improved resolution of pre-β- and β-lipoproteins and better densitometric scans. Evidence was also presented that the agarose method, when used in conjuction which ultracentrifugation, may be a valuable research technique for the study of lipoprotein properties. Presented at the AOCS Meeting, Washington, D.C., April 1968.     

The effect of thin liquid layers on fluidisation characteristics

Experiments are reported which show that addition of small quantities of a non-volatile liquid to a material in Geldart's Group B causes its fluidisation behaviour to move through Group A to Group C. It is shown that this behaviour is qualitatively consistent with Molerus' analysis of the role of interparticle forces in determining fluidisation characteristics. Interparticle forces have been estimated by determining the failure point of a bed of solids suspended by upward gas flow. The results lead to a numerical adjustment of Molerus' criterion for the B/A transition, and give some insight into the physical mechanisms causing the difference in behaviour between these two Groups.     

Self-ordering of balls in compressed thin layers

Structural ordering in thin layers of SHS powders caused by uniaxial pressing in cylindrical molds was modeled in experiments with still bearing balls upon variation in mold diameter D and its inclination angle α. The results may turn helpful for elaborating practical recommendations for improving the density, uniformity, and structure of long-sized green compacts for subsequent use in SHS production of cylindrical items.     

Charge-induced formation of thin conducting layers on fluorinated graphite surface

We show that irradiation of room-temperature fluorinated graphite of C₂F composition by electron beam with a kinetic energy of 500 eV detaches the fluorine atoms from two or three top layers. The dielectric property of C₂F prevents effective penetration of the beam in depth of the sample, and electrons are accumulated between the interior layers. Comparative study of the initial C₂F sample and that after irradiation by means of X-ray photoelectron, X-ray absorption near edge structure, Raman and reflection optical spectroscopy detects a partial recovering of the π-bonds which increases the surface conductivity by more than three orders. The mechanism responsible for removal of fluorine atoms from dielectric matrix under electron irradiation is proposed and substantiated by quantum chemical calculations.     

The chemical structure and stability of plasma-deposited thin hydrocarbon layers on polyethylene

AbThe surfaces of polyethylene (PE) films were modified by deposition of layers from acetylene/ethylene monomer gases in a low-pressure radio-frequency plasma. The chemical structure of the plasma-deposited layers and their long-term stability were studied by X-ray photoelectron spectroscopy (XPS), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and contact angle measurements. These studies have shown that the plasma-deposited layers consist mainly of amorphous, short-chain, functional C_xH_y structures with aryl units. As the reactive radical centers formed during the plasma process are susceptible to further reaction with atmospheric oxygen and water, the chemical stability of these layers was investigated. This stability is ensured over the long-term, although an increase in the number of functional groups is obtained over time. It was demonstrated that the post-reactions reach a state of equilibrium after a few weeks.     

Preferentially oriented BaTiO3 thin films deposited on silicon with thin intermediate buffer layers

Barium titanate (BaTiO₃) thin films are prepared by conventional 2-methoxy ethanol-based chemical solution deposition. We report highly c-axis-oriented BaTiO₃ thin films grown on silicon substrates, coated with a lanthanum oxynitrate buffer layer of 8.9 nm. The influence of the intermediate buffer layer on the crystallization of BaTiO₃ film is investigated. The annealing temperature and buffer layer sintering conditions are optimized to obtain good crystal growth. X-ray diffraction measurements show the growth of highly oriented BaTiO₃ thin films having a single perovskite phase with tetragonal geometry. The scanning electron microscopy and atomic force microscopy studies indicate the presence of smooth, crack-free, uniform layers, with densely packed crystal grains on the silicon surface. A BaTiO₃ film of 150-nm thickness, deposited on a buffer layer of 7.2 nm, shows a dielectric constant of 270, remnant polarization (2P_r) of 5 μC/cm², and coercive field (E_c) of 60 kV/cm.     

High-speed photographic studies of impact on thin layers of emulsion explosive

A photographic study, at microsecond framing rates, has been made of the impact behaviour of thin layer samples of emulsion explosives. The experiments were performed using a drop-weight apparatus with transparent anvils. The effects of incorporating aluminium granules (∼100 μm in size) and glass microspheres (50 μm to 150 μm diameter) in the emulsion matrix were also studied. It was possible to record the flow of the emulsion both with and without additives. Of particular interest were observations of the onset and development of crystallization in the layer. In no case was there evidence for initiation of explosion.     

Visualization of primate high density lipoproteins isolated by density gradient ultracentrifugation

High density lipoproteins (HDL) isolated by density gradient ultracentrifugation from the plasma of monkeys ingesting semipurified diets are barely visible. This creates difficulty in separating HDL from other lower density lipoproteins following centrifugation and necessitates collecting large quantities of background density solution to insure complete recovery of the HDL fraction. A simple procedure is described involving the addition of β-carotene to nonhuman primate plasma prior to centrifugation which results in the delineation of HDL as a discrete yellow-orange band without affecting certain physical properties of HDL or interfering with standard lipid and protein assays.     

Corrosion of pure magnesium under thin electrolyte layers

The corrosion behavior of pure magnesium was investigated by means of cathodic polarization curve, electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) under aerated and deaerated thin electrolyte layers (TEL) with various thicknesses. Based on shot noise theory and stochastic theory, the EN results were quantitatively analyzed by using the Weibull and Gumbel distribution function, respectively. The results show that the cathodic process of pure magnesium under thin electrolyte layer was dominated by hydrogen reduction. With the decreasing of thin electrolyte layer thickness, cathodic process was retarded slightly while the anodic process was inhibited significantly, which indicated that both the cathodic and anodic process were inhibited in the presence of oxygen. The absence of oxygen decreased the corrosion resistance of pure magnesium in case of thin electrolyte layer. The corrosion was more localized under thin electrolyte layer than that in bulk solution. The results also demonstrate that there exist two kinds of effects for thin electrolyte layer on the corrosion behavior of pure magnesium: (1) the rate of pit initiation was evidently retarded compared to that in bulk solution; (2) the probability of pit growth oppositely increased. The corrosion model of pure magnesium under thin electrolyte layer was suggested in the paper.     

Growth and dissolution of thin anodic layers on GaAs: A photoelectrochemical study

Thin anodic oxide films were allowed to grow on the surface of n-type GaAs electrodes. The dissolution rate of these films was controlled by the rotating electrode technique. Thickness and formation field of the oxide were evaluated by means of chroanoamperometry. The potential distribution across the semiconductor-electrolyte junction was analysed by means of capacitance measurements. Ring-disc experiments were performed in order to study the influence of the oxide film on the redox reactions at the semiconductor electrode.     

Synthesis and characterisation of surface gradient thin conversion films on zinc coated steel

Surface gradient layers on hot-dip galvanised steel were synthesised in order to determine the barrier properties and corrosion resistance of thin amorphous conversion coatings as a function of layer thickness and processing time. For this purpose, a dip coating procedure was established that yields well-defined gradient layers. As a model system for conversion film formation on zinc coated steel, a zirconium based bath chemistry was used. The synthesised zirconium oxyhydroxide gradient films were characterised by localised electrochemical techniques, such as Scanning Kelvin Probe (SKP) and electrochemical impedance spectroscopy using an electrochemical capillary cell. Microscopic infrared reflection absorption spectroscopy (μ-FT-IRRAS) measurements and small-spot X-ray photo electron spectroscopy (XPS) were used as complementary surface analytical techniques. The applied analysing techniques provide a spatial resolution of 100-1600 μm. Thereby, a complete variation of thin film properties, such as thickness, barrier properties, corrosion resistance and chemical composition can be measured as function of the time of film growth on a sample with a length of a few centimetres. This approach allows a precise and accurate determination of structure-to-property relationships of thin conversion films. Moreover, it could be shown that a surface gradient film analysis significantly rationalises experimental time and increases the reliability of the experimental results.