Boronic acid–lectin affinity chromatography. 1. Simultaneous glycoprotein binding with selective or combined elution

We introduce a novel combination of boronic acid affinity chromatography with lectin affinity chromatography, dubbed as boronic acid–lectin affinity chromatography (BLAC). Concanavalin A and wheat germ agglutinin lectins were mixed with the pesudo-lectin boronic acid to form the BLAC affinity column and their performance was evaluated with standard glycoproteins. Optimization of the binding and elution buffers for the BLAC system is described. The BLAC columns were employed to isolate glycoproteins of interest using both selective and/or combined elution.     

Electrospray Post-Ionization Mass Spectrometry of Electrosurgical Aerosols

The feasibility of electrospray (ES) ionization of aerosols generated by electrosurgical disintegration methods was investigated. Although electrosurgery itself was demonstrated to produce gaseous ions, post-ionization methods were implemented to enhance the ion yield, especially in those cases when the ion current produced by the applied electrosurgical method is not sufficient for MS analysis. Post-ionization was implemented by mounting an ES emitter onto a Venturi pump, which is used for ion transfer. The effect of various parameters including geometry, high voltage setting, flow parameters, and solvent composition was investigated in detail. Experimental setups were optimized accordingly. ES post-ionization was found to yield spectra similar to those obtained by the REIMS technique, featuring predominantly lipid-type species. Signal enhancement was 20- to 50-fold compared with electrosurgical disintegration in positive mode, while no improvement was observed in negative mode. ES post-ionization was also demonstrated to allow the detection of non-lipid type species in the electrosurgical aerosol, including drug molecules. Since the tissue specificity of the MS data was preserved in the ES post-ionization setup, feasibility of tissue identification was demonstrated using different electrosurgical methods.     

Assessment of sample cleanup and matrix effects in the pesticide residue analysis of foods using postcolumn infusion in liquid chromatography-tandem mass spectrometry

Matrix effect profiles can be used to visualize the effect of the sample matrix to the data signals occurring in a chromatogram. In the present study these profiles were generated by postcolumn infusion of a standard pesticide mix with extracts of different food matrices prepared by the QuEChERS method. Complete raw extracts as well as individual clean-up steps were analyzed. This allowed for a detailed comparison of the interferences caused by the matrix effects from various food samples. It also gave an idea about the efficiency of matrix reduction processes. When analyzing the individual clean-up extracts of the QuEChERS method just a slight reduction of matrix effects could be observed from step to step. Matrices causing strong signal effects in the results of the raw extracts also have strong effects after the final clean-up step. Some of the components responsible for the matrix effects show an extremely high retention time. After the injection of extracts from rocket or different types of tea, significant ion suppressions occurred even after rinsing the analytical column for a long time. The experiments have shown that similar matrices can produce different matrix effect profiles. For example, for black teas and green teas significantly different matrix effect profiles were obtained, while the matrix effects of teas within one of these groups were exactly the same. Analogous results could be found for citrus fruits. In order to overcome interfering matrix effects, analytical systems equipped with different electrospray ion sources were tested. Furthermore, profiles of diluted food extracts were generated. Dilution led to a significant decrease in the matrix effects.     

Immobilized Sonogashira catalyst systems: new insights by multinuclear HRMAS NMR studies

A new chelate phosphine linker and its Pd and Cu complexes have been synthesized and immobilized. The solvent impact on these immobilized species, their mobility, and coordination preferences have been studied in situ by HRMAS (High-Resolution Magic Angle Spinning) NMR. The catalyst recycling characteristics match the HRMAS results.     

Surface properties of silicon oxide films deposited using low-pressure dielectric barrier discharge

The deposition of SiO_X films from low-pressure dielectric barrier discharge plasmas has been investigated using tetraethoxysilane (TEOS)/O₂ as the feed gas. Films were analyzed using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), AFM-based nanoindentation/nanowear techniques, and conductive AFM. Film deposition rates and hydrocarbon incorporation in the SiO_X film decrease with addition of O₂. High-quality SiO_X films with extremely low surface roughness are deposited at high oxidant concertrations. Addition of oxidant to the feed gas leads to a change in the SiO_X film structure from precursor-like to a dense SiO_X structure. The SiO_X films deposited with TEOS/O₂ plasmas were found to have soft surface layers, 0.5-1.5 nm thick, which contribute to an improvement of their field emission properties. The effect of gas phase compositions on the surface properties of the conductive surface layer was discussed.     

High capacity organic monoliths for the simultaneous application to biopolymer chromatography and the separation of small molecules

A method for controlling the mesoporous structure of monolithic organic copolymers is presented by systematic variation in polymerisation time, employing poly(p-methylstyrene-co-1,2-(p-vinylphenyl)ethane) (MS/BVPE) as a representative styrene system. Decreasing the time of polymerisation introduces a considerable fraction of mesopores (up to 20% of the total pore volume), while keeping the support permeability reasonable high (～1.3 × 10^?14 m²). Monolith structures, prepared in such a manner, enable efficient (typically around 70,000 plates/m) and fast separation of low-molecular-weight compounds, whereas their performance towards biopolymers is comparable to column supports, fabricated according to typically used protocols (polymerisation time >12 h and thus monomer conversion >98%). The polymerisation time is hence a valuable tool to tailor the fraction of support flow-channels, macropores as well as mesopores, which is shown dramatically to influence the chromatographic separation characteristics of the respective column. This way, the preferred applicability of organic (styrene) monolithic copolymers can be extended to the separation of small molecules beyond biopolymer chromatography.     

Thermal wave interference

Thermal waves are used in nondestructive testing for defect analysis by lock-in-thermography. A thermal wave field contains useful information about material and component properties, such as layer thickness or reflection coefficients of internal boundaries. Only the exact knowledge of the thermal wave field enables quantitative evaluation of these parameters. For example, a calculated wave field can be used for deconvolution of lock-in-thermography images as it provides a point spread function and therefore gives a better lateral resolution. For a better knowledge of thermal wave fields, basic experiments concerning interference effects are presented in this paper.     

Polysaccharide-based aerogels as drug carriers

The application of aerogels as drug delivery system was successfully demonstrated for silica aerogels previously. However, being biocompatible silica matrices are not biodegradable, which is a certain disadvantage for a number of pharmaceutically oriented applications. For these purposes biodegradable materials are beneficial. Supercritical drying of polysaccharide gels results in highly porous biodegradable aerogel matrices with large surface areas. Structural properties of the polysaccharide aerogels depend on the preparation method and chemical nature of the gel phase. In this work different polysaccharide precursors (starch, alginate) were used to produce aerogels, which later on were loaded with the drugs ibuprofen and paracetamol. Furthermore release kinetics was studied in vitro. Thereby it has been shown that the release rate depends primary on the properties of the matrix. The presented results demonstrate for the first time the high potential of polysaccharide aerogels for pharmaceutical applications.     

Control of rotary lawn mower noise

The current state of knowledge regarding the noise generated by rotary lawn mowers is reviewed, with emphasis on the role of the rotating blade. Noise control methods are discussed and evaluated.