Simple density topology

We introduce a new topology on the real line generated by the simple density points for measure. We show also that a simple category density point does not lead to a new notion. Supported by research project “Analisi Reale”, Italian PRIN funds Visiting Professor at Facoltà di Economia, Università Federico II, Naples, Italy     

Liquid phase separation of proteins based on electrophoretic effects in an electrospray setup during sample introduction into a gas-phase electrophoretic mobility molecular analyzer (CE–GEMMA/CE–ES–DMA)

Nanoparticle characterization is gaining importance in food technology, biotechnology, medicine, and pharmaceutical industry. An instrument to determine particle electrophoretic mobility (EM) diameters in the single-digit to double-digit nanometer range receiving increased attention is the gas-phase electrophoretic mobility molecular analyzer (GEMMA) separating electrophoretically single charged analytes in the gas-phase at ambient pressure. A fused-silica capillary is used for analyte transfer to the gas-phase by means of a nano electrospray (ES) unit. The potential of this capillary to separate analytes electrophoretically in the liquid phase due to different mobilities is, at measurement conditions recommended by the manufacturer, eliminated due to elevated pressure applied for sample introduction. Measurements are carried out upon constant feeding of analytes to the system. Under these conditions, aggregate formation is observed for samples including high amounts of non-volatile components or complex samples. This makes the EM determination of individual species sometimes difficult, if not impossible. With the current study we demonstrate that liquid phase electrophoretic separation of proteins (as exemplary analytes) occurs in the capillary (capillary zone electrophoresis, CE) of the nano ES unit of the GEMMA. This finding was consecutively applied for on-line desalting allowing EM diameter determination of analytes despite a high salt concentration within samples. The present study is to our knowledge the first report on the use of the GEMMA to determine EM diameters of analytes solubilized in the ES incompatible electrolyte solutions by the intended use of electrophoresis (in the liquid phase) during sample delivery. Results demonstrate the proof of concept of such an approach and additionally illustrate the high potential of a future on-line coupling of a capillary electrophoresis to a GEMMA instrument.     

On the ways of generalization of adsorption kinetic equations for the case of energetically heterogeneous surfaces

In this work, we present three different ways of incorporation of the effects of surface energetic heterogeneity in the Statistical Rate Theory kinetic equation. These ways are critically discussed and finally, we come to the conclusion that the most consistent method is based on the assumption that the adsorbing surface should not be considered as composed from independent subsystems but it should be treated as one physical entity. As an illustration, we show the numerical analysis of the experimental data concerning the adsorption of CO₂ on scandia. The estimated best-fit parameters are physically correct and consistent with the results of calorimetric measurements.     

Nano ES GEMMA and PDMA,new tools for the analysis of nanobioparticles—Protein complexes,lipoparticles, and viruses

Differential mobility analysis (DMA) is a technique suited for size analysis as well as preparative collection of airborne nanosized airborne particles. In the recent decade, the analysis of intact viruses, proteins, DNA fragments, polymers, and inorganic nanoparticles was possible when combining this method with a nano-electrospray charge-reduction source for producing aerosols from a sample solution/suspensions. Mass analysis of high molecular weight noncovalent complexes is also possible with this methodology due to the linear correlation of the electrophoretic mobility diameter and the molecular mass. In this work, we present the analysis (size and molecular mass) of high molecular weight multimers (noncovalent functional homocomplex) of Jack bean urease in a mass range from 275 kDa up to 2.5 MDa, with mainly present tri- and hexamers but also higher oligomers of the 91 kDa monomer subunit. In a second experiment, the size analysis of intact very-low-density (approximately 35 nm), low-density ( approximately 22 nm) and high-density lipoparticles (approximately 10 nm), which are heterocomplexes consisting of cholesterol, lipids, and proteins in different ratios, is presented. Results from mobility analysis were in excellent agreement with particle diameters found in literature. The last presented experiment demonstrates size analysis of a rod-like virus and selective sampling of a selected size fraction of electrosprayed, singly-charged tobacco mosaic virus particles. Sampling and subsequent transmission electron microscopic investigations of a specific size fraction (40 nm electrophoretic mobility diameter) revealed the folding of virus particles during the electrospray and charge reduction (electrical stress) as well as solvent evaporation (mechanical stress) process, leading to an observed geometry of 150 (length) x 35 (width) nm (average cylindrical geometry of unsprayed intact virus 300 x 18 nm).     

Optical particle spectrometry—Problems and prospects

Optical particle counters and spectrometers have found broad use in aerosol and atmospheric research, air pollution studies and industrial particle monitoring. The utilization of the elastic scattering of light results in increasingly portable and cost effective instrumentation due to the ongoing miniaturization of building components such as light sources and detectors. However, the non-monotonic size dependence of scattered light intensity and its variability with the changing refractive index of particles influences the function of most single optical particle counters and spectrometers. This problem is a key issue still driving the development of these instruments, first introduced more than half a century ago. Ongoing progress has resulted in not only smaller but also more sophisticated and precise instruments, but the old weakness still remains—varying response to changes of the index of refraction of particles and non-monotonic response curves. Consequently, alternative approaches exploiting elastic scattering are presented here.     

Conversion electron spectroscopy at IGISOL

Conversion elecron spectroscopy has been an important part of the nuclear spectrocopy research at the Department of Physics of the University of Jyväskylä since the commissioning of the first cyclotron in the mid 1970s. At the IGISOL facility a specialiced conversion electron spectrometer ELLI was developed in the late 1980s. The first results with ELLI were obtained using the beams from the old MC-20 cyclotron to study newly discovered isotopes of refractory fission products. In the present K130 cyclotron laboratory ELLI has been utilized in many decay-spectroscopy experiments both neutron-deficient and neutron-rich side of the valley of stability. In the early 2000s the new JYFLTRAP ion trap system overthrew ELLI from its permanent place in the IGISOL beamline. Conversion electron spectroscopy has continued with the new Penning trap that has been used in in-trap electron spectroscopy tests and post-trap electron spectroscopy is foreseen.     

Yeast-based carbon paste bioelectrode for ethanol

An amperometric bioelectrode for primary alcohols based on the incorporation of yeasts into the carbon paste matrix is reported. The response is based on the activity of alcohol dehydrogenase in yeasts. The intimate contact between the biocatalytic and sensing sites results in short response times. The addition of a redox-mediating hexacyanoferrate (III) ion greatly facilitates the detection of the enzymatically produced NADH. The effects of operating potential, carbon paste composition, concentration of coenzyme or redox mediator and other parameters are explored for optimum analytical performance. The dynamic properties of this electrode are exploited for detection in flow-injection systems, with a detection limit of 2 × 10^?6 M (9 ng) of ethanol. The relative standard deviation for repetitive injections of a 1× 10^?3 M ethanol solution over a 100-min period is 2.8%. Applicability to alcoholic beverages is illustrated. The trend in sensitivity toward different alcohols is in agreement with the known biospecificity of yeast alcohol dehydrogenase.