On the existence of asymptotically stable solutions of certain integral equations

In this paper two existence results of asymptotically stable solutions of certain integral equations are presented.     

Microfabricated porous glass channels for electrokinetic separation devices

Electrically insulated porous SiO2 channels for electrokinetic separation devices were fabricated based on a mask-less etching process for creation of high aspect ratio needles in silicon. The silicon needles are converted to SiO2 by oxidation and integrated within the interior of a fluidic channel network. The channels are about 5 microm high with a pore size of 0.5+/-0.2 microm. An electrophoretic separation of a mixture of fluorescein and 5-carboxyfluorescein using epi-fluorescence detection was performed to verify proper electrokinetic transport in the porous channels. The plate height was about 170,000 m-1 for a field strength of 170 V cm-1. In the near future, it is intended to extend the fabrication scheme to include an array of porous pillars for capillary electrochromatography experiments.     

Determination of cadmium,copper and lead in alumina based catalysts by direct solid sampling graphite furnace atomic absorption spectrometry

Trace impurities of Cd, Cu and Pb were determined in alumina based catalysts using direct solid sampling graphite furnace atomic absorption spectrometry (DSS-GF AAS). The analyzed catalysts are widely used in petrochemical processes. The following analytical parameters were evaluated: pyrolysis and atomization temperatures, feasibility of calibration with aqueous solutions, the necessity for palladium as chemical modifier and the sample mass introduced into the atomizer. Test samples between 0.05 and 8.5 mg were used. Palladium was investigated as chemical modifier but no improvement in analytical performance was obtained and its use was considered unnecessary for all elements. The results obtained by DSS-GF AAS were compared with those of inductively coupled plasma optical emission spectrometry (ICP OES) and also with conventional solution analysis by GF AAS (Sol-GF AAS). Characteristic masses were 1.4, 9 and 20 pg, for Cd, Cu and Pb, respectively. Using DSS-GF AAS the relative standard deviation was always less than 10% and the results agreed with those obtained by Sol-GF AAS and ICP OES. Calibration using aqueous solutions showed good linearity within the working range (R² better than 0.99). Limits of detection (3σ, n = 10) for Cd, Cu and Pb using the proposed procedure were 0.2, 22, and 1.2 ng g^− 1, respectively.     

Mixed-matrix membrane adsorbers for protein separation

The separation of two similarly sized proteins, bovine serum albumin (BSA) and bovine hemoglobin (Hb) was carried out using a new type of ion-exchange mixed-matrix adsorber membranes. The adsorber membranes were prepared by incorporation of various types of Lewatit ion-exchange resins into an ethylene-vinyl alcohol copolymer porous structure. The obtained heterogeneous matrices, composed of solid particles surrounded by the polymeric film, display high static and dynamic protein adsorption capacities. The effect of operational parameters such as filtration flow-rate, pH, and ionic strength on the protein separation performances was investigated for cation- as well as anion-exchange adsorber membranes. An average separation factor was calculated by numerical integration of the protein concentration in the permeate curve during the filtration run. High average separation factor values were obtained for BSA-Hb separation at physiological ionic strength with a filtration flow-rate up to 20 1/h per m2, until the protein breakthrough point at 10% of the feed concentration.     

Interference-free biosensor based on screen-printing technology and sol-gel immobilization for determination of acetaldehyde in wine

A monoenzymatic amperometric biosensor was developed for the detection of acetaldehyde. The sensor is based on the association of screen-printed carbon electrodes and aldehyde dehydrogenase immobilized by a sol-gel entrapment method. Modification of screen-printed carbon electrodes with Reinecke salt of Meldola's Blue (MBRS) resulted in highly sensitive and interference-free nicotinamide-adenine dinucleotide (NADH) detectors. Based on MBRS-mediated oxidation of NADH at -150 mV versus pseudo Ag/AgCl, acetaldehyde was determined in the range 10-260 microM, compatible with wine quality monitoring. The method of immobilization based on sol-gel entrapment was optimized to obtain the best compromise between sensitivity and operational stability. The sensor response was stable for 40 consecutive assays with methyltrimethoxysilane used as alkoxide precursor, thus allowing a possible calibration of the sensor before each measurement. The biosensors were used to analyze French wines. The method was validated with a commercially available enzymatic kit based on a standard spectrophotometric method.     

Micro-analytical and microbiological investigation of selected book papers from the nineteenth century

Books represent a very important part of the cultural heritage, due to their double characteristics: first, as a man-made material and secondly, due to the information they store. The characterization of book paper represents a very important step in developing solutions for better conservation procedures, as well as for fully understanding their provenance. The present paper describes the analytical and microbiological evaluation of a collection of books from the nineteenth century, belonging to the authors’ private collections. The samples consisted of four books printed in Romania and five printed in France. The analytical characterization was performed using optical microscopy, thermal analysis, spectroscopic methods (X-ray fluorescence, X-ray diffraction, inductively coupled plasma atomic emission spectroscopy, Fourier transform infrared spectroscopy), as well as by the evaluation of the degree of polymerization and the color change. The analyses were chosen in order to be either non-destructive or, at least, micro-destructive. The fungal loading determination was performed by plating the samples on the potato dextrose agar and Sabouraud with chloramphenicol agar media, for 28 days, followed by macroscopically and microscopically identification of mold species. The present study offers a complex methodology regarding the use of non- or micro-invasive techniques for evaluating the composition, state of degradation and potential risks related to microorganism colonization of paper artifacts.     

Ultrasonic density measurement cell design and simulation of non-ideal effects

This paper presents a theoretical analysis of a density measurement cell using an unidimensional model composed by acoustic and electroacoustic transmission lines in order to simulate non-ideal effects. The model is implemented using matrix operations, and is used to design the cell considering its geometry, materials used in sensor assembly, range of liquid sample properties and signal analysis techniques. The sensor performance in non-ideal conditions is studied, considering the thicknesses of adhesive and metallization layers, and the effect of residue of liquid sample which can impregnate on the sample chamber surfaces. These layers are taken into account in the model, and their effects are compensated to reduce the error on density measurement. The results show the contribution of residue layer thickness to density error and its behavior when two signal analysis methods are used.     

Spin state transition in LaCoO3 studied using soft x-ray absorption spectroscopy and magnetic circular dichroism

Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-L(2,3) edge, we reveal that the spin state transition in LaCoO3 can be well described by a low-spin ground state and a triply degenerate high-spin first excited state. From the temperature dependence of the spectral line shapes, we find that LaCoO3 at finite temperatures is an inhomogeneous mixed-spin state system. It is crucial that the magnetic circular dichroism signal in the paramagnetic state carries a large orbital momentum. This directly shows that the currently accepted low- or intermediate-spin picture is at variance. Parameters derived from these spectroscopies fully explain existing magnetic susceptibility, electron spin resonance, and inelastic neutron data.     

Analytic cohomology groups in top degrees of Zariski open sets in {\mathbb{P}^n}

We show that if A is a closed analytic subset of \mathbbPⁿ{\mathbb{P}^n} of pure codimension q then Hⁱ(\mathbbPⁿ\ A,F){H^i(\mathbb{P}^n{\setminus} A,{\mathcal F})} are finite dimensional for every coherent algebraic sheaf F{{\mathcal F}} and every i 3 n-[\fracn-1q]{i\geq n-\left[\frac{n-1}{q}\right]} . If n-1 3 2q we show that H^n-2(\mathbbPⁿ\ A,F)=0{n-1\geq 2q\,{\rm we show that}\, H^{n-2}(\mathbb{P}^n{\setminus} A,{\mathcal F})=0} .