Plastic plasma interaction with plasmas with growing atomic number

This paper describes the investigation of the influence of target material atomic number (Z) on the laser-produced plasma pressure. For this reason, several target materials representing a wide range of atomic numbers (Z = 3.5 - 73), i.e. plastic (CH), Al, Cu, Ag, and Ta, were used. The results presented show that the plasma pressure decreases with growing atomic number but in a limited range of Z only. For higher Z, starting approximately from Z = 47 (Ag), the plasma pressure becomes constant, as confirmed by interferometric measurements and x-ray plasma imaging.     

Preparation of 1,2-disubstituted-3-hydroxy-4(1H)-quinolinones and the influence of substitution on the course of cyclization

Synthesis of 1,2-disubstituted-3-hydroxy-4(1H)-quinolinones by the cyclization of N-substituted phenacyl or acetonyl anthranilates is described. Two methods were employed for cyclization of anthranilates. Heating in polyphosphoric acid has a wide scope of applicability. The thermal cyclization in boiling N-methylpyrrolidone is limited by steric effect.     

Improved Preparation of β‐d‐ManNAc‐(1→4)‐d‐Glc and β‐d‐TalNAc‐(1→4)‐d‐Glc Disaccharides and Evaluation of Their Activating Properties on the Natural Killer Cells NKR‐P1 and CD69 Receptors

This article has been retracted.     

4‐(9,10‐Dihydroacridin‐9‐ylidene)thiosemicarbazide and its five‐membered thiazole and six‐membered thiazine derivatives

Two methyl derivatives, five‐membered methyl 2‐{2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4‐oxo‐4,5‐dihydro‐1,3‐thiazol‐5‐ylidene}acetate, C₂₀H₁₆N₄O₃S, (I), and six‐membered 2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4H‐1,3‐thiazin‐4‐one, C₁₈H₁₄N₄OS, (II), were prepared by the reaction of the N‐methyl derivative of 4‐(9,10‐dihydroacridin‐9‐ylidene)thiosemicarbazide, C₁₄H₁₂N₄S, (III), with dimethyl acetylenedicarboxylate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are molecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thiazolidine for (I) and thiazine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N—H...O hydrogen bonds and different π–π interactions between acridine moieties and thiazolidine and thiazine rings, respectively.     

A Simple Contactless Conductivity Detector Employing a Medium Wave Radio Integrated Circuit for the Signal Treatment

A new procedure has been tested for the treatment of the alternating signal coming from a contactless conductivity detection cell. The cell consists of a polyethylene (2 mm o.d., 1.5 mm i.d.) or polytetrafluoroethylene (1.6 mm o.d., 0.8 mm i.d.) tubing, with 5 mm wide tubular electrodes placed over the tubing and separated by a 5 mm gap. An unmodulated or an amplitude‐modulated AC voltage is applied to the cell and the AC current passing through the cell is treated by a TDA 1072A integrated circuit, obtaining a signal depending on the conductivity of the quiescent or flowing solution inside the cell. Under optimized conditions, the solution conductance can be measured within a range from ca. 10 to 700 μS cm^?1, corresponding to ca. 9×10^?5 to 5×10^?3 M KCl. The detector was used to measure the conductivities of various drinking waters and the values obtained were in a good agreement with those provided by a commercial contact conductometer. It has been found that the use of unmodulated input voltage is advantageous both experimentally, and from the point of view of the quality of the analytical characteristics. The integrated circuit tested is not, however, sufficiently sensitive for application to capillary detection cells with diameters of a few tens of μm, employed in microseparation procedures.     

Preparative divergent flow IEF without carrier ampholytes for separation of complex biological samples

Efficient separation method is a crucial part of the process in which components of highly complex biological sample are identified and characterized. Based on the principles of recently newly established electrophoretic method called divergent flow IEF (DF IEF), we have tested the DF IEF instrument which is able to operate without the use of background carrier ampholytes. We have verified that during separation and focusing of sample consisting of high numbers of proteins (yeast lysate and wheat flour extract), the pH gradient of preparative DF IEF can be created by autofocusing of the sample components themselves without any addition of carrier ampholytes. In DF IEF, the proteins are separated, desalted and concentrated in one step. The fractions of yeast lysate sample, collected at the DF IEF output and subjected to gel IEF, contained the zones of proteins gradually covering the pI values from 3.7 to 8.5. In our experimental arrangement, the highest number of proteins has been found in fractions with pI values around 5.3 as detected by polyacrylamide gel IEF with CBB staining. During DF IEF, the selected protein bands have been concentrated up to 16.8‐fold.     

Potentiometric Stripping Analysis at Antimony Film Electrodes

New procedures of potentiometric stripping analysis can be based on the use of antimony film electrodes and antimony(III) salts. In this paper, antimony films are generated onto carbon paste electrodes in situ and after electrolytic preconcentration of the metals to be determined, the excess antimony(III) serves as a chemical oxidant. Moreover in acidic solutions containing halide ions, the oxidation ability of antimony(III) is adequately limited because of formation of its corresponding halide complexes. Compared with similar total substitution of traditionally used mercury(II) by bismuth(III), the use of antimony(III) offers higher sensitivity in detection of heavy metals, namely, cadmium and lead.     

Electrochemical sensors and biosensors based on heterogeneous carbon materials

Abstract  

An overview of the use of electrochemical sensors made from heterogeneous carbon materials (carbon paste electrodes, screen-printed carbon electrodes) in the field of food analysis is presented. Sensors for inorganic and organic analytes as well as biosensors are summarized.     

Correlation of acoustic and optical emission signals produced at 1064 and 532 nm laser-induced breakdown spectroscopy (LIBS) of glazed wall tiles

An acoustic signal was used for the internal standardization of laser-induced breakdown spectroscopy (LIBS) of a glazed wall tile. For the LIBS analyses, 1064 nm and 532 nm wavelengths of the Nd:YAG laser were utilized. The tile was depth profiled by a single-spot ablation from the glaze into the substrate. Some lines of major elements Si(I) 252.418, Si(I) 252.851, Al(I) 257.509, Cr(I) 295.368, Al(I) 309.271 nm and Ti(II) 334.904 nm were monitored. The decrease in the optical emissions during the ablation was successfully compensated for by normalization to the square power of the acoustic signal in the interval of 290–340 nm. This approach failed for the lines between 250–270 nm. The results were the same for both lasing wavelengths despite different irradiances. The acquired profiles are in good agreement with the reference X-ray fluorescence measurement.     

Amperometric sensing of hydrogen peroxide vapor for security screening

Rapid detection of the hydrogen peroxide precursor of peroxide explosives is required in numerous security screening applications. We describe a highly sensitive and selective amperometric detection of hydrogen peroxide vapor at an agarose-coated Prussian-blue (PB) modified thick-film carbon transducer. The sensor responds rapidly and reversibly to dynamic changes in the level of the peroxide vapor, with no apparent carry over and with a detection limit of 6 ppbv. The remarkable selectivity of the PB-based screen-printed electrode towards hydrogen peroxide leads to effective discrimination against common beverage samples. For example, blind tests have demonstrated the ability to selectively and non-invasively identify concealed hydrogen peroxide in drinking cups and bottles. The attractive performance of the new microfabricated PB-based amperometric peroxide vapor sensor indicates great potential for addressing a wide range of security screening and surveillance applications. Figure Experimental setup (left) with three electrode electrochemical Hydrogen Peroxide sensor hanging above container of “unknown” liquid. Schematic (right) demonstrating fundamental principles of operation of the sensor.