Determination of Propylene Glycol in Low Volume Plasma and Urine Samples of Neonates by LC with Photodiode Array Detection

In order to enhance the sensitivity and to develop a method suitable for quantification of propylene glycol (PG) in low volume neonate plasma and urine samples, several steps in earlier described high performance liquid chromatographic methods were optimised. Chromatographic separation on a reversed-phase column and ultraviolet detection resulted in cleaner chromatograms without interfering compounds. Linearity of the standard curves was validated in the concentration range 0.25?C50 mg L^?1. The lower limit of quantification was 20 times lower than in earlier described methods. Presented method was suitable for quantification of PG concentrations in low volume neonate plasma (15?C46 mg L^?1) and urine samples (20?C175 mg L^?1) enabling us to document very low renal versus non-renal contribution of PG clearance in neonates.     

Underground coal gasification: rates of post processing gas transport

Two ex-situ and one in-situ semi-pilot plant UCG experiments in the experimental mine Barbara were performed with hard coal and lignite samples. To evaluate the influence of the UCG process on the textural properties of surrounding strata and coals, samples from various locations of the coal seam and the stratum samples before and after the UCG process were collected. Mercury porosimetry, helium pycnometry, and physical adsorption of nitrogen were used for the determination of textural properties of samples. Permeation gas transport was modelled based on the knowledge of the real structure characteristics of the stratum samples by the Mean Transport-Pore Model (MTPM). Influence of the individual texture and transport parameters on the post processing gas transport through porous strata with respect to the variability of their possible values was also evaluated.     

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.