Mechanoluminescence and acoustical emission

It is reported on the measuring of the synchronic mechanoluminescent (ML) and acoustical emission (AE). The source of both ML and AE was the mechanical deformation of organic glass, of steel and copper plates. The results confirmed the connection between MA and AE stimulated by the same deformation source.     

Purity and doping possibilities of Al2O3 and YAG molten in Mo crucibles and crystals grown from this melt

Doping possibilities of Al₂O₃ and YAG crystals grown from the melt alternatively doped with alkali earth, silicon, iron group or molybdenum ions under 98% Ar – 2% H₂ or 98% He – 2% H₂ protective atmosphere are described. Alkali earth and particularly Si ions evaporate slowly from the melt. Reduction of iron group ions was observed. Mo may enter YAG phase using a wet protective atmosphere. Al₂O₃ phase contains Mo ions if grown from the electrolyzed melt.     

DNA Dyes—Highly Sensitive Reporters of Cell Quantification: Comparison with Other Cell Quantification Methods

Cell quantification is widely used both in basic and applied research. A typical example of its use is drug discovery research. Presently, plenty of methods for cell quantification are available. In this review, the basic techniques used for cell quantification, with a special emphasis on techniques based on fluorescent DNA dyes, are described. The main aim of this review is to guide readers through the possibilities of cell quantification with various methods and to show the strengths and weaknesses of these methods, especially with respect to their sensitivity, accuracy, and length. As these methods are frequently accompanied by an analysis of cell proliferation and cell viability, some of these approaches are also described.     

Premixed Turbulent Combustion Modelling Using Level Set Approach

The paper deals with a level set approach application to SI engine combustion modelling, which is based on solving an additional transport equation to determine the flame front propagation. The presented work is an extension of the paper [6]. The influence of engine speed, air excess, swirl number, engine load as well as application of different turbulence model, in.uence of mesh coarseness and model fine-tuning constants are investigated and the results are presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of some polycyclic 1,2,4‐triazines disposing of acidic N‐H group

7‐(6‐Azauracil‐5‐yl)‐isatin 1 was converted through its thiosemicarbazone 2 to 6‐(6‐azauracil‐5‐yl)‐2,3‐dihydro‐5H‐1,2,4‐triazino[5,6‐b]indol‐3‐thione 3 and through the thiosemicarbazone of appropriate isatinic acid to 2‐(2‐thio‐6‐azauracil‐5‐yl)‐6‐(6‐azauracil‐5‐yl)‐aniline 4. The course of the cyclocondensation of this compound was studied and the reaction was found to proceed in both possible ways, resulting in a mixture of compound 3 and regioisomer 6‐(2‐thio‐6‐azauracil‐5‐yl)‐2,3‐dihydro‐5H‐1,2,4‐triazino[5,6‐b]‐indol‐3‐one 5. Substituted aniline 4 was oxidized to 2,6‐bis‐(6‐azauracil‐5‐yl)‐aniline 7 , which served for the preparation of hydrazone 8 , cyclization of which led to 1‐[2,6‐bis‐(6‐azauracil‐5‐yl)‐phenyl]‐6‐azauracil‐5‐carbonitrile 9. This is the first tricyclic 6‐azauracil with vicinal arrangement of 6‐azauracil rings.     

Monte Carlo Study of Heteroarm Star Copolymers in Good and Selective Solvents

Lattice Monte Carlo simulations of conformations of hereroarm star copolymers A_nB_n in selective solvents were performed using a special variant of the Siepman and Frenkel algorithm. The effects of solvent quality, the number and lengths of blocks on the collapse of the insoluble block A, segregation of the two types of blocks and the behavior of the soluble blocks B were studied mainly for “hairy” stars containing high numbers of long arms. The simulation shows that insoluble blocks collapse in strongly selective solvents and the gravity centers of soluble and insoluble blocks separate which suggests the possibility of the formation of non‐spherical structures.

Snapshots of star a in a very bad solvent (T = 3.00) for blocks A. There are two different views of the star with a total number of arms f = 16 and number of segments N = 300.     

Numerical solution of transonic and subsonic flow of compressible inviscid and viscous fluid

The work presents two numerical solutions of compressible flows problems with high and very low Mach numbers. Both problems are numerically solved by finite volume method and the explicit MacCormack scheme using a grid of quadrilateral cells. Moved grid of quadrilateral cells is considered in the form of conservation laws using Arbitrary Lagrangian–Eulerian method. In the first case, inviscid transonic flow through cascade DCA 8% is presented and the numerical results are compared to experimental data. The second case, numerical solution of unsteady viscous flow in the channel for upstream Mach number M_∞=0.012 and frequency of the wall motions 100 Hz is presented. The unsteady case can represent a simplified model of airflow coming from the trachea, through the glottal region with periodically vibrating vocal folds to the human vocal tract. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis of fluorinated acyclic nucleoside phosphonates with 5-azacytosine base moiety

With respect to the strong antiviral activity of (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine various types of its side chain fluorinated analogues were prepared. The title compound, (S)-1-[3-fluoro-2-(phosphonomethoxy)propyl]-5-azacytosine (FPMP-5-azaC) was synthesised by the condensation reaction of (S)-2-[(diisopropoxyphosphoryl)methoxy)-3-fluoropropyl p-toluenesulfonate with a sodium salt of 5-azacytosine followed by separation of appropriate N¹ and O² regioisomers and ester hydrolysis. Transformations of FPMP-5-azaC to its 5,6-dihydro-5-azacytosine counterpart, amino acid phosphoramidate prodrugs and systems with an annelated five-membered imidazole ring, i.e. imidazo [1,2-a][1,3,5]triazine derivatives were also carried out. 1-(2-Phosphonomethoxy-3,3,3-trifluoropropyl)-5-azacytosine was prepared from 5-azacytosine and trifluoromethyloxirane to form 1-(3,3,3-trifluoro-2-hydroxypropyl)-5-azacytosine which was treated with diisopropyl bromomethanephosphonate followed by deprotection of esters. Antiviral activity of all newly prepared compounds was studied. FPMP-5-azaC diisopropyl ester inhibited the replication of herpes viruses with EC₅₀ values that were about three times higher than that of the reference anti-HCMV drug ganciclovir without displaying cytotoxicity.     

Microfabricated liquid junction hybrid capillary electrophoresis‐mass spectrometry interface for fully automated operation

One of the challenging instrumental aspects in coupling an automated CE instrument with ESI mass spectrometry (CE‐MS) is finding the balance between the stability, reproducibility and sensitivity of the analysis and compatibility with the standard CE instrumentation. Here, we present a development of a new liquid junction based electrospray interface for automated CE‐MS, with a focus on the technical design followed by computer modeling of transport conditions as well as characterization of basic performance of the interface. This hybrid arrangement designed as a microfabricated unit attachable to the automated CE instrument allows using of a wide range of separation capillaries with respect to their diameter, length or internal coating (e.g., for suppressed electroosmotic flow). Different compositions of the ESI liquid and background electrolyte solutions can be used if needed. The microfabricated part, prepared by laser machining from polyimide, includes a self‐aligning liquid junction, a short transport channel, and a pointed sprayer for the electrospray ionization. This microfabricated part is positioned in a plastic connection block securing the separation capillary and flushing ports. Transport conditions were modelled using computer simulation and the real life performance of the interface was compared to that of a commercial sheath liquid interface. The basic performance of the interface was demonstrated by separations of peptides, proteins, and oligosaccharides.     

Combination of liquid‐based column separations with surface‐enhanced Raman spectroscopy

Surface‐enhanced Raman spectroscopy is a constantly developing analytical method providing not only high‐sensitive quantitative but also qualitative information on an analyte. Thus, it is reasonable that it has been tested as a promising detection method in column separations. Although its implementation in analytical separations is not widespread, some surprising results, like enormous signal enhancement and demonstrations of single‐molecule identifications, proved in only a few special examples, indicate the potential of the method. The high detection sensitivity and selectivity would be of paramount importance in trace analyses of biologically relevant molecules in complex matrices. However, the combination of surface‐enhanced Raman spectroscopy with column separation methods brings two principal issues. Interactions of analytes with metal substrates can cause deteriorations of separations and the detection can be affected by background electrolytes or elution agents. Thus, in principle, this review is on the experimental and methodological solutions to these problems. First, theoretical and practical aspects of Raman scattering, and excitation of surface plasmon in colloid suspensions of nanoparticles and on planar nanostructured substrates are briefly explained. Advances in experimental arrangements of on‐line and at‐line couplings with column liquid phase separation methods, including microfluidic devices, are described together with chosen analytical applications.