Design of a fraction collector for capillary array electrophoresis

This paper describes a prototype instrument for high-throughput fraction collection with capillary array electrophoresis (CAE). The design of the system was based on a comprehensive collection approach, in which fractions from all capillaries were simultaneously collected in individual collection microwells in predefined time intervals. The location of the fractions in the microwells on the collection plate was determined by monitoring the individual zone velocities close to the end of each capillary. The collection microwell plate was fabricated from buffer-saturated agarose gel, which maintained permanent electrical contact with the separation capillaries during the collection process. Since the collection gel plate consisted of over 90% water, liquid evaporation from the collection wells was minimized. A 12-capillary array instrument was built with two-point detection using a side illumination scheme. The collection performance was demonstrated by reinjection of selected fractions of a double-stranded DNA (dsDNA) separation. The identity of collected DNA fragments was confirmed by PCR and sequencing.     

Hexafluoro­iodium(VII) hexa­fluoro­arsenate

The structure of hexa­fluoro­iodium(VII) hexa­fluoro­arsenate, IF₆AsF₆, has been determined by X‐ray diffraction using a single crystal grown from a saturated solution in anhydrous HF. IF₆AsF₆ crystallizes in the cubic space group Pa with a simple NaCl‐like ionic packing. The I and As atoms occupy the 4a and 4b Wyckoff positions, respectively, with symmetry.     

In-depth analysis of the mathematical model of polyester thermosets curing

In many areas of chemical engineering applications we have to deal with thermosetting polymer structures. One of the major processing techniques for producing such structures is the curing process. This process may be accompanied by undesirable thermal spiking phenomena during which the released energy may be trapped inside the structure. In order to predict the onset of this phenomenon models that couple reaction kinetics and heat transfer are required. The numerical model was constructed by taking into account the heat transferred by conduction through the resin, as well as the kinetics of heat generated by the cure reaction. The contributions to the rise in temperature from heat conduction and chemical reactions are different in different parts of the composite, which can be explained by the temperature–time, or conversion-time histories. The temperatures were measured in the center of a cylindrically shaped mold. Initiator concentration varied from 0.5% to 2.0% of mass fraction throughout the experiments, which governed the reaction kinetics. Introduction of the carbon base filler reduced the amount of heat generated in the composite, and as a result lowered the temperatures of the resin. The analysis of parameter sensitivity and model simulation was performed with data obtained. A good agreement was observed between experimental data and the mathematical model of the curing process in the mold.     

SmartMetals: a new method for metal identification based on fuzzy logic

This paper presents a method of searching, identifying and cross‐referencing metal alloys based on their chemical composition and/or mechanical properties, typically obtained by analysis and tests. The method uses a general pattern similar to the approach of a human expert, and relies on a classification of metals based on metallurgical expertise and fuzzy logic for identifying metals and comparing their chemical and mechanical properties. The algorithm has been tested and deployed in real applications for fast metal identification and finding of unknown equivalents, by the leading companies in the field. The same principles can also be used in other domains for similar problems, such as organic and inorganic materials identification and generic drugs comparison. Copyright © 2009 John Wiley & Sons, Ltd.     

New manganese-scaffolded organic triple-deckers based on quinoxaline, pyrazine and pyrimidine cores

The thermolytic coupling of Ph(2)CN(2) and (t-Bu)(Ph)CN(2) with doubly cyclomanganated 2,5-diphenylpyrazine and 4,6-diphenylpyrimidine afforded substantial amounts of new triple decker compounds of either C(i) and C(2) symmetry respectively containing, in both series, two eta(3)-bonded Mn(CO)(3) fragments which intervene as scaffolds sustaining the helical non-conjugated triaryl backbone. The molecular structures of two pyrazine derivatives show a typical non-parallel stacking of the aromatic rings and the encapsulation of the central pyrazyl fragment with interplanar centroid-to-centroid distances of ca. 3.5 A. The stacking of the aromatics in the triple-decker pyrimidine derivatives has been assessed by (1)H NMR experiments at low temperature. All the triple-decker-type compounds are electroactive. Pyrimidine triple-deckers can reversibly be electrochemically reduced to the corresponding anions.     

In situ photoreduction of Ag+-ions by TiO2 nanoparticles deposited on cotton and cotton/PET fabrics

The possibility of in situ photoreduction of Ag⁺-ions using TiO₂ nanoparticles deposited on cotton and cotton/PET fabrics in the presence of amino acid alanine and methyl alcohol has been discussed. The possible interaction between TiO₂, alanine and Ag⁺-ions was evaluated by FTIR analysis. The fabrication of TiO₂/Ag nanoparticles on both fabrics was confirmed by SEM, EDX, XRD, XPS and AAS analyses. Cotton and cotton/PET fabrics impregnated with TiO₂/Ag nanoparticles provided maximum reduction of Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus. Although excellent antibacterial activity was preserved after ten washing cycles, a significant amount of silver leached out from the fabrics into the washing bath. The perspiration fastness assessment revealed that smaller amounts of silver were also released from the fabrics into artificial sweat at pH 5.50 and 8.00. In addition, deposited TiO₂/Ag nanoparticles imparted maximum UV protection to fabrics.     

Kinetics of inhibition of peroxidase activity of myeloperoxidase by quercetin

The inhibition of myeloperoxidase (MPO), isolated from human neutrophils, by quercetin was investigated by following peroxidase activity of the enzyme using o-dianisidine as the substrate. The inhibition parameters (IC₅₀) were obtained by graphical analysis of the inhibition curves. A reaction mechanism, which involved the enzyme inhibition by quercetin and H₂O₂ in excess, was proposed. The rate and equilibrium constants for the proposed reaction path were calculated from experimental data. Kinetic analysis in noninhibiting H₂O₂ concentration range in the absence and the presence of quercetin revealed that the reaction mechanism underwent Michaelis–Menten kinetics. K and V values indicated that quercetin was a mixed inhibitor of MPO activity. The initial reaction rates were recalculated using the obtained results. Calculated curves fitted the experimental results within the range of experimental error. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 384–394, 2008     

Intermolecular central to axial chirality transfer in the self-assembled biphenyl containing amino acid-oxalamide gelators

Chiral amino acid and biphenyl incorporating oxalamide gelators 4-7 with large, 9 bond distance between chiral centres and biphenyl units have been studied. CD investigation of 4-octanol gel and the crystal structure of rac-4 reveal that efficient central to axial chirality transfer occurs by intermolecular interactions in gel and solid state assemblies.     

Probing the Reactivity of the Potent AgF2 Oxidizer. Part 2: Inorganic Compounds

The reactivity of Ag^IIF₂ towards forty two inorganic compounds containing oxo‐ and chloro‐ ligands, has been investigated. Five families of compounds were studied: (i) binary oxides of metals and nonmetals, (ii) ternary salts of inorganic oxo acids, (iii) concentrated or anhydrous oxo‐ acids, (iv) binary and ternary chlorides and (v) oxochlorides. At low temperatures up to 200 °C AgF₂ readily oxidizes HgO, B₂O₃, PbO₂, As₂O₅, Ag₂SO₄, LiBO₂, K₂CO₃, KVO₃, Ag₂WO₄, and AgMnO₄ with concomitant oxygen evolution. In the same conditions V₂O₅, CrO₃, MoO₃, WO₃, CuO, Tl₂O₃, I₂O₅, Re₂O₇, K₂SO₄, HgSO₄, KSO₃F, KNO₃, KClO₄, KIO₄, BaCrO₄, KMnO₄ and KReO₄ resist the action of AgF₂ but many of these compounds get oxidized at higher temperatures (up to nearly 300 °C). Substantial inertness of sulfates, chromates, nitrates, perchlorates, permanganates and perrhenates suggests that one might attempt to synthesize salts of divalent silver with these anions. AgF₂ vigorously reacts with H₂SO₄ (fuming, 30% SO₃), HSO₃Cl (100%), HClO₄ (70%), and HNO₃ (fuming, 100%) at room temperature yielding salts of Ag^I and O₂; for HClO₄ and HNO₃ pre‐cooled to ?35 °C metastable perchlorate / nitrate complexes of Ag^II are obtained. Anhydrous HSO₃F behaves similar to HSO₃CF₃ (see Part 1 of this series) yielding slow methathetical conversion of AgF₂ without concomitant redox reaction. Majority of chlorides and oxochlorides studied (AgCl, AuCl₃, KAuCl₄, WCl₆, WOCl₄, MoOCl₄, MoO₂Cl₂) react with AgF₂ at temperatures below 160 °C. Reaction with SiCl₄ (in contrast to CCl₄) is violent and very exothermic at room temperature. Liquid CrO₂Cl₂ (at room temperature) and solid WO₂Cl₂ (up to 180 °C) are kinetically inert to AgF₂. We do not observe intercalation of AgF₂ with various redox—inert oxo‐ and chloro‐ Lewis bases at the experimental conditions.