Dynamic peierls stress in a crystal model with slip anisotropy

The analysis of screw dislocation motion in a lattice is extended to crystals with a preferred slip direction and to force laws of the “dangling bond” type. The external strain required for uniform motion, or the corresponding Peierls stress depends critically on the shape of the interatomic potential. For particular combinations of velocity, crystal anisotropy, and force law, the external strain drops sharply—indicating some modes of dislocation motion that are almost loss-free. Although the relation between dynamic Peierls stress and dislocation width is not monotonie, it shows a general exponential decrease.     

Conformational effects in compounds with 6-membered rings—XII : The conformational equilibrium in n-methylpiperidine

The conformational equilibrium at nitrogen in N-methylpiperidines has been determined in the gas phase (ΔG°₂₈₈ ? 13.2 ± 0.4 kJ mol^?1) and for dilute solutions in several solvents (ΔG°₂₉₃ ranging from 12.5 ± 0.4 in dodecane to 10.1 ± 0.4 in chloroform) by kinetically controlled protonation of anancomeric model compounds 6 and 8 at the interface between the pipendine-containing phase and an immiscible strong acid. The conformational energy for N-methylpiperidine determined by this method is strikingly higher than earlier estimates based on less direct methods but is supported by independent evidence from the temperature dependence of ¹³C NMR chemical shifts. Reconsideration of the more important of the earlier methods indicates that these involved invalid or unproven assumptions and that the low values of ΔG° for N-methylpiperidine derived from them are not reliable.     

Analyzing convergence and synchronicity of business and growth cycles in the euro area using cross recurrence plots

Convergence and synchronisation of business and growth cycles are important issues in the efficient formulation of euro area monetary policy by the European Central Bank (ECB). Although several studies in the economics literature address the issue of synchronicity of growth within the euro area, this is the first study to address this issue using cross recurrence analysis. The main findings are that member state growth rates have largely converged since the introduction of the euro, but there is a wide degree of different synchronisation behaviours which appear to be non-linear in nature. These differences could cause problems in future implementation of a single (ECB-determined)monetary policy in the euro area.     

Heterogeneous reactions of HOI, ICl and IBr on sea salt and sea salt proxies

The heterogeneous chemistry of HOI, ICl and IBr on sea salt and sea salt proxies has been studied at 274 K using two experimental approaches: a wetted wall flow tube coupled to an electron impact mass spectrometer (WWFT-MS) and an aerosol flow tube (AFT) coupled to a differential mobility analyser (DMA) and a chemical ionisation mass spectrometer (CIMS). Uptake of all three title molecules into bulk aqueous halide salt films was rapid and controlled by gas phase diffusion. Uptake of HOI gave rise to gas-phase ICl and IBr, with the latter being the predominant product whenever Br(-) was present. Only partial release of IBr was observed due to high solubility of dihalogens in the film. ICl uptake gave the same yield of IBr as HOI uptake. Uptake of ICl on NaBr aerosol was accommodation limited with alpha = 0.018 +/- 0.004 and gas phase IBr product has a yield of 0.6 +/- 0.3. The results show that HOI can act as a catalyst for activation of bromine from sea-salt aerosols in the marine boundary layer, via the reactions: HOI(aq) + Cl + H--> ICl(aq) + H(2)O(l) and ICl(aq) + Br--> IBr(aq) + Cl.     

Toward the self-assembly of metal-organic nanotubes using metal-metal and π-stacking interactions: bis(pyridylethynyl) silver(I) metallo-macrocycles and coordination polymers

Shape-persistent macrocycles and planar organometallic complexes are beginning to show considerable promise as building blocks for the self-assembly of a variety of supramolecular materials including nanofibers, nanowires, and liquid crystals. Here we report the synthesis and characterization of a family of planar di- and tri-silver(I) containing metallo-macrocycles designed to self-assemble into novel metal-organic nanotubes through a combination of π-stacking and metal-metal interactions. The silver(I) complexes have been fully characterized by elemental analysis, high resolution electrospray ionization mass spectrometry (HR-ESI-MS), IR, (1)H and (13)C NMR spectroscopy, and the solution data are consistent with the formation of the metallo-macrocycles. Four of the complexes have been structurally characterized using X-ray crystallography. However, only the di-silver(I) complex formed with 1,3-bis(pyridin-3-ylethynyl)benzene is found to maintain its macrocyclic structure in the solid state. The di-silver(I) shape-persistent macrocycle assembles into a nanoporous chicken-wire like structure, and ClO(4)(-) anions and disordered H(2)O molecules fill the pores. The silver(I) complexes of 2,6-bis(pyridin-3-ylethynyl)pyridine and 1,4-di(3-pyridyl)buta-1,3-diyne ring-open and crystallize as non-porous coordination polymers.     

Printing polyaniline for sensor applications

In recent years, much research has focused on the development of low-cost, printed electrochemical sensor platforms for environmental monitoring and clinical diagnostics. Much effort in this area has been based on utilising the redox properties of conducting polymers, particularly polyaniline (PANI). In tackling the inherent lack of processability exhibited by these materials, several groups have examined various mass-amenable fabrication approaches to obtain suitable thin films of PANI for sensing applications. Specifically, the approaches investigated over the years include the in situ chemical synthesis of PANI, the use of sulphonated derivatives of PANI and the synthesis of aqueousbased nano-dispersions of PANI. Nano-dispersions have shown a great deal of promise for sensing applications, given that they are inkjet-printable, facilitating the patterning of conducting polymer directly to the substrate. We have shown that inkjet-printed films of PANI can be finely controlled in terms of their two-dimensional pattern, thickness, and conductivity, highlighting the level of precision achievable by inkjet printing. Utilising these nanomaterials as inkjet-printable inks opens novel, facile, and economical possibilities for conducting polymer-printed electronic applications in areas of sensing, but also many other application areas such as energy storage, displays, organic light-emitting diodes. Given that inkjet-printing is a scalable manufacturing technique, it renders possible the large-scale production of devices such as sensors for a range of applications. Several successes have emerged from our work and from the work of others in the area of applying PANI in low-cost sensor applications, which is the focus of this review.     

Contact structures on M \times S^2

We show that if a manifold $M$ admits a contact structure, then so does $M \times S^2$ . Our proof relies on surgery theory, a theorem of Eliashberg on contact surgery and a theorem of Bourgeois showing that if $M$ admits a contact structure then so does $M \times T^2$ .     

LIF studies of iodine oxide chemistry. Part 3. Reactions IO + NO3 --> OIO + NO2, I + NO3 --> IO + NO2, and CH2I + O2 --> (products): implications for the chemistry of the marine atmosphere at night

The technique of pulsed laser photolysis coupled to LIF detection of IO was used to study IO + NO(3) --> OIO + NO(2); I + NO(3) --> (products); CH(2)I + O(2) --> (products); and O((3)P) + CH(2)I(2) --> IO + CH(2)I, at ambient temperature. was observed for the first time in the laboratory and a rate coefficient of k(1 a) = (9 +/- 4) x 10(-12) cm(3) molecule(-1) s(-1) obtained. For , a value of k(2) (298 K) = (1.0 +/- 0.3) x 10(-10) cm(3) molecule(-1) s(-1) was obtained, and a IO product yield close to unity determined. IO was also formed in a close-to-unity yield in , whereas in an upper limit of alpha(3)(IO) < 0.12 was derived. The implications of these results for the nighttime chemistry of the atmosphere were discussed. Box model calculations showed that efficient OIO formation in was necessary to explain field observations of large OIO/IO ratios.     

Evaluation of the VITEK 2 Gram-negative (GN) microbial identification test card: collaborative study

A collaborative study was conducted to evaluate the performance of the VITEK 2 Gram-negative (GN) Identification card for use with the VITEK 2 automated microbial identification system. The GN test card is used in the identification of fermenting and nonfermenting Gram-negative bacilli, including the select agent organisms Brucella melitensis, Francisella tularensis, Burkholderia mallei, B. pseudomallei, and Yersinia pestis. The VITEK 2 GN card is based on 47 biochemical tests measuring carbon source utilization, inhibition and resistance, and enzymatic activities. A total of 20 laboratories representing government, industry, and private testing facilities throughout the United States participated. In this study, 720 Gram-negative inclusivity isolates were analyzed by the GN Identification method. Of the 720 well-characterized isolates, 707 were identified correctly, 0 were misidentified, 0 were unidentified, and 13 were not characterized as a Gram-negative organism. Additionally, 120 isolates exclusive of fermenting and nonfermenting Gram-negative bacilli were screened by Gram stain. A total of 117 isolates were correctly excluded. Three organisms were incorrectly characterized by Gram stain procedures, resulting in incorrect analysis and misidentification by VITEK 2 GN. The VITEK 2 GN identification method is an acceptable automated method for the rapid identification of Gram-negative bacteria.