Low temperature vibrational relaxation of carbon monoxide by light mass species

The rates of deactivation of CO(v=1) by ⁴He and by ³He have been measured between 300 K and 80 K using a pulsed laser fluorescence technique. The results show the usual strong deviation from Landau—Teller behaviour and a marked isotope effect. Comparison is made with theoretical predictions including a one-dimensional treatment which takes account of attractive forces. The present results are compared also with earlier work on the deactivation of CO by H₂, HD and D₂. It has been found that at and below 300 K D₂ is less efficient than ⁴He in the (VT) deactivation of CO (v=1) and HD is anomalously efficient. The latter effect is attributed to the involvement of rotational transitions.     

Tin in the world of today

Summary A review is given on the importance of tin as a raw material and on its various uses. Analytical problems are briefly discussed. The following subjects are dealt with: tinplate, solders, bearing metals, copper-tin alloys, other metallurgical uses, inorganic tin compounds, organotin compounds.The author has also compiled the new volume Tin of the Handbook of Analytical Chemistry (Handbuch der analytischen Chemie), edited by W. Fresenius and published by Springer-Verlag     

A study of the image contrast in Fresnel zone plate imaging of extended sources

The image contrast is experimentally demonstrated to be a particular function of various parameters including the area of the source divided by the area of the central Fresnel zone. Over 150 images were analyzed and the best fit parameters are reported. It is also shown that the best contrast is obtained by a new technique in which the projection transparency is photographically reversed before image reconstruction.     

Analysis of pp → K+K− π+π− around 1 GeV/c

Approximately 100 000 four-prong antiproton annihilations in hydrogen were measured. A clean, unbiased sample of 842 K⁺K^?π⁺π^? events was obtained. This reaction is dominated by $\text{K}{}^1\text{(～45\%)}$ and ?⁰(～20%) production, with smaller amounts of A₂⁰(～15%) and ?(～5%) production. 25% of the reactions involved double resonance production. No significant three-body resonance production is observed.     

Coupled bending and twisting of a timoshenko beam

Allowance is made for shear deflection and for rotary inertia of a non-uniform beam that executes coupled bending and twisting vibration. Principal modes are found, orthogonality conditions established and modal equations of forced motion derived.     

Derivatives and jacobians

Summary This paper develops a theory of Jacobians and partial derivatives based on definitions analogous to that of the ordinary derivative. The definitions lead to well known classes of differentiable functions. The development employs important identities in the theory of determinants. To Enrico Bompiani on his scientific Jubilee     

Nucleophilic reactivity of thiolate, hydroxide and phenolate ions towards a model O-arylated diazeniumdiolate prodrug in aqueous and cationic surfactant media

The kinetics of aromatic nucleophilic substitution of the nitric oxide‐generating diazeniumdiolate ion, DEA/NO, by thiols (L ‐glutathione, L ‐cysteine, DL ‐homocysteine, 1‐propanethiol, 2‐mercaptoethanol, and sodium thioglycolate) from the prodrug, DNP‐DEA/NO, has been examined in aqueous solution and in solutions of cationic DOTAP vesicles. Second‐order rate constants in buffered aqueous solutions (k_RS‐ = 3.48–30.9 M^?1 s^?1; 30 °C) gave a linear Brønsted plot (β_nuc = 0.414 ± 0.068) consistent with the rate‐limiting S_NAr nucleophilic attack by thiolate ions. Cationic DOTAP vesicles catalyze the thiolysis reactions with rate enhancements between 11 and 486‐fold in Tris‐HCl buffered solutions at pH 7.4. The maximum rate increase was obtained with thioglycolate ion. Thiolysis data are compared to data for nucleophilic displacement by phenolate (k_PhO‐ = 0.114 M^?1 s^?1) and hydroxide (k_OH‐ = 1.82 × 10^?2 M^?1 s^?1, 37 °C) ions. The base hydrolysis reaction is accelerated by CTAB micelles and DODAC vesicles, with the vesicles being ca 3‐fold more effective as catalysts. Analysis of the data using pseudo‐phase ion‐exchange (PIE) formalism implies that the rate enhancement of the thiolysis and base hydrolysis reactions is primarily due to reactant concentration in the surfactant pseudo‐phase. Copyright © 2009 John Wiley & Sons, Ltd.     

Chemically stable films for combinatorial fluorosensor arrays

Sensor arrays are useful for many purposes. Our interests include quasi-distributed intrinsic fiber optic arrays, those distributed along the length of an optical fiber. We have demonstrated an optical time-of-flight approach to distinguishing the fluorescence output of such arrays, as well as a synthesis of combinatorial libraries that takes advantage of a support of linear morphology to make numerous compounds in a simple manner without information loss in the synthesis. To unite these research areas, we needed an optical fiber cladding material that meets demanding synthetic and optical requirements. We have chosen the Meldal SPOCC polymer support as the best candidate for such a material and report here our initial results with this material.