Point approximation of a space-homogeneous transport equation

Summary We present an approximation method of a space-homogeneous transport equation which we prove is convergent. The method is very promising for numerical computation. Comparison of a numerical computation with an exact solution is given for the Master equation.     

Production of slow muonic hydrogen isotopes in vacuum

Muonic hydrogen isotopes (μ⁻ p, μ⁻ d, and μ⁻t) are simple quantum mechanical systems ideally suited for studies of numerous fundamental phenomena in electroweak and strong interactions as well as in applied areas such as muon chemistry or muon catalyzed fusion. Emission of muonic hydrogen isotopes into vacuum helps to overcome the limitations which are normally imposed on conventional investigations with gaseous and liquid targets. A proof of principle experiment for this new technique was performed at TRIUMF last year. Negative muons with 30 MeV/c momentum were stopped in a thin film of solid hydrogen and produced very low energy μ⁻d in vacuum. The distribution center of the normal velocity components of emitted μ⁻d atoms was measured to be ∼1 cm/μs. The yield of μ⁻d in vacuum is an increasing function of H₂ film thickness δ up to a value of δ≥1 mm.     

Submicro methods for the analysis of organic compounds : The determination of hydroxyl groups

Various procedures were examined for the determination of organic hydroxyl groups. Conventional acetylation methods could not be used on the submicro scale, but the spectrophotometric method based on esterification with 3,5-dinitrobenzoyl chloride followed by extraction of the ester and colour development with alkaline acetone proved reasonably satisfactory for aliphatic alcohols. Acidic hydroxyl groups e.g. in phenolic compounds, were titrated accurately with 0.01 M tetrabutylammonium hydroxide in benzene-methanol solution in a pyridine medium ; visual end-points or potentiometricend-points with glass-silver or glass-in-stream platinum electrode pairs were used depending on the strength of the acidic group. Some differentiating titrations were possible. A general submicro bromination method for phenols was not feasible.     

Kinetics evidence for a complex between peroxynitrous acid and titanium(IV)

The reaction between TiO(2+) and ONOOH in 0.9 M H(2)SO(4) provides evidence for direct formation, previously unobserved, of a HOONO-metal complex. The reaction proceeds via formation of an end-on complex (k = 3.0 x 10(2) M(-1) s(-1)) that rearranges to form a side-on complex (k approximately equal to 20 s(-1)). With ONOOH in excess, this rearrangement proceeds more slowly (k approximately equal to 0.1 s(-1)), probably because multiple hydrogen oxoperoxonitrate molecules form end-on complexes with oxotitanium(IV) and hinder rearrangement to the side-on complex. The absorption spectrum of the final product is that of TiO(2)(2+). Presumably, during the rearrangement or later, NO+ is lost.     

Titrimetric methods for the microdetermination of halogens in organic compounds by the rapid combustion procedure: The determination of individual halogens

A critical study has been carried out of titrimetric methods suitable for the microdetermination of each of the halogens, chlorine, bromine and iodine, in their possible organic combinations with the elements, oxygen, nitrogen and sulphur, following organic decomposition by the rapid empty tube combustion procedure.     

Stabilised phosphorus(I) and arsenic(I) iodide: readily-synthesised reagents for low oxidation state main group chemistry

Herein we report a surprisingly facile and clean synthesis of base-stabilised phosphorus(I) and arsenic(I) iodide salts, which are reagents that provide convenient access to new low oxidation state main group compounds.     

Graphical aids and scanning modes for tandem mass spectrometry

In tandem mass spectrometry, where typically one analyser is used to study the reactions of ions selected by another analyser from a mixture leaving the ion source, the output contains an additional dimension of information compared to that from conventional mass spectrometry. The increase in dimensionality tends to make the results less easy to assimilate and interpret, but the difficulties may be overcome in large measure by presenting the results in an appropriate graphical form. This review deals with the use of graphical representations of three-dimensional data to display the results of experiments in tandem mass spectrometry. Perspective diagrams or contour maps can be used to show the identity of the parent and daughter ions for all of the reactions occurring in a tandem mass spectrometer, including reactions of positive ions, reactions of negative ions and charge inversion reactions. A graphical approach is particularly valuable when double focusing mass spectrometers are used for tandem mass spectrometry, because it can make it much easier to establish the origin of the ions contributing to an observed peak and thus to determine whether interference is occurring. Factors bearing on the choice of a coordinate system are discussed. Relationships characterizing the more important simple and linked scanning modes are listed and the features to which they correspond in two selected coordinate systems are shown. Factors that influence the resolution of neighbouring peaks by sector field tandem mass spectrometers are discussed.