Ultra trace analysis of refractory metals by solid state mass spectrometry — A comparison of GDMS,SSMS and SIMS

A high resolution glow discharge mass spectrometer (GDMS VG 9000) has been used to analyze tungsten and molybdenum. Detection limits have been shown to be typically of the order of 1 ng/g or better in these matrices for integration times of 60 s per element. The results demonstrate that precisions of approximately 10% can be obtained on trace concentrations at the 10 ng/g level.     

An effective heuristic for the CLSP with set-up times

The problem of multi-item, single level, capacitated, dynamic lot-sizing with set-up times (CLSP with set-up times) is considered. The difficulty of the problem compared with its counterpart without set-up times is explained. A lower bound on the value of the objective function is calculated by Lagrangian relaxation with subgradient optimisation. During the process, attempts are made to get good feasible solutions (ie. upper bounds) through a smoothing heuristic, followed by a local search with a variable neighbourhood. Solutions found in this way are further optimised by solving a capacitated transshipment problem. The paper describes the various elements of the solution procedure and presents the results of extensive numerical experimentation.     

Mass spectrometric studies of 2-nitrosophenols

The mass spectra of 2-nitrosophenols are independent of the insertion temperature, suggesting that the compounds either do not exhibit tautomerism in the vapour phase or that the enthalpy of isomerization is low. However, their fragmentation patterns suggest tautomerism in the molecular ion.     

On the broadening of the annihilation line

The broadening of annihilation line was studied with a Ge detector. The annihilation line was deconvoluted taking into account the instrumental resolution of 1.08 keV. The P_f in several metals are found. The contribution of core electrons to annihilation is deduced.     

Unconstrained optimization based on homogeneous models

In this paper a generalized algorithm for unconstrained optimization based on homogeneous functions is presented. It is shown that this generalized algorithm reaches the minimum of a homogeneous function inn + 2 iterations and does not require finding the minimum on the one-dimensional search. The Jacobson and Oksman algorithm can be derived from this general algorithm.This work was supported by the National Research Council of Canada under grant A 7239 and by a scholarship to the author.     

A Mn36Ni4 'loop-of-loops-and-supertetrahedra' aggregate possessing a high S(T) = 26 ± 1 spin ground state

The initial use of 1,3-propanediol in mixed Mn/3d cluster chemistry has led to a Mn(III)(28)Mn(II)(8)Ni(II)(4) molecular aggregate which consists of two Mn(III)(8)Ni(2) loops and two Mn(III)(6)Mn(II)(4) supertetrahedral units and displays a high ground spin state value S(T) = 26 ± 1.     

On the equivalence of heat kernel estimates and logarithmic Sobolev inequalities for the Hodge Laplacian

In this paper we consider the Hodge Laplacian on differential k-forms over smooth open manifolds MN, not necessarily compact. We find sufficient conditions under which the existence of a family of logarithmic Sobolev inequalities for the Hodge Laplacian is equivalent to the ultracontractivity of its heat operator.We will also show how to obtain a logarithmic Sobolev inequality for the Hodge Laplacian when there exists one for the Laplacian on functions. In the particular case of Ricci curvature bounded below, we use the Gaussian type bound for the heat kernel of the Laplacian on functions in order to obtain a similar Gaussian type bound for the heat kernel of the Hodge Laplacian. This is done via logarithmic Sobolev inequalities and under the additional assumption that the volume of balls of radius one is uniformly bounded below.