Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Sixteen carbamate pesticides that belong to four chemical classes (oxime-N-methylcarbamates, aryl N-methylcarbamates, N-phenylcarbamates, and methyl esters of substituted carbamic acids) were investigated via three different commercially available thermospray interfaces and ion sources that exhibit wide differences in source geometry. Comparisons were made between the three interfaces with respect to ion formation and sensitivity of detection. Experimental parameters were standardized to obtain comparable experimental conditions. Very similar mass spectra for most carbamates were obtained that illustrate independence from the geometry of the ionization and desolvation chambers of the interfaces. These findings are in sharp contrast to several literature reports. However, thermally labile carbamates gave unsatisfactory results with regard to spectral compatibility between the interfaces. Such differences were due to thermally assisted hydrolysis reactions that occur in the vaporizer probe prior to ionization and reflect differences in the vaporizer designs. The study proves conclusively that comparable spectra can be obtained under thermospray with different interfaces and mass spectrometers.     

Qualitative and quantitative determination of X-ray trajectories

X-Ray trajectories are qualitatively determined only from the behaviour of the potential (of the lattice distance) in crystals with x-dependent deformation gradients. the quantitative calculations show the varying degrees of sensitivity of X-ray trajectories to deformation for different radiations, different orders of reflection and different maximum values of relative change of lattice distance.     

Estimates on binomial sums of partition functions

Let p(n) denote the partition function and define where p(0)= 1. We prove that p(n,k) is unimodal and satisfies for fixed n≥ 1 and all 1≤k≤n. This result has an interesting application: the minimal dimension of a faithful module for a k-step nilpotent Lie algebra of dimension n is bounded by p(n,k) and hence by , independently of k. So far only the bound n ^{n −1} was known. We will also prove that for n≥ 1 and . Received: 17 December 1999     

Zusammenhang zwischen Gitterdeformation und Verfärbungserscheinungen in synthetischen Quarzeinkristallen

In synthetic quartz monocrystals with fringes of smoky colouration perpendicular to the growth direction a connection, between the absorption in the optical range and the change of the lattice parameter in areas of different colouration exists in that kind that they are proportional to each other.