Concentration and analysis of trace volatile organics in gases and biological fluids with a new solid adsorbent

Summary A new procedure for sampling, transfer, and analysis of volatile organic compounds by gas chromatography has been developed. An adsorbent trap ultimately becomes an insert for a modified injector port, and a valve system allows the sample to be transferred to a cooled precolumn and finally to the separating column. Several traps may be used for sampling (for multiple injections), and it has been established that such traps may be stored without loss of sample. The ease and reproducibility of this procedure is amenable for the investigation of volatile organic compounds involving air and water pollution, flavor, and aroma analyses, and body fluid metabolites.     

The effective Chebotarev density theorem and modular forms modulo

Suppose that (resp. ) is a modular form of integral (resp. half-integral) weight with coefficients in the ring of integers of a number field . For any ideal , we bound the first prime for which (resp. ) is zero ( ). Applications include the solution to a question of Ono (2001) concerning partitions.

     

Mössbauer studies of after-effects of auger ionization following electron capture in cobalt complexe

Abstract

The electron-capture decay of a cobalt-57 atom triggers an Auger event resulting in the loss of several electrons from the molecule in which it is incorporated. The 14.4 keV Mössbauer emission conveys information regarding the chemical forms in which the daughter iron-57 is ‘stabilized’ within 10^?7 sec following electron capture. During this time the electronic relaxation occurs completely and several tens of electron volt energy is deposited in the molecule as a result of neutralization. We find that the ethylenediamine tetra-acetate, bis-salicylaldehyde tri-ethylenetetramine, acetylacetone, and indenyl chelates fragment in a large majority of events, resulting in the formation of degraded ionic Fe²⁺ and Fe³⁺ in the former cases and C₉H₇Fe⁺ in the latter. On the other hand, highly conjugated compounds such as cobalt phthalocyanine and Vitamin B₁₂ escape fragmentation in 100 per cent of the Auger events. Tris-dipyridyl Co(III) perchlorate also escapes fragmentation in a majority of events. Apparently, the large amount of excitation energy deposited in the molecule as a consequence of charge neutralization is very rapidly (in less than 10^?13sec) and efficiently dispersed through neighboring molecules. It is a novel phenomenon.

When the dipyridyl chelate molecules are dispersed in a foreign matrix, the dissipation of charge and energy is no longer rapid and efficient and the probability of fragmentation is considerably enhanced.

We also find that part of the coordinated parent species, in the case of labeled dipyridyl chelate, arises through fragmentation followed by interaction of the electronically excited degraded iron species with a neighboring chelate molecule resulting in replacement of cobalt with an iron atom. This finding was made possible by using the chelate doped with ‘carrier-free’ ⁵⁷Co citrate.

Emission spectroscopy yields values for the isomer shifts and quadrupole splittings which differ somewhat from those obtained by absorption spectroscopy. The apparent disparities are attributed to the dissimilarities of the matrices in which the Mössbauer emitter or absorber is situated.     

Continuous-time quantum Monte Carlo method for fermions: Beyond auxiliary field framework

A numerically exact continuous-time quantum Monte Carlo algorithm for finite fermionic systems with nonlocal interactions is proposed. The scheme is particularly applicable for general multiband time-dependent correlations, since it does not invoke Hubbard-Stratonovich transformation. The present determinantal grand-canonical method is based on a stochastic series expansion for the partition function in the interaction representation. The results for the Green function and for the time-dependent susceptibility of multiorbital supersymmetric impurity model with a spin-flip interaction are presented.     

Über eine Eigenschaft der klassischen Greenschen Funktion

Ohne Zusammenfassung     

Untersuchungen über die Gleichgewichtsfiguren rotierender Flüssigkeiten,deren Teilchen einander nach dem Newtonschen Gesetze anziehen

Ohne Zusammenfassung     

New perspectives in VLSI design automation: deterministic packing by Sequence Pair

In the paper we consider a problem of packing rectangular blocks on a plane, which is known as Block Packing Problem (BPP). This problem is a central issue of the modern VLSI chips design methods. Basing on a new interpretation of the Sequence-Pair representation of the packing solution-space, which is based on Complementary Mirror Constraint Graphs (CMCG), we develop the efficient method of neighborhood exploration. This method might be able to improve the efficiency of other neighborhood-based search methods, such as simulated annealing or tabu search, as well as, to construct efficient heuristics. We illustrate application of the developed method by constructing a heuristic algorithm for solving BPP and comparing its efficiency and effectiveness to the algorithms commonly used so far.