Eigenvalues of products of matrices

Let A and B be n?×?n matrices over an algebraically closed field F. The pair ( A,?B ) is said to be spectrally complete if, for every sequence c₁,…,c_n ∈F such that det (AB)=c₁ ,…,c_n , there exist matrices A′,B,′∈F,^n×n similar to A,?B, respectively, such that A′B′ has eigenvalues c₁,…,c_n . In this article, we describe the spectrally complete pairs. Assuming that A and B are nonsingular, the possible eigenvalues of A′B′ when A′ and B′ run over the sets of the matrices similar to A and B, respectively, were described in a previous article.     

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Abstract

Index abstracts     

Pr?parative Trennung von biologisch aktiven Ribonucleins?uren durch HPLC

Ohne Zusammenfassung

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Preparative separation of biologically active ribonucleic acids by HPLC

     

Multiplication in changing bases: A note on Lewis Carroll

In this note, we examine a Carrollian treatment of the base of a number system as it appears in Alice in Wonderland.     

PHOTOSENSITIZED HERBICIDAL ACTION

Abstract— The herbicidal action produced by the colorless hydrocarbon fluoranthene sprayed on the leaves of growing plants does not occur when UV radiation is removed from the light to which the plants are exposed. If the UV component of the light under which the plants are grown is augmented, the herbicidal effect of fluoranthene is increased. The mechanism of this photodynamic action is discussed.     

Synthesis of mono-amino-functionalised ferrocene, ferrocene salts and ferrocenium salts

A number of mono-amino-functionalised ferrocenes, ferrocene salts and a mono-amino-functionalised ferrocenium salt have been synthesised and characterised. This represents a novel method of accessing these important classes of molecules. In the cases of some of the ferrocene salts, there are some interesting structural features in the solid state. These include N-H...O and N-H...F hydrogen bonds.     

Plantazolicin A and B: structure elucidation of ribosomally synthesized thiazole/oxazole peptides from Bacillus amyloliquefaciens FZB42

The structures of the ribosomally synthesized peptide antibiotics from Bacillus amyloliquefaciens FZB42, plantazolicin A and B, have been elucidated by high resolving ESI-MSMS, 2D (1)H-(13)C-correlated NMR spectroscopy as well as (1)H-(15)N-HMQC/(1)H-(15)N-HMBC NMR experiments. (15)N-labeling prior to the experiments facilitated the structure determination, unveiling a hitherto unusual number of thiazoles and oxazoles formed from a linear 14mer precursor peptide. This finding further extends the number of known secondary metabolites from B. amyloliquefaciens and represents a new type of secondary metabolites from the genus Bacillus.     

Evaluation of ent-kaurenoic acid derivatives for their anticariogenic activity

Ent-kaur-16(17)-en-19-oic acid (kaurenoic acid, KA) is a tetracyclic diterpene prototype for natural anticaries agents. Six KA derivatives were prepared and their antimicrobial activity against the main microorganisms involved in the caries process evaluated. The sodium salt of KA (KA-Na) was the most active, displaying very promising MIC values for most pathogens. Time-kill assays against the primary causative agent of caries (Streptococcus mutans) indicated that KA and KA-Na only inhibited growth in the first 12 h, suggesting a bacteriostatic effect. After this period (12-24 h), their bactericidal effect was clearly noted. KA and KA-Na showed no synergy when combined with the gold standard anticariogenic (chlorhexidine dihydrochloride, CHD) in the checkerboard assays against S. mutans.     

Control of CO2 adsorption heats by the Al distribution in FER zeolites

Proper combination of template and optimized reaction conditions provides zeolite FER with homogeneous distribution of Al in the framework; this results in a new zeolite adsorbent exhibiting a constant heat of CO(2) adsorption.