Solid-Phase Transformations in Tetraamine and Hexaamine Mixed-Ligand Complexes of Chromium(III) with Cyclic Tetraamines

We have studied solid-phase transformations in mixed-ligand complexes of chromium(III) with cyclic tetraamines. We have established that tetraamine complexes of chromium(III) with 14-membered tetraaza macrocyclic ligands are relatively thermally stable, and do not undergo isomerization in the solid state. We have observed that solid-phase reactions of ammonia substitution in hexaamine complexes with outer-sphere iodide and boron hydride anions may be accompanied by dehydrogenation processes.     

Relative Invarianten und nicht-assoziative Algebren

Ohne Zusammenfassung     

Hydrophobicity of peritoneal tissues in the rat

In this study, an inventory of the hydrophobicity of peritoneal tissues in the living rat was made. Peritoneal tissues were divided into mesentery (i.e., omentum) and parietal and visceral peritoneum and their hydrophobicity was determined by the sessile drop method. All peritoneal tissues were hydrophilic with water contact angles varying from 0 degrees to 61 degrees. Mesentery and visceral peritoneum covering the intestines were significantly more hydrophilic than parietal and other visceral peritoneal tissues. In general, visceral peritoneum was the most hydrophobic tissue, and visceral peritoneum covering the kidneys (61 degrees) and the stomach (54 degrees) was less hydrophilic than that covering the rest of the organs, i.e., spleen (49 degrees), liver (45 degrees), and bladder (41 degrees). In summary, peritoneal tissues involved in adsorptive and exchange functions and requiring lubrication are more hydrophilic than tissues with more important and protective functions.     

Proteomimetic surface fragments distinguish targets by function

The fragment-centric design promises a means to develop complex xenobiotic protein surface mimetics, but it is challenging to find locally biomimetic structures. To address this issue, foldameric local surface mimetic (LSM) libraries were constructed. Protein affinity patterns, ligand promiscuity and protein druggability were evaluated using pull-down data for targets with various interaction tendencies and levels of homology. LSM probes based on H14 helices exhibited sufficient binding affinities for the detection of both orthosteric and non-orthosteric spots, and overall binding tendencies correlated with the magnitude of the target interactome. Binding was driven by two proteinogenic side chains and LSM probes could distinguish structurally similar proteins with different functions, indicating limited promiscuity. Binding patterns displayed similar side chain enrichment values to those for native protein–protein interfaces implying locally biomimetic behavior. These analyses suggest that in a fragment-centric approach foldameric LSMs can serve as useful probes and building blocks for undruggable protein interfaces.

Foldameric local surface mimetics (LSMs) detect spots at protein surfaces and are promising building blocks in a fragment-centric design of xenobiotic structures and protein–protein interaction inhibitors.     

SOS-LUX- and LAC-FLUORO-TEST for the quantification of genotoxic and/or cytotoxic effects of heavy metal salts

The constantly increasing industrial, agricultural and domestic activities with their growing risk of contaminating fresh water and ground water by discharged compounds lead to an increasing concern focused on the quality of water. Because of their simplicity and sensitivity, bacterial tests play an important role in the detection and screening of genotoxins or cytotoxins in water.One of those bacterial tests is the SOS-LUX- and LAC-FLUORO-TEST, which is a combination of two bioassays, that simultaneously measures the genotoxicity (SOS-LUX-TEST) and the cytotoxicity (LAC-FLUORO-TEST) of substances and mixtures of substances.The SOS-LUX-TEST is based on genetically modified Salmonella typhimurium TA1535 bacteria, which have been transformed with the plasmid pPLS-1 carrying the promoterless lux operon of Photobacterium leiognathi as reporter element under the control of a DNA damage-dependent SOS promoter from ColD as sensing element. This system reacts in a dose-dependent manner to agents which induce DNA damages inside these bacterial cells with the production of bioluminescence that can easily be measured.The analogous LAC-FLUORO-TEST has been developed for the detection of cellular responses to cytotoxins. It is based on the constitutive expression of green fluorescent protein (GFP) mediated by the bacterial protein expression vector pGFPuv (Clontech, Palo Alto, USA). In response to cytotoxic agents, this system reacts with a dose-dependent reduction of GFP-fluorescence.A panel of recombinant S. typhimurium strains carrying either the SOS-LUX plasmid or the fluorescence-mediating lac-GFPuv plasmid was used to determine in parallel on one microplate the genotoxic and the cytotoxic potential of heavy metal salts like K₂Cr₂O₇, CrCl₃, ZnSO₄, CuSO₄, NiSO₄, KH₂AsO₄ and As₂O₃ at the same time. Light and fluorescence emission of untreated and chemical-treated cells were measured in a microplate luminometer-fluorometer-photometer combination and the luminescence induction as well as the fluorescence reduction were used to determine the genotoxic and/or cytotoxic potential of the heavy metal salts.     

Time to default in credit scoring using survival analysis: a benchmark study

We investigate the performance of various survival analysis techniques applied to ten actual credit data sets from Belgian and UK financial institutions. In the comparison we consider classical survival analysis techniques, namely the accelerated failure time models and Cox proportional hazards regression models, as well as Cox proportional hazards regression models with splines in the hazard function. Mixture cure models for single and multiple events were more recently introduced in the credit risk context. The performance of these models is evaluated using both a statistical evaluation and an economic approach through the use of annuity theory. It is found that spline-based methods and the single event mixture cure model perform well in the credit risk context.     

Coarse classification of constant mean curvature cylinders

We give a coarse classification of constant mean curvature (CMC) immersions of cylinders into via the loop group method. Particularly for this purpose, we consider double loop groups and a new type of ``potentials' which are meromorphic 1-forms on Riemann surfaces.

     

Darboux transforms and simple factor dressing of constant mean curvature surfaces

We define a transformation on harmonic maps ${N:\,M \to S^2}$ from a Riemann surface M into the 2-sphere which depends on a parameter ${\mu \in \mathbb{C}_*}$ , the so-called μ-Darboux transformation. In the case when the harmonic map N is the Gauss map of a constant mean curvature surface ${f:\,M \to \mathbb{R}^3}$ and μ is real, the Darboux transformation of ?N is the Gauss map of a classical Darboux transform of f. More generally, for all parameter ${\mu \in \mathbb{C}_*}$ the transformation on the harmonic Gauss map of f is induced by a (generalized) Darboux transformation on f. We show that this operation on harmonic maps coincides with simple factor dressing, and thus generalize results on classical Darboux transforms of constant mean curvature surfaces (Hertrich-Jeromin and Pedit Doc Math J DMV 2:313–333, 1997; Burstall Integrable systems, geometry, and topology, 2006; Inoguchi and Kobayashi Int J Math 16(2):101–110, 2005): every μ-Darboux transform is a simple factor dressing, and vice versa.