Angular Benzoperylenetetracarboxylic Bisimides

Benzoperylene derivatives with two angularly attached dicarboxylic imide rings, which were prepared by the Diels–Alder‐Reaction, exhibit strong fluorescence and their free peri positions allow either control of the UV/Vis spectra through their substituents or form anchor positions for the attachment of functional units. The angular chromophore 3 may be used both for fluorescent labeling such as for primary amines or enzymes or as building blocks for more complex assemblies where they may act as energy donors for FRET or electron acceptors in PET such as for photovoltaic solar cells.     

A simple adsorptive chronopotentiometric stripping method for determination of vitamin B 1 in pharmaceutical products

A new electroanalytical method for vitamin B1 determination, based on adsorptive chronopotentiometric stripping analysis and non-specific adsorption onto mercury film electrode, was developed and validated. Stripping chronopotentiograms showed a single well-defined oxidation wave corresponding to vitamin B1 at about − 0.43 V in citrate buffer pH 6.0. The most important experimental factors affecting the monitored electroanalytical response of vitamin B1 were investigated and optimised. Under the optimal experimental conditions, linear response of vitamin B1 was obtained in the concentration range of 5–50 mg dm−3, with the achieved limit of detection of 1.64 mg dm−3, and the limit of quantitation of 4.97 mg dm−3. A mean recovery of 97.1% and relative standard deviations of 3.75% were achieved. The developed electrochemical procedure was successfully applied for the determination of vitamin B1 in pharmaceutical products. The results of the proposed method were in good agreement with those obtained by parallel HPLC analyses, confirming an accuracy of the developed method.     

Using genetic programming to evolve action selection rules in traversal-based automated software testing: results obtained with the TESTAR tool

Traversal-based automated software testing involves testing an application via its graphical user interface (GUI) and thereby taking the user’s point of view and executing actions in a human-like manner. These actions are decided on the fly, as the software under test (SUT) is being run, as opposed to being set up in the form of a sequence prior to the testing, a sequence that is then used to exercise the SUT. In practice, random choice is commonly used to decide which action to execute at each state (a procedure commonly referred to as monkey testing), but a number of alternative mechanisms have also been proposed in the literature. Here we propose using genetic programming (GP) to evolve such an action selection strategy, defined as a list of IF-THEN rules. Genetic programming has proved to be suited for evolving all sorts of programs, and rules in particular, provided adequate primitives (functions and terminals) are defined. These primitives must aim to extract the most relevant information from the SUT and the dynamics of the testing process. We introduce a number of such primitives suited to the problem at hand and evaluate their usefulness based on various metrics. We carry out experiments and compare the results with those obtained by random selection and also by Q-learning, a reinforcement learning technique. Three applications are used as Software Under Test (SUT) in the experiments. The analysis shows the potential of GP to evolve action selection strategies.     

Biologically Active 1-Aminodeoxy and 1-O-Alkyl Derivatives of The Powerful D-Glucosidase Inhibitor 2,5-Dideoxy-2,5-Imino-D-Mannitol

ABSTRACT

By an Amadori rearrangement of easily available 5-azido-5-deoxy-D-glucofuranose with dibenzylamine and subsequent catalytic hydrogenation of the resulting 5-azido-1-(N,N-dibenzyl)amino-1,5-dideoxy-D-fructopyranose, 1-amino-1,2,5-trideoxy-2,5-imino-D-mannitol was obtained in only two steps and in excellent overall yield. Likewise, other amines were employed to introduce extended side chains ultimately suitable for attachment of the inhibitor to solid supports. The reported rearrangement reaction is a high yielding, convenient and apparently general entry to 1-aminodeoxyketopyranoses modified at C-5, facilitated by the ring enlargement of the aldofuranose to the ketopyranose as an additional driving force. A range of selected chain extended analogues was prepared by acylation of N-1. Inhibitors obtained exhibit K _i-values with D-glucosidases in the micromolar range. Interestingly, 1-N-acylation resulted in superior inhibitory activities, as did the addition of a hexyl chain.     

Micropeptins from Microcystis sp. collected in Kabul Reservoir,Israel

Three new micropeptins, micropeptin KR1030, KR1002 and KR998 and the known microcyclamide GL546A were isolated from the extract of Microcystis sp. bloom material collected in Kabul Reservoir, Israel. The planar structures of the compounds were determined by homonuclear and inverse-heteronuclear 2D-NMR techniques as well as high-resolution mass spectrometry. The absolute configuration of the asymmetric centres of the amino acids was studied using Marfey's method for HPLC. The inhibitory activity of the compounds was determined for the serine proteases: trypsin, chymotrypsin and elastase.     

Macroscopic damage modeling for silicon nitride

Modeling the damage of brittle materials is of great importance considering a variety of structural components. Prominent examples are high strength engineering ceramics. The present work is concerned with silicon nitride, a material with increasing relevance in industrial applications. In the sense of a hierarchical model structure, effective properties of micromechanical simulations were applied to macroscopic, phenomenological damage models for monotonous and cyclic loading. In the following, both models are introduced and the application of the cyclic damage model to a four point bending test is discussed. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stable and Storable N(CF3)2 Transfer Reagents

Fluorinated groups are essential for drug design, agrochemicals, and materials science. The bis(trifluoromethyl)amino group is an example of a stable group that has a high potential. While the number of molecules containing perfluoroalkyl, perfluoroalkoxy, and other fluorinated groups is steadily increasing, examples with the N(CF₃)₂ group are rare. One reason is that transfer reagents are scarce and metal-based storable reagents are unknown. Herein, a set of Cu^I and Ag^I bis(trifluoromethyl)amido complexes stabilized by N- and P-donor ligands with unprecedented stability are presented. The complexes are stable solids that can even be manipulated in air for a short time. They are bis(trifluoromethyl)amination reagents as shown by nucleophilic substitution and Sandmeyer reactions. In addition to a series of benzylbis(trifluoromethyl)amines, 2-bis(trifluoromethyl)amino acetate was obtained, which, upon hydrolysis, gives the fluorinated amino acid N,N-bis(trifluoromethyl)glycine.