Structural Consequences of the 1,2,3-Triazole as an Amide Bioisostere in Analogues of the Cystic Fibrosis Drugs VX-809 and VX-770

Although the 1,2,3-triazole is a commonly used amide bioisostere in medicinal chemistry, the structural implications of this replacement have not been fully studied. Employing X-ray crystallography and computational studies, we report the spatial and electronic consequences of replacing an amide with the triazole in analogues of cystic fibrosis drugs in the VX-770 and VX-809 series. Crystallographic analyses quantify subtle differences in the relative positions and conformational preferences of the R¹ and R² substituents attached to the amide and triazole bioisosteres. Computational studies derived from the X-ray data highlight the improved hydrogen bonding donor and acceptor capabilities of the amide in comparison to the triazole. This analysis of the spatial and electronic differences between the amide and 1,2,3-triazole will inform medicinal chemists as they consider using the triazole as an amide bioisostere.     

Biodegradability of lubricant base stocks and fully formulated products

Increasing awareness of the environmental impact of consumer and industrial products has produced a demand for lubricants that biodegrade. There is a number of biodegradation tests that can be used on lubricants, although not all are always appropriate, as this paper explains. The CEC test is among the best known and is in use for both conventional and synthetic oils. There will, in future, be a greater movement to biodegradable oils in Europe, perhaps extending to all oils.     

Thin-film solar cells

The R&D status of cells and modules based on hydrogenated amorphous silicon (a-Si:H) and those based on CdTe and CuInSe₂ is reviewed. The stability of a-Si:H solar cells is still a major concern. Improvements have been achieved on an empirical basis by application of multijunction structures, optimization of interfaces, etc. Stabilized efficiencies of close to 10% have been reported. In parallel, the introduction of the ‘defect-pool model’ led to remarkable progress in understanding; it follows that a-SiGe:H instead of a-Si:H should be used for the i-layer (absorber). Improved cell engineering concepts, however, such as enhancement of the built-in electric field via reduction of the i-layer thickness and/or folded structures, are believed to be more promising. Polycrystalline thin-film cells based on CdTe and CuInSe₂ are not affected by inherent degradation mechanisms. the specific properties of these materials demand heterojunctions, and particular problems arise due to the polycrystallinity of the films and to the lattice mismatch and mismatch of the electronic band structures of the materials involved. These are discussed in conjunction with measures currently applied for optimizing solar cell performance. Both cell types exhibit eficiencies in the range 16-17%. Estimations of production costs and energy payback times of thin-film photovoltaic modules are reviewed (even below 1 US$ W_p⁻¹ and as low as 4 months, respectively) and environmental concerns, especially for Cd-containing cells, are summarized.     

Structure–Activity Relationships of 2‐Sufonylpyrimidines as Quorum‐Sensing Inhibitors to Tackle Biofilm Formation and eDNA Release of Pseudomonas aeruginosa

Drug‐resistant Pseudomonas aeruginosa (PA) strains are on the rise, making treatment with current antibiotics ineffective. Hence, circumventing resistance or restoring the activity of antibiotics by novel approaches is of high demand. Targeting the Pseudomonas quinolone signal quorum sensing (PQS‐QS) system is an intriguing strategy to abolish PA pathogenicity without affecting the viability of the pathogen. Herein we report the structure–activity relationships of 2‐sulfonylpyrimidines, which were previously identified as dual‐target inhibitors of the PQS receptor PqsR and the PQS synthase PqsD. The SAR elucidation was guided by a combined approach using ligand efficiency and ligand lipophilicity efficiency to select the most promising compounds. In addition, the most effective inhibitors were rationally modified by the guidance of QSAR using Hansch analyses. Finally, these inhibitors showed the capacity to decrease biofilm mass and extracellular DNA, which are important determinants for antibiotic resistance.     

Characteristics of wet‐spun and thermally treated poly acrylonitrile fibers

The performance of carbon fibers depends on the quality of the precursor and the conditions of the thermal treatment. In detail, for a PAN precursor fiber the viscosity of a spinning dope and the draw ratio during the spinning process needs to be considered. Through wet spinning, different types of PAN precursor fibers with defined spinning parameters, including solid content, solvent content in a bath, and especially draw ratio resulting in defined cross section diameters, were fabricated and analyzed with tensile tests, density investigations, SEM, TGA‐MS, FTIR, and XRD. The results show that the mechanical properties of the fibers correlate to crystallinity. The cross section diameter is strongly related to the morphology of the fibers after thermal treatment. By extending the postdrawing of PAN fibers high tenacities were obtained at the cost of the cross section shape. In addition, TGA measurements reveal trapped residues of the wet spinning process as well as show several chemical reactions takes place at the same time at different temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43698.     

Microorganisms and Cellulose Digestion in the Gut of the Woodlouse Porcellio scaber

In the common woodlouse Porcellio scaber different parts of the gut were observed with respect to microbial counts, cellulose activity, and degradation of cellulose. Cellulose is mainly digested in the anterior part of the hindgut, as was indicated by the distribution of cellulolytic activity and the decrease of cellulose content inside the gut. The cellulases woodlice utilize for the degradation of litter are mainly produced by endosymbiotic bacteria in the hepatopancreas rather than by microorganisms ingested with the food. Microorganisms ingested with the litter are digested in the anterior part of the hindgut and may provide an important food source. In the posterior hindgut, bacterial proliferation ensures microbial colonization of feces.