Universal deformation rings and cyclic blocks

In this paper we determine the universal deformation rings of certain modular representations of finite groups which belong to cyclic blocks. The representations we consider are those for which every endomorphism is stably equivalent to multiplication by a scalar. We then apply our results to study the counterparts for universal deformation rings of conjectures about embedding problems in Galois theory. Received July 19, 1999 / Revised May 13, 2000 / Published online October 30, 2000     

Sorption properties of hydrophobically modified poly(acrylic acids) as natural organic matter model substances to pyrene

Amphiphilic natural organic matter (NOM) in soil, water and sediments plays an important role in the fate of low-soluble hydrophobic organic compounds (HOC) in the environment. Scaling NOM structural factors, which affect the transport and immobilization of HOC, is rather involved due to the complexity of the NOM materials. Sorption properties of hydrophobically modified polyacrylic (HMPA) polymers as NOM model substances for pyrene were investigated and discussed with regard to reported NOM results. Emission fluorescence spectroscopic properties of pyrene and potentiometric titrations were used to characterize the hydrophobic and acidic properties of HMPA samples. Excitation fluorescence spectroscopy allowed a speciation of pyrene molecules. Overall complexation constants β₁ and β₂ of pyrene with hydrophobic moieties (–C₈H₁₇) and (–C₁₆H₃₃) were calculated depending on the pH and electrolyte cation nature at an ionic strength of 10 mM, typical of soil solution conditions. Aggregation of HMPA molecules was detected by photon correlation spectroscopy. Normalized sorption constant K_oc values for pyrene with HMPA samples similar to reported values with NOM support recent observations on the contribution of aliphatic moieties to the binding of polyaromatic hydrocarbons (PAH). The HMPA samples also model the partitioning behavior of hydrophobic micelle-like structures of NOM.     

Boron‐Doped Tri(9,10‐anthrylene)s: Synthesis,Structural Characterization,and Optoelectronic Properties

The reaction of 9,10‐dibromo‐9,10‐dihydro‐9,10‐diboraanthracene (9,10‐dibromo‐DBA, 3 ) with two equivalents of 9‐lithio‐2,6‐ or 9‐lithio‐2,7‐di‐tert‐butylanthracene gave the corresponding 9,10‐dianthryl‐DBAs featuring two ( 4 ) or four ( 5 ) inward‐pointing tert‐butyl groups. Compound 4 exists as two atropisomers, 4 and 4′ , due to hindered rotation about the exocyclic B? C bonds. X‐ray crystallography of 5 suggests that the overall interactions between facing tert‐butyl groups are attractive rather than repulsive. Even in solution, 4 / 4′ and 5 are stable toward air and moisture for several hours. Treatment of 3 with 10‐lithio‐9‐R‐2,7‐di‐tert‐butylanthracenes carrying phenyl (R=Ph), dimesitylboryl (R=Mes₂B), or N,N‐di(p‐tolyl)amino (R=Tol₂N) groups gave the corresponding 9,10‐dianthryl‐DBA derivatives 9 – 11 in moderate to good yields. In these molecules, all four solubilizing tert‐butyl groups are outward pointing. The solid‐state structures of 4 , 5 , 9 , and 10 reveal twisted conformations about the exocyclic B? C bonds with dihedral angles of 70–90°. A significant electron‐withdrawing character was proven for the Mes₂B moiety, but no appreciable +M effect was evident for Tol₂N. Compounds 5 , 9 , and 11 show two reversible DBA‐centered reduction waves in the cyclic voltammogram. In the case of 10 , a third reversible redox transition can be assigned to the Mes₂B–anthryl substituents. The UV/Vis absorption spectrum of 5 is characterized by a very broad band at λ_max=510 nm, attributable to a twisted intramolecular charge‐transfer interaction from the anthryl donors to the DBA acceptor. The corresponding emission band shows pronounced positive solvatochromism (λ_em=567 nm, C₆H₁₂; 680 nm, CH₂Cl₂) in line with a highly polar excited state. The charge‐transfer bands of 10 and 11 , as well as the emission bands of 9 and 10 , are redshifted relative to those of 5 . The Tol₂N derivative 11 is essentially nonfluorescent in solution, but emits bright wine‐red light in the solid state.     

Modeling,simulation and adaptive process control of biotechnological processes in decentralized anaerobic treatment of domestic wastewater

Control in anaerobic wastewater treatment plants is difficult to achieve but necessary due to a high sensitivity to disturbances and process complexity. With the help of different mathematical tools, control strategies can be developed. Particularly, a well-defined mathematical model can be highly effective for design, assessment and optimization of treatment plants. However, applications directly in the control system of a treatment plant are hard to achieve due to model complexity and usually require specialized software and the engagement of experts in the subject. The objective of the present study was the development of less empirical methods for assessment and control of a decentralized anaerobic plant for the treatment of domestic wastewater. A lab-scale plant, which consisted of a two-stage anaerobic digestion process followed by an anaerobic ammonium oxidation (ANAMMOX) reactor for nitrogen removal, was used as object of study. Ordinary differential equation models were implemented to simulate the processes that took place in the treatment plant. With the help of the implemented models, control tools were developed. These tools include a standalone application for monitoring of the two-stage anaerobic digestion process and an ammonium estimator for the ANAMMOX reactor by means of artificial neural networks (ANNs). The procedures followed aimed to reduce the amount of experimental work required so they can be easily transferred from laboratory to full-scale conditions. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Stress‐Induced Stabilization of Crystals in Shape Memory Natural Rubber

In contrast to all known shape memory polymers, the melting temperature of crystals in shape memory natural rubber (SMNR) can be greatly manipulated by the application of external mechanical stress. As shown previously, stress perpendicular to the prior programming direction decreases the melting temperature by up to 40 K. In this study, we investigated the influence of mechanical stress parallel to prior stretching direction during programming on the stability of the elongation‐stabilizing crystals. It was found that parallel stress stabilizes the crystals, which is indicated by linear increase of the trigger temperature by up to 17 K. The crystal melting temperature can be increased up to 126.5 °C under constrained conditions as shown by X‐ray diffraction measurements.     

Total Chemical Synthesis of SUMO and SUMO‐Based Probes for Profiling the Activity of SUMO‐Specific Proteases

SUMO is a post‐translational modifier critical for cell cycle progression and genome stability that plays a role in tumorigenesis, thus rendering SUMO‐specific enzymes potential pharmacological targets. However, the systematic generation of tools for the activity profiling of SUMO‐specific enzymes has proven challenging. We developed a diversifiable synthetic platform for SUMO‐based probes by using a direct linear synthesis method, which permits N‐ and C‐terminal labelling to incorporate dyes and reactive warheads, respectively. In this manner, activity‐based probes (ABPs) for SUMO‐1, SUMO‐2, and SUMO‐3‐specific proteases were generated and validated in cells using gel‐based assays and confocal microscopy. We further expanded our toolbox with the synthesis of a K11‐linked diSUMO‐2 probe to study the proteolytic cleavage of SUMO chains. Together, these ABPs demonstrate the versatility and specificity of our synthetic SUMO platform for in vitro and in vivo characterization of the SUMO protease family.     

Protein/ligand binding free energies calculated with quantum mechanics/molecular mechanics

The calculation of binding affinities for flexible ligands has hitherto required the availability of reliable molecular mechanics parameters for the ligands, a restriction that can in principle be lifted by using a mixed quantum mechanics/molecular mechanics (QM/MM) representation in which the ligand is treated quantum mechanically. The feasibility of this approach is evaluated here, combining QM/MM with the Poisson-Boltzmann/surface area model of continuum solvation and testing the method on a set of 47 benzamidine derivatives binding to trypsin. The experimental range of the absolute binding energy (DeltaG = -3.9 to -7.6 kcal/mol) is reproduced well, with a root-mean-square (RMS) error of 1.2 kcal/mol. When QM/MM is applied without reoptimization to the very different ligands of FK506 binding protein the RMS error is only 0.7 kcal/mol. The results show that QM/MM is a promising new avenue for automated docking and scoring of flexible ligands. Suggestions are made for further improvements in accuracy.     

Wechselwirkungen in Kristallen. 110. Mitteilung. Die Dimorphic von (2-Pyridyl)(2-pyrimidyl)amin

Interactions in Crystals: The Dimorphism of (2-Pyridyl)(2-pyrimidyl)amine Preceding structural studies of 2-aminopyridine derivatives prove that they form polymorphic H-pair-bonded dimmers, and, therefore, (2-pyrimidyl)amine has been crystallized under different conditions. Two different monoclinic modifications are characterized by their crystal structures of the same space group P2₁/c: form I exhibits the well known herringbone motif and form II the sandwich-herringbone one. Both modifications contain almost identical planar, H-pair-bridged molecular dimmers. Crystals of form I are readily obtained from any solvent, whereas those of form II result either on fast evaporation of a Et₂O solution or by resolidification of the melt. Differential thermal analysis (DTA) and crystallization experiments at different temperatures prove, for both modifications, no transitions in the temperature range between ?25° and the melting point at 152° and, therefore the system should be monotropic. The structural and thermodynamic aspects of the (2-pyridyl)(2-pyrimidyl)amine dimorphism are discussed in comparison to those of the trimorphism observed for di(2-pyridyl)amine.