Fully-Naphthalenoid Hydrocarbons: Enumeration and Classification

Abstract

A fully-naphthalenoid system (or simply fully-naphthalenoid) is a benzenoid where all vertices can be covered by disjoint naphthalene units. Invariants of these systems are studied with special emphasis on the C_nH_s formulae. An extensive enumeration of fully-naphthalenoids by means of a computer program is reported. A detailed classification of the numbers includes the symmetry distribution and an enumeration of the C_nH_s isomers. The forms of the smallest fully-naphthalenoids are displayed together with their Kekulé structure counts.     

COD and AOX Removal and Biodegradability Assessment for Fenton and O3/UV Oxidation Processes: A Case Study from a Graphical Industry Wastewater

Due to process stability and excellent effluent quality, the use of membrane processes is rapidly expanding. However, a drawback is the production of concentrates and their proper disposal. In this study, reverse osmosis concentrate was treated by Fenton and O₃/UV oxidation processes. The concentrate contains halogenated compounds, recalcitrant COD and low biodegradability. The removal of halogenated compounds and the enhancement of biodegradability were examined. Comparing the investigated processes, Fenton oxidation resulted in a better mineralization of organic matter; however, O₃/UV oxidation achieved a better enhancement of the biodegradability. Furthermore, similar degradation of halogenated compounds were observed for both oxidation processes.     

Grafting of titanium dioxide microspheres with a temperature‐responsive polymer via surface‐initiated atom transfer radical polymerization without the use of silane coupling agents

Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO₂ microparticles via a straightforward controlled surface‐initiated polymerization method.     

Effective reduction of AlN defect luminescence by fluorine implantation

We report on the effective reduction of AlN host lattice defect cathodoluminescence by high dose ion implantation of light elements such as fluorine as well as chlorine and neon with peak concentrations of 1 at.%. In order to distinguish between luminescence suppression in the visible to luminescence quenching due to radiation damage, all samples were additionally implanted with europium at fluences of 1 · 10¹³ ions/cm². After annealing the samples at 1373 K under vacuum conditions cathodoluminescence spectra were recorded at room temperature (300 K) and at cryogenic temperature (12 K). These investigations reveal that different light ion species have different influences on the defect luminescence of the AlN host lattice which is likely due to selective passivation of these defects. The best ratio of defect luminescence suppression to radiation damage induced luminescence quenching is achieved in the case of fluorine co-doping.     

Catalytic Materials for High-Temperature Combustion

Catalytic combustion, as an alternative to conventional thermal combustion, has received considerable attention during the past decade. Research efforts have been promoted by the need to meet governmental demands concerning pollution and the wish to use energy sources more efficiently. The two main advantages offered by catalytic combustors over flame combustors apply to these goals:

1. Catalytic combustion can be carried out over a wide range of fuel concentrations in air and at low temperatures.
2. These low temperatures result in attaining NO, emission levels substantially lower than possible with conventional combustors.

     

Design,Synthesis, and Characterization of Macrocyclic Inhibitors of the Proprotein Convertase Furin

The activation of viral glycoproteins by the host protease furin is an essential step in the replication of numerous pathogenic viruses. Thus, effective inhibitors of furin could serve as broad-spectrum antiviral drugs. A crystal structure of an inhibitory hexapeptide derivative in complex with furin served as template for the rational design of various types of new cyclic inhibitors. Most of the prepared derivatives are relatively potent furin inhibitors with inhibition constants in the low nanomolar or even sub-nanomolar range. For seven derivatives the crystal structures in complex with furin could be determined. In three complexes, electron density was found for the entire inhibitor. In the other cases the structures could be determined only for the P6/P5-P1 segments, which directly interact with furin. The cyclic derivatives together with two non-cyclic reference compounds were tested as inhibitors of the proteolytic activation and replication of respiratory syncytial virus in cells. Significant antiviral activity was found for both linear reference inhibitors, whereas a negligible efficacy was determined for the cyclic derivatives.     

Influence of Stress and Chemical Homogeneity on Dielectric Properties of BaTi0.9Zr0.1O3

The influence of mechanical stress and chemical homogeneity on the permittivity of BaTi_0.9Zr_0.1O₃ ceramics prepared from mixed-oxide and hydrothermal powders was studied. To reduce stress, liquid-phase sintering was applied in conjunction with a low heating rate to stimulate the formation of large grains. The influence of chemical homogeneity was studied by variations in sintering temperatures and times. For both types of ceramics, the dielectric constant at the Curie temperature was influenced by both factors, but to a different extent. In the mixed oxide ceramic, chemical homogeneity played a more prominent role, while internal stress appeared to exert a larger influence in the hydrothermal ceramics. The dielectric constant at the Curie temperature could be increased by 5%–10% by an annealing treatment at 200°C, followed by slow cooling.