Thermoanalytical Screening of Nitrogen-Rich Substances

The thermal decomposition behaviour of approx. 60 nitrogen-rich substances on the basis of tetrazole and tetrazine structures was investigated by thermoanalytical methods. Decomposition mechanisms initiated by ring opening of the heterocycles could be established. Substituent effects on the exothermic decomposition characteristics of nitrogen-rich compounds are demonstrated.     

Synthesis of α-fucosyl glycosides and disaccharides using 4-methoxybenzyl (Mpm) protected fucosyl donors

The 4-methoxybenzyl (Mpm) group removable by selective oxidation was applied as a nonneighbouring-group-active protection of fucose hydroxy functions in the stereoselective synthesis of α-fucosides of acceptors containing double bonds sensitive to hydrogenation. With this aim, the synthesis of the α-fucosyl chloride ( 4 ) carrying the acidsensitive Mpm protection was elaborated.     

Burning Behaviour of Gas Generators with High Boron Content

Gas generators with high boron content of interest for ducted rockets were prepared and characterized. The parameters tested were:

• – combustion residue
• – pressure exponent
• – flow and temperature of the ejected boron particles
• – mechanical properties.

The results of the experments (optical bomb, high speed camera, two-color pyrometer, thermal analysis, tensile test) are presented and discussed.     

Therapeutic Treatments for Osteoporosis—Which Combination of Pills Is the Best among the Bad?

Osteoporosis is a chronical, systemic skeletal disorder characterized by an increase in bone resorption, which leads to reduced bone density. The reduction in bone mineral density and therefore low bone mass results in an increased risk of fractures. Osteoporosis is caused by an imbalance in the normally strictly regulated bone homeostasis. This imbalance is caused by overactive bone-resorbing osteoclasts, while bone-synthesizing osteoblasts do not compensate for this. In this review, the mechanism is presented, underlined by in vitro and animal models to investigate this imbalance as well as the current status of clinical trials. Furthermore, new therapeutic strategies for osteoporosis are presented, such as anabolic treatments and catabolic treatments and treatments using biomaterials and biomolecules. Another focus is on new combination therapies with multiple drugs which are currently considered more beneficial for the treatment of osteoporosis than monotherapies. Taken together, this review starts with an overview and ends with the newest approaches for osteoporosis therapies and a future perspective not presented so far.     

Stärken und ihre Hydrolysate als pharmazeutische Hilfsstoffe. Teil 1: Früherer Stand und Entwicklungstendenzen

Starches and Their Hydrolysis Products as Pharmaceutical Adjuvants. Part I: Review on the Early State and Tendencies of Developments. Beginning with a comprehensive survey on the former state of application of starches until the seventies the general tendencies of the development of the material basis as well as important applications are shown. Points of interest are focused on the structure-properties relations of pharmaceutical adjuvants as the essential basis for considering selected alpha-glucans in their present and future roles as carriers and stabilizers for pharmaceutical agents and plasmaexpanders.     

Mechanisms of fatigue in short glass fiber reinforced polyamide 6

An adaptation to existing failure models for fatigue fracture of short fiber reinforced thermoplastics is presented, based on results using some new experimental methods. These results lead to the following conclusion: Cracks in polyamide remain bridged (by plastically drawn matrix material and/or fibers) until just before final fracture. Important is the conditioning of the polyamide: conditioned to equilibrium water content, this mechanism occurs, but not when it is dry as molded. Fatigue damage measurements were done on thin foils cut from the fatigued specimen. When tensile tested, these foils show a change in both strength and fracture strain after fatigue. Further observations during the experiments and SEM fractography strengthen the conviction that fatigue damage initiates and grows in the form of bridged cracks. A correlation between tensile strength and fatigue strength was found; the degree of fiber alignment has a similar effect on both tensile and fatigue properties.     

On sliding friction and wear of polyetheretherketone (PEEK) composites at elevated temperatures

The friction and wear behaviour of polyetheretherketone (PEEK) composites, incorporating different amounts of short carbon fibres with different surface treatments, was studied under dry sliding conditions against smooth steel on a pin-on-disc apparatus at different temperatures. Wear of the composites was reduced considerably in all cases, but, whatever the surface treatment, wear increased with increasing temperature for all proportions off fibres. For minimum friction coefficient there was an optimum proportion of fibre volume fraction of about 10 vol.%. The effect of the fibre surface treatment was not significant for the tribological behaviour of the PEEK composites. To predict wear performance, a wear model proposed by Friedrich and Voss seemed to work properly, and, furthermore, a friction model was developed to predict the friction behaviour of PEEK composites with short carbon fibres.     

Die Acyloin-Kondensation von 1,2-Diacyloxyethanen; Gezielte Darstellung unsymmetrisch substituierter 1,2-Bis-(trimethylsiloxy)ethene

Acyloin Condensation of 1,2-Diacyloxyethanes; Directed Synthesis of Unsymmetrically Substituted 1,2-Bis-(trimethylsiloxy)ethenes A synthesis specifically directed to unsymmetrically substituted 1,2-bis-(trimethylsiloxy)ethenes ( 2a–d ), precursors of the corresponding acyloins, was accomplished by intramolecular acyloin condensation of the unsymmetrical 1,2-diacyloxyethanes ( 1a–d ) with sodium in toluene/chlorotrimethylsilane.