Photoinitiated cationic oligomerization of terminal and internal epoxides

The iodonium salt‐catalyzed, photoinduced cationic oligomerization of terminal and internal monoepoxides from oleochemical as well as the petrochemical origin was studied. The ring‐opening of terminal epoxides (1,2‐octene oxide, phenyl glycidyl ether, 9,10‐epoxy decanoic acid methyl ester and 10,11‐epoxy undecanoic acid methyl ester) predominantly led to macrocyclic oligoethers (M_n = 650—1,100 g/mol) via backbiting in quantitative yields. Mixtures of cyclic and bishydroxy‐terminated oligoethers (M_n = 1,050—1,500 g/mol) were achieved by the conversion of internal epoxides (7,8‐tetradecene oxide and cis‐9,10‐epoxy octadecanoic acid methyl ester) in yields of 80—95%. Macrocyclization was completely suppressed by addition of 20 mol‐% water or ethylene glycol receiving diol‐oligoethers for potential application as soft segments for polyurethanes with molecular weights of approximately 1,300 g/mol.     

Haltung zur Erhaltung

Attitude towards preservation Hydraulic structures have always been designed as long-lasting infrastructure assets, which is also reflected in current codes for new structures. Climate change and climate protection confirm the need for durable structures with the longest possible service life. Existing hydraulic structures should fulfil this objective and be maintained for as long as is technically, operationally, economically and ecologically feasible. Maintenance should not only ensure that the planned service life is achieved, but should also extend the service life. This can be achieved, for example, through more realistic structural verifications of the structures, through maintenance and through optimized refurbishment.     

Molecular Basis of Endometriosis and Endometrial Cancer: Current Knowledge and Future Perspectives

The human endometrium is a unique tissue undergoing important changes through the menstrual cycle. Under the exposure of different risk factors in a woman’s lifetime, normal endometrial tissue can give rise to multiple pathologic conditions, including endometriosis and endometrial cancer. Etiology and pathophysiologic changes behind such conditions remain largely unclear. This review summarizes the current knowledge of the pathophysiology of endometriosis and its potential role in the development of endometrial cancer from a molecular perspective. A better understanding of the molecular basis of endometriosis and its role in the development of endometrial pathology will improve the approach to clinical management.     

Laser structuring of crystalline silicon thin-film solar cells on opaque foreign substrates

Crystalline silicon thin-film solar cells were fabricated on graphite substrates. A laser ablation process was developed for edge isolation of the thin-film cells. The shunt resistance was comparable to otherwise identical cells isolated by plasma etching, while the reproducibility of the laser isolation process was higher. The solar cells were characterized by current-voltage and light beam induced current measurements (LBiC). No interference was detected along the ablated edges. Spatial variations of the minority carrier lifetime are attributed to the grain structure of the seeding layer obtained by the zone melting recrystallization (ZMR).     

Inhibitors of inducible NO synthase expression: total synthesis of (S)-curvularin and its ring homologues

(S)-Curvularin and its 13-, 14-, and 16-membered lactone homologues were synthesized through a uniform strategy in which a Kochi oxidative decarboxylation and ring-closing metathesis reactions constitute the key processes. In the evaluation of the anti-inflammatory effects of the synthesized compounds in assays using cells stably transfected with a human iNOS promoter-luciferase reporter gene construct, the 14- and 16-membered homologues showed a slightly higher inhibitory effect towards iNOS promoter activity than curvularin itself. However, the larger ring homologues also exhibited higher cytotoxicity, manifest in downregulated eNOS promoter activity. In contrast, the di-O-acetyl and 4-chloro derivatives of (S)-curvularin showed higher inhibitory efficiency towards induction of the iNOS promoter and less negative effect on eNOS promoter activity than curvularin.     

Chlor-alkali electrolysis with oxygen depolarized cathodes: history,present status and future prospects

The historical development, current status and future prospects of chlor-alkali electrolysis with oxygen depolarized cathodes (ODCs) are summarized. Over the last decades, membrane chlor-alkali technology has been optimized to such an extent that no substantial reduction of the energy demand can be expected from further process modifications. However, replacement of the hydrogen evolving cathodes in the classical membrane cells by ODCs allows for reduction of the cell voltage and correspondingly the energy consumption of up to 30%. This replacement requires the development of appropriate cathode materials and novel electrolysis cell designs. Due to their superior long-term stability, ODCs based on silver catalysts are very promising for oxygen reduction in concentrated NaOH solutions. Finite-gap falling film cells appear to be the technically most mature design among the several ODC electrolysis cells that have been investigated.