Pfropfversuche an Cellulose mit Siloxanen

Zusammenfassung Die an der Cellulose schon vielfach erprobte Pfropfung mit polymerisierbaren olefinischen Monomeren, wie Styrol, Acrylnitril, Methylacrylat, Vinylchlorid u. a., wurde hier mit polykondensierbaren Siliciumverbindungen versucht. Die gewonnenen Pfropfprodukte, die technisch als Siliconcellulosen bezeichnet werden könnten, sind einer kurzen Prüfung in bezug auf ihre Hydrophobie und ihren Siloxangehalt unterzogen worden.Mit 6 AbbildungenHerrn Prof. Dr.Fritz Wessely zu seinem 70. Geburtstag mit den herzlichsten Glückwünschen gewidmet.     

Thermodynamics of ionization of some substituted 4-methyl-thioanilines

Ionization constants of chloro, iodo and nitro substituted 4-methyl-thioanilines were determined over the range 30° to 50° using a spectro-photometric method. The results were analyzed in terms of the Harned-Robinson equation and values of heat, free energy and entropy of ionization were calculated. The free energies are additive, except in the case of 3, 5-diiodo-4-methylthioaniline, while the heats and the entropies are not.     

A robust and fast method of sampling and analysis of delta13C of dissolved inorganic carbon in ground waters

The stable carbon isotopic composition of dissolved inorganic carbon (delta13C(DIC)) is traditionally determined using either direct precipitation or gas evolution methods in conjunction with offline gas preparation and measurement in a dual-inlet isotope ratio mass spectrometer. A gas evolution method based on continuous-flow technology is described here, which is easy to use and robust. Water samples (100-1500 microl depending on the carbonate alkalinity) are injected into He-filled autosampler vials in the field and analysed on an automated continuous-flow gas preparation system interfaced to an isotope ratio mass spectrometer. Sample analysis time including online preparation is 10 min and overall precision is 0.1 per thousand. This method is thus fast and can easily be automated for handling large sample batches.     

Soliton mode-locked Er:Yb:glass laser

We report on a simple diode-pumped passively mode-locked Er:Yb:glass laser generating transform-limited 1536-nm solitons of 255-fs duration with a repetition rate of 50 MHz and average power of 58 mW. We also discuss timing jitter and the trade-off between short pulses and high output power in these lasers.