Preparation of graded-index optical glass fibres in the alkali germanosilicate system

Multicomponent glass fibres with a graded refractive index have been made in the alkali germanosilicate system using the double-crucible method. The index profile is based on Na+ ? K+ ion exchange. Bulk-glass absorption losses of ?10 dB/km at 752 nm have been measured. The present minimum level of fibre attenuation is 35 dB/km.     

Bildung eines Hydroxypyrrols aus Methylglyoxal und Methylammoniumacetat

Zusammenfassung Methylglyoxal reagiert mit Methylammoniumacetat in wäßriger Lösung bei erhöhter Temperatur rasch unter Brdunung. Aus dem Gemisch von Umsetzungsprodukten ist 3-Hydroxy-1,2-dimethyl-5-formyl-pyrrol [1] isolierbar.

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Formation of a hydroxypyrrole from methylglyoxal and methylammoniumacetate.VIII. studies on the maillard reaction

Summary Methylglyoxal rapidly reacts in water solution at increased temperatures with methylammoniumacetate by browning. Out of this mixture 3-hydroxy-1.2-dimethyl-5-formvipyrrole can be isolated.

     

Cre mRNA Is Not Transferred by EVs from Endothelial and Adipose-Derived Stromal/Stem Cells during Vascular Network Formation

Coculture systems employing adipose tissue-derived mesenchymal stromal/stem cells (ASC) and endothelial cells (EC) represent a widely used technique to model vascularization. Within this system, cell–cell communication is crucial for the achievement of functional vascular network formation. Extracellular vesicles (EVs) have recently emerged as key players in cell communication by transferring bioactive molecules between cells. In this study we aimed to address the role of EVs in ASC/EC cocultures by discriminating between cells, which have received functional EV cargo from cells that have not. Therefore, we employed the Cre-loxP system, which is based on donor cells expressing the Cre recombinase, whose mRNA was previously shown to be packaged into EVs and reporter cells containing a construct of floxed dsRed upstream of the eGFP coding sequence. The evaluation of Cre induced color switch in the reporter system via EVs indicated that there is no EV-mediated RNA transmission either between EC themselves or EC and ASC. However, since Cre mRNA was not found present in EVs, it remains unclear if Cre mRNA is generally not packaged into EVs or if EVs are not taken up by the utilized cell types. Our data indicate that this technique may not be applicable to evaluate EV-mediated cell-to-cell communication in an in vitro setting using EC and ASC. Further investigations will require a functional system showing efficient and specific loading of Cre mRNA or protein into EVs.     

Design of experiments for statistical modeling and multi-response optimization of nickel electroplating process

The central composite experimental design and response surface methodology have been employed for statistical modeling and analysis of the results dealing with nickel electroplating process. The empirical models developed in terms of design variables (current density J (A/dm²), temperature T (°C) and pH) have been found statistically adequate to describe the process responses, i.e. cathode efficiency Y (%), coating thickness U (μm), brightness V (%) and hardness W (HV). The graphical representations consisted of 2D contour plots and 3D surface plots have been used for exploring and analysis of response surfaces in order to identify the main, quadratic and interaction effects. The multi-response optimization of nickel electroplating process has been carried out by means of desirability function approach. To this end, a genetic algorithm has been used for mathematical optimization of the multi-response problem. The optimization algorithm has conducted to a set of equivalent solutions named Pareto optimal set. The confirmation runs have been employed in order to make a decision about the optimal solution approved by experiment. Thus, the optimum conditions of nickel electroplating has been defined in this work as J* = 5.35 (A/dm²), T* = 33.44 (°C) and pH* = 6.22 and respectively the responses confirmed by experiment were Y = 79.12 ± 0.18 (%), U = 52.77 ± 0.48 (μm), V = 26.12 ± 0.45 (%) and W = 371.6 ± 1.77 (HV). In such conditions the quality of nickel electroplating deposit was the best one in accordance with experimental results.     

A 1.1-V 270-/spl mu/A mixed-signal hearing aid chip

This paper presents a single-chip mixed-signal IC for a hearing aid system. The IC consumes 270 /spl mu/A of supply current at a 1.1-V battery voltage. The presented circuit and architectural design techniques reduce the total IC power to 297 /spl mu/W, a level where up to 70 days of lifetime is achieved at 10 h/day for a small zinc-air battery. The measured input referred noise for the entire channel is 2.8 /spl mu/Vrms and the average THD in the nominal operating region is 0.02%. The jitter for the on-board ring oscillator is 147 ps rms. The chip area is 12 mm/sup 2/ in a 0.6-/spl mu/m 3.3-V mixed-signal CMOS process.     

Multipurpose single-mode fibre-optic coupling substrate, made with silicon etch and polish technique

Using the silicon etch and polish technique a single-mode fibre is exposed uniformly over up to 13 mm length for evanescent mode coupling. This fibre interaction substrate forms the building block for a wide range of fibre-optic devices proposed here. The performance is illustrated experimentally with the coupler as a basic device.<>     

PHASE TRANSITIONS IN PETROLEUM WAXES DETERMINED BY INFRARED SPECTROSCOPY

In the present paper attempts have been made to study the phase transition temperatures in petroleum waxes by infrared spectroscopy and the resulting data were correlated with phase transition temperatures obtained by differential scanning calorimetry (DSC).     

Studien zur Maillard-Reaktion

Zusammenfassung Nach Untersuchungen vonDiemair undJury (3) entstehen die bei der Maillard-Reaktion auftretenden braunen Produkte durch Umsetzung von Hydroxymethylfurfurol mit Aminosäuren.Zur Klärung der Frage, in welcher Weise Furfurol bzw. Hydroxymethylfurfurol mit Tryptophan oder Tryptophan-haltigen Peptiden reagieren können, haben wir Modell-Reaktionen mit Tryptamin durchgeführt. Dabei erhielten wir die Tetra hydro--earbolin-Derivate6 a und6 b. Tetrahydro--carboline (7 a und8) entstanden auch bei Umsetzungen mit Glycerinaldehyd und Dihydroxyaceton. Ebenso wurde aus Tryptophan und Glycerinaldehyd die Carbonsäure7 b erhalten.Neue Anschr.: Institut für Pharmazie u. Lebensmittelchemie der Universität München.