Composite right/left handed artificial transmission line structures in CMOS for controlled insertion phase at 30 GHz

Two CMOS integrated circuits are presented that utilize metamaterial composite right/left handed (CRLH) transmission lines (TLs) for zero insertion phase at 30 GHz. Specifically, 2 and 3 unit cell structures are presented with controlled insertion phase that is achieved by cascading lumped element capacitors and spiral inductors in an LC network configuration defining the TL unit cells. Furthermore, the fixed TL structures suggest the possibility of zero, advanced or delayed insertion phases by element variation, or by the use of simple active components. Simulation and measured results are in good agreement with CRLH TL theory, and display a linear insertion phase and flat group delay values that are dependent on the number of unit cells with an insertion loss of ～0.8 dB per cell. These findings suggest that such high speed CRLH TLs structures can be implemented for linear array feeding networks and compact antenna designs in CMOS at millimeter wave frequencies. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009.     

Synthesis of (all‐rac)‐α‐Tocopherol Using Fluorinated NH‐Acidic Catalysts

The synthesis of (all‐rac)‐α‐tocopherol starting from trimethylhydroquinone and isophytol using fluorinated NH‐acidic catalysts is described. Scope and limitations of this type of catalysts are discussed. Advantages of this new procedure are high yield and selectivity, no waste problem and mild reaction conditions. Best results in the synthesis of (all‐rac)‐α‐tocopherol (94% yield) using NH‐acidic compounds are obtained in polar solvents. The used catalyst could be recovered.     

Microstructural characterization of propylene–butene-1 copolymer using temperature rising elution fractionation

Propylene–butene-1 copolymer (PBC) prepared with a titanium catalyst system was fractionated by temperature rising elution fractionation (TREF) over a temperature range of 5–80°C. PBC was shown to have a wide composition distribution ranging between 12–47 mol % of butene-1. Most of the fractions showed nearly the same crystallinity regardless of the butene-1 content. However, the solubility of the crystalline parts, which turned out to be the driving force for the fractionation, varied over the butene-1 content. Evidence that PBC shows isomorphism was obtained by the analysis of fractionated polymers, using ¹³C nuclear magnetic resonance spectrometry, X-ray diffraction, differential scanning calorimetry, and gel permeation chromatography. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1493–1501, 1998     

Erythrocytes Prevent Degradation of Carnosine by Human Serum Carnosinase

The naturally occurring dipeptide carnosine (β-alanyl-l-histidine) has beneficial effects in different diseases. It is also frequently used as a food supplement to improve exercise performance and because of its anti-aging effects. Nevertheless, after oral ingestion, the dipeptide is not detectable in human serum because of rapid degradation by serum carnosinase. At the same time, intact carnosine is excreted in urine up to five hours after intake. Therefore, an unknown compartment protecting the dipeptide from degradation has long been hypothesized. Considering that erythrocytes may constitute this compartment, we investigated the uptake and intracellular amounts of carnosine in human erythrocytes cultivated in the presence of the dipeptide and human serum using liquid chromatography–mass spectrometry. In addition, we studied carnosine’s effect on ATP production in red blood cells and on their response to oxidative stress. Our experiments revealed uptake of carnosine into erythrocytes and protection from carnosinase degradation. In addition, no negative effect on ATP production or defense against oxidative stress was observed. In conclusion, our results for the first time demonstrate that erythrocytes can take up carnosine, and, most importantly, thereby prevent its degradation by human serum carnosinase.