Miniaturized high-temperature superconductor microstrip patchantenna

Experimental as well as computational results are presented for 2.4 GHz microstrip antennas which are miniaturized (total length, 6 mm) by both a new, stepped impedance patch shape and a relatively high substrate permittivity. The antennas investigated were fabricated from YBa₂Cu₃O_7-δ thin films epitaxially grown on single-crystalline LaAlO₃ substrates by pulsed excimer laser ablation or by high-pressure oxygen DC sputtering and, for comparison, from copper on the same substrate material. It is shown that the radiation efficiency of this antenna structure is only about 1% to 6% for copper at 77 K but is increased to values between 35% and 65% for HTS films. From experimental investigations of the power dependence of the antenna gain at 77 K, nonlinearities, especially a sharp drop at a current density of about 2×10⁶ A/cm², were observed     

Influence of trisamide-based additives on the morphological and mechanical properties of isotactic polypropylene

The influence of two different trisamide-based additives on the morphological and mechanical behavior of isotactic polypropylene (PP) is investigated. Morphological investigations by wide-angle X-ray scattering (WAXS) show that only 0.04 wt.-% of one of the additives is enough to induce 80% beta modification in the crystalline part of the polymer. The materials are investigated with quasistatic (tensile testing) as well as short-time dynamic (Charpy impact strength) methods and for the first time fatigue crack growth measurements are performed on alpha- and beta-nucleated PP. In all cases a much higher toughness of the material containing the beta-nucleating agent (beta NA) can be observed. The crack growth propagation rate is one order of magnitude smaller with the use of the beta-nucleating agent compared to the alpha polymer. Scanning electron microscopy (SEM) pictures are used to support the correlation of the mechanical behavior with the morphological changes.     

Investigation on Shot‐Cast Mixes for Blast Furnace Relining

For relining the blast furnaces at the Salzgitter Flachstahl GmbH (SZFG) shot‐cast refractory concretes were used in the shaft. The degradation of refractories used in this part of the furnaces, whether caused by the action of mechanical impact, vaporized melt constituents, products of fuel and coke combustion, or by batch dusts and vapours, can normally only be assessed after a campaign when the furnace is partially or completely disassembled. Thus, tests for investigation of the materials properties and to predict the behaviour and possible degradation on small laboratory specimens exposed to accelerated working conditions are needed. The current testing procedures for refractory concretes used for relining the shafts of the blast furnaces at the SZFG and the test results are expressed in this publication.     

Long-term effects of lifestyle changes on well-being and cardiac variables among coronary heart disease patients.

Objective: To focus on psychological well-being in the Lifestyle Heart Trial (LHT), an intensive lifestyle intervention including diet, exercise, stress management, and group support that previously demonstrated maintenance of comprehensive lifestyle changes and reversal of coronary artery stenosis at 1 and 5 years. Design and Main Outcome Measures: The LHT was a randomized controlled trial using an invitational design. The authors compared psychological distress, anger, hostility, and perceived social support by group (intervention group, n = 28; control group, n = 20) and time (baseline, 1 year, 5 years) and examined the relationships of lifestyle changes to cardiac variables. Results: Reductions in psychological distress and hostility in the experimental group (compared with controls) were observed after 1 year (p