Some European satellite-antenna developments and trends

The environment, as well as the mass and available power limitations specific to space missions, add special constraints. These lead to the use of exotic low-mass, high-stability materials, with advanced mechanical and thermal designs. Also, antenna front ends must be tailored for optimum efficiency and power handling. Researchers and engineers in universities, research institutes, and industrial laboratories, from the 14 member states of the European Space Agency (ESA), together with staff from the European Space Agency's Technology Centre (ESTEC) antenna section and from project teams, have studied and developed software-modeling tools, critical reflector and array technologies, novel antenna architectures, and special measurement techniques to cope with these requirements. This paper presents an overview of some of the latest antenna-design tools and technology developments, supported by ESA for space applications. The following topics are covered reflectors, feed systems, and direct-radiating arrays. Some trends and developments in space antenna requirements and technologies are outlined     

Phlegmon of the stomach simulating a perforated ulcer

A new family of cytochrome P450 enzymes, CYP26, has been cloned and characterized in zebra fish, human, and mouse tissues. CYP26 displays specificity toward retinoic acid and it may function as an important regulator or differentiation and a possible modulator of disease states by controlling retinoid concentration and homeostasis.     

Enzymatic and molecular diagnosis of Gaucher disease

Advances in the knowledge of the molecular genetics of Gaucher disease has made diagnosis more certain. Carrier detection in kindreds in which the responsible mutation has been defined is completely reliable now. Coupled with enzymatic assays, the diagnostic capabilities are greater than before. Use of these methods provides important information to individuals at risk and allows them to make critical decisions. The new, simplified methods reviewed in this article permit the molecular diagnosis of the disease and carrier stage of large numbers of samples within 1 week.     

Characterization of Linoleum. Part 1: Measurement of Volatile Organic Compounds by use of the Field and Laboratory Emission Cell, “FLEC”⋆

The volatile organic compounds (VOCs) emitted from 12 linoleum samples were measured by use of the “Field and Laboratory Emission Cell” (FLEC) with sampling on Tenax TA followed by thermal desorbtion and GC/FID or GC/MS analysis. Major VOCs were alkanals, alkenals and fatty acids. The emissions were measured after 24 h in FLEC and again after one month's storage in a well ventilated room. The emission profiles of hexanal, nonanal and propanoic acid were modeled for four linoleum samples using a new exponential diffusion model. The time required to reach 50% of the odor threshold concentrations in a standard room was from 113 to 2296 hours. The applicability of the diffusion model for modeling long-term emission needs to be further evaluated considering possible continuous oxidative emission.