Flying solo and solar to Mars

This paper describes the work done by the Autonomous Systems Lab of Ecole Polytechnique Federale de Lausanne (EPFL) on the global design of an unmanned solar airplane that can fly continuously over days and night. Part of the Sky-Sailor Project, a first prototype was designed and demonstrated to have very good flight characteristics. The prototype achieved an autonomous flight of five hours with its energy only from the sun. A lightweight control and navigation system was also designed for the aircraft.     

Amplification of c-myc proto-oncogene in primary tumors, metastases and blood leukocytes of patients with ovarian cancer

The structure of DNA sequences homologous to the viral myc oncogene from ovarian tumours, intact tissues and the same patients peripheral blood leukocytes has been studied. The Southern blot analysis of malignant tumour DNA reveals amplification of c-myc protooncogene of 3 from 11 patients. Metastases DNAs of two from those patients also contain multiple copies of c-myc. No myc gene amplification has been detected in 6 examined benign ovarian tumours. The presence of extra copies of myc-related sequences has been shown in two from three DNA samples from peripheral blood leukocytes of patients with ovarian cancer.     

On the mechanisms of adenosine induced pulmonary vasoconstriction in rats

The effect of adenosine on pulmonary vessels was studied in isolated perfused rat lungs. Drugs were administered intra-arterially in a fixed volume of 0.1 ml Krebs solution as bolus injections. Adenosine responses were obtained before and 10 min after drug injections. When applied in logarithmically increasing doses (1-100 micrograms/ml), adenosine caused dose-dependent increases in pulmonary perfusion pressure (e.g. pulmonary vasoconstriction) which were readily reversible. Challenging adenosine with quinidine, dihydroergocristine and cyproheptadine (2 micrograms/ml each) did not significantly alter adenosine responses. Pretreatment of lungs with 0.5 mM theophylline, 10 micrograms/ml indomethacin, 30 micrograms/ml tebokan (a PAF antagonist) or 1 microgram/ml methylene blue for 10 min, however, antagonized the vasoconstrictor effect of the drug significantly. From these experiments, it was concluded that the mechanisms underlying the pulmonary vasoconstrictor action of adenosine are complex, and that both types of purinoceptors, prostaglandins, PAF and other vascular endothelial hormones might be involved.     

Annular slot-coupled dielectric resonator antenna

An annular slot-coupled dielectric resonator antenna is investigated experimentally. As compared with the previous rectangular-slot version, the new configuration offers a much wider bandwidth of 18%. The return loss, radiation patterns, and antenna gain of the configuration have been measured and are discussed     

Thermochemical investigation of binary liquid mixtures in glass-forming oxide systems

Methods and equipment successfully employed in high- temperature calorimetry to measure partial and integral enthalpies of mixing in liquid oxide systems are reviewed with special attention given to the drop-mixing method. This technique has been used to measure enthalpies of mixing in binary liq-uid mixtures composed of network forming oxides (e.g. SiO₂) and network modifying oxides (e.g. Na₂O). Results for the systems Na₂O-SiO₂ and Na₂O- B₂O₃ are presented graphically. Entropies of mixing were estimated by combining enthalpies with available data on Gibbs energies of mixing. Prominent thermochemical features of glass-forming oxide melts are pointed out. The observed thermodynamic behavior is discussed in relation to its structural basis.     

Study of the Polymorphism of Saturated Monoacid Triglycerides II: Polymorphic Behaviour of a 50/50 Mixture of Tripalmitin and Tristearin

The polymorphic behaviour of a 50/50 blend of tripalmitin and tristearin has been investigated in detail using differential scanning calorimetry and X-ray diffraction. The blend is characterized by a greater tendency to β'-crystallization as compared to the pure triglycerides. Tripalmitin and tristearin, when mixed in a 1:1 ratio, are miscible in both the α-form and the β-form. In the β-form, however, demixing occurs, resulting in a 2-phase solid state. The characteristics of the α-form are considerably affected by the crystallization conditions, due to the formation of concentration gradients during crystallization. The β'-form can be obtained from the melt as well as via recrystallization of the α-form, and is characterized by a much higher stability as compared to the pure triglycerides. The X-ray diffraction data of the β'-form of the blend reveal a β₁-crystal structure. The β'-form of the pure triglycerides, however, is characterized by a β'₂-crystal structure. On the basis of the present data, however, no clear structural distinction can be made between β'₂ and β'₁.     

Heterogeneous flux formation in plasma pulse deposition

Conclusions Measurements have been made on the trends in the formation of heterogeneous plasma flows in a coaxial plasma accelerator as affected by the design and technological parameters.There are large spreads in the thermokinetic and concentration parameters when the powder is supplied to a cylindrical tube in the accelerator. The optimum heterogeneous-flow organization is obtained in a new plasma accelerator design that provides a uniform particle distribution in velocity and concentration in the cross section of the plasma jet and compression of the plasma cloud along the jet. The powder use factor is increased by a factor 1.3-1.5.An Ar+H₂ mixture as the plasma-forming gas gives high-grade homogeneous coatings with low porosity.Translated from Fiziko-Khimicheskaya Mekhanika Materialov, Vol. 27, No. 4, pp. 60–66, July–August, 1991.