Advanced undergraduate experiments in vacuum physics and mass spectrometry

A comprehensive high‐vacuum system has been set up and operated in an advanced undergraduate laboratory for students majoring in physics and microelectronics. The aim of the experiment is to provide the students with both practical experience and basic theoretical understanding of the production and measurement of low pressures. The students measure the pumping speed of a rotary forepump and of an oil diffusion pump, as a function of pressure, using procedures adopted by the AVS. A hot‐cathode ionization gauge and a thermocouple gauge are calibrated against a McLeod (absolute) manometer for several gases. The compositions of ambient air, of an isotopic mixture of neon, and of the residual gases in an oil‐diffusion‐pumped system are determined with the aid of a mass spectrometer. The influence of a liquid‐nitrogen‐cooled surface is assessed. Helium leak detection is demonstrated, and the response and sensitivity of the mass spectrometer as a leak detector are evaluated

SYNALLAGMA AND FREEDOM OF CONTRACT - The Concept of Reciprocity and Fairness in Contracts from the Historical and Law and Economics Perspective

The problem of commutative justice has been widely analysed by the contemporary doctrine of civil law. Simultaneously there is a profound debate about the meaning of commutative justice and equivalence in exchange within the sphere of moral philosophy. All these issues seem to concern the problem of interdependence between parties. Such interdependence is called synallagma or the principle of synallagma. In this paper I would like to present the concept of synallagma in civil law and in philosophy of law. Since the dispute in both disciplines seems to be unresolved and inconclusive, I would like to present the two economic theories concerning synallagma as the strategic interaction between agents. The most appropriate tool to be implemented seems to be the game theory. In conclusion I would like to address the question whether substantial and objective equivalence in contracts is possible or under which conditions it is meaningful.

Pulsed electron beam induced recrystallization and damage in GaAs

Single-pulse electron-beam irradiations of 300-keV 10^(15)Kr+/cm^2 or 300-keV 3×10^(12)Se+/cm^2 implanted layers in unencapsulated GaAs are studied as a function of the electron beam fluence. The electron beam pulse had a mean electron energy of ~-20 keV and a time duration of ~-10^(–7) s. Analyses by means of MeV He + channeling and TEM show the existence of narrow fluence window (0.4–0.7 J/cm^2) within which amorphous layers can be sucessfully recrystallized, presumably in the liquid phase regime. Too high a fluence produces extensive deep damage and loss of As

Steady-state thermally annealed GaAs with room-temperature-implanted Si

Semi-insulating Cr-doped single-crystal GaAs samples were implanted at room temperature with 300-keV Si ions in the dose range of (0.17–2.0)×1015 cm–2 and were subsequently steady-state annealed at 900 and 950°C for 30 min in a H2 ambient with a Si3N4 coating. Differential Hall measurements showed that an upper threshold of about 2×1018/cm3 exists for the free-electron concentration. The as-implanted atomic-Si profile measured by SIMS follows the theoretical prediction, but is altered during annealing. The Cr distribution also changes, and a band of dislocation loops ~2–3 kÅ wide is revealed by cross-sectional TEM at a mean depth of Rp~3 kÅ. Incomplete electrical activation of the Si is shown to be the primary cause for the effect

The thickness of a liquid layer on the free surface of ice as obtained from computer simulation

Molecular dynamic simulations were performed for ice Ih with a free surface by using four water models, SPC/E, TIP4P, TIP4P/Ice and TIP4P/2005. The behavior of the basal plane, the primary prismatic plane and of the secondary prismatic plane when exposed to vacuum was analyzed. We observe the formation of a thin liquid layer at the ice surface at temperatures below the melting point for all models and the three planes considered. For a given plane it was found that the thickness of a liquid layer was similar for different water models, when the comparison is made at the same undercooling with respect to the melting point of the model. The liquid layer thickness is found to increase with temperature. For a fixed temperature it was found that the thickness of the liquid layer decreases in the following order: the basal plane, the primary prismatic plane, and the secondary prismatic plane. For the TIP4P/Ice model, a model reproducing the experimental value of the melting temperature of ice, the first clear indication of the formation of a liquid layer appears at about -100 Celsius for the basal plane, at about -80 Celsius for the primary prismatic plane and at about -70 Celsius for the secondary prismatic plane.Comment: 41 pages and 13 figure

Electrical properties of silicon-implanted furnace-annealed silicon-on-sapphire devices

The crystalline quality of s.o.s. layers can be improved near the silicon-sapphire interface by silicon implantation followed by recrystallisation. Device performance on such layers is markedly improved as to n-channel m.o.s.t. noise and leakage current, reverse diode current and lateral bipolar transistor gain. Minority-carrier lifetimes up to 50 ns are deduced

Melt blending and characterization of carbon nanoparticles-filled thermoplastic polyurethane elastomers

In this work, thermoplastic polyurethane (TPU) elastomers reinforced with carbon nanosized particles were produced by a special melt blending technique. A TPU was melt blended with high-structured carbon black and carbon nanofibres (1 wt%). A miniature asymmetric batch mixer, which applies high shear levels to the melt, ensured good particles dispersion. The TPU material systems were then thoroughly characterized using thermogravimetric analysis, differential scanning calorimetry, tensile mechanical testing, electrical resistance measurements and flammability tests. The different nanofillers exhibited different influences on the TPU properties, these materials featuring interesting and improved multifunctional behaviours, with high propensity for large deformation sensors applications.This work was supported by FCT – Portuguese Foundation for Science and Technology through projects NANOSens – PTDC/CTM/73465/2006

Long-term clinical and experimental/surface analytical studies of carbon/carbon maxillofacial implants

BACKGROUND:Over the past 30-40years, various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). The aim of this study is to present the long-term clinical results of carbon/carbon implants, and the results of the scanning electron microscope and energy dispersive spectrometer investigation of an implant retrieved from the human body after 8years.METHODS:Mandibular reconstruction (8-10years ago) was performed with pure (99.99%) carbon implants in 16 patients (10 malignant tumours, 4 large cystic lesions and 2 augmentative processes). The long-term effect of the human body on the carbon/carbon implant was investigated by comparing the structure, the surface morphology and the composition of an implant retrieved after 8years to a sterilized, but not implanted one.RESULTS:Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. During the long-term follow-up, plate fracture, loosening of the screws, infection or inflammations around the carbon/carbon implants were not observed. The thickness of the carbon fibres constituting the implants did not change during the 8-year period, the surface of the implant retrieved was covered with a thin surface layer not present on the unimplanted implant. The composition of this layer is identical to the composition of the underlying carbon fibres. Residual soft tissue penetrating the bulk material between the carbon fibre bunches was found on the retrieved implant indicating the importance of the surface morphology in tissue growth and adhering implants.CONCLUSIONS:The surface morphology and the structure were not changed after 8years. The two main components of the implant retrieved from the human body are still carbon and oxygen, but the amount of oxygen is 3-4 times higher than on the surface of the reference implant, which can be attributed to the oxidative effect of the human body, consequently in the integration and biocompatibility of the implant. The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates

The European Monetary Union within the Coasean Transactional Framework – Some Remarks on Legal Remedies as an Instrument of Harmonization of the Europe

The paper concentrates on the possibility of indirect harmonization of compensation awarded for the infringement of the rights protected by the EC law. Within the literature the problem of the influence of the European monetary integration upon the legal harmonization has not been analyzed so far. In the present paper the theory of transactional framework (Calabresi & Melamed 1972, Ayres 2005) has been applied in order to analyze the potential economic consequences of the operation of the multilevel judicial governance structure which has been created in the European Union. The functional framework of the multilevel European judicial governance (Maduro, 2003; Petersmann, 2008) is thus to be analyzed from the perspective of the economic consequences of the European monetary integration (Rogoff, 1996; Rose, 2000)

The Coase Theorem and Philosophical Foundations of Law&Economics

In this paper I will claim that methodology of law and economics should be changed from adopting economic analysis of law, namely implementing price theory andwelfare economics (economization of law) to the scientific efforts aiming at an inter-disciplinary project embracing law and economics as well as jurisprudence. Thebasis for such a project is purported by the Coase theorem, but may also be found inwritings of Hayek and old institutionalists”, such as Veblen, Hale and Commons.The purpose of this paper is thus twofold: firstly, to present briefly the most power-ful and popular version of law and economics being at the same time influential legal theory- the Chicago school. Secondly, to analyze the existing alternative approaches to economics of law, related to Austrian school (Hayek), „old institutional” economics (Commons) and transaction cost economics (Coase)