Analytical chemistry in controlled thermonuclear fusion

The analytical problems arising in the fuel cycle of a fusion reactor have to be discussed separately for the various subsystems of such a reactor. Thus, in the case of plasma exhaust purification, concentration assays of the tritiated impurities must be carried out quickly and, whenever possible, under flow conditions. Conventional methods may be employed for this purpose, such as mass spectrometry, FT-IR spectrometry and laser Raman spectrometry, but they will all have to be adapted to special conditions, especially for online operation.     

Zur Realisierbarkeit der Darstellungen der 3-dimensionalen Drehgruppe

Ohne Zusammenfassung     

Utilisation des accelerateurs en analyse par activation,notamment pour la caracterisation des materiaux purs

The principal means of activation, their potential performances and their special fields of application are reviewed briefly. The possibilities offered by charged particles and gammaphotons regarding the determination of light elements or other impurities in pure materials are surveyed. Examples relatives to the evaluation of boron, carbon, nitrogen, oxygen or fluorine contents in metals (Na, Al, Ti, Ni, Cu, Zr, Mo, Ta, W, Pb, etc.), alloys (PbCuTe, PbSnCd) and semiconductors (Si, AsGa, InP, etc.) are given. For some of these products, the results obtained by nuclear methods are compared with values supplied by other analytical techniques. Once the concentration levels of these impurities fall below 1 μg·g⁻¹, the superiority of the former methods appears clearly.      

Analytical application of the direct observation of nuclear reactions induced by low-energy protons and leading to the emission of γ-photons,which are measured

The yields of the most characteristic photon emissions of the elements Li, Be, B, C, N, O and F were plotted for incident proton energies ranging from 400 keV to 1500 keV. The possibilities offered by the use of this direct observation method to measure the superficial concentrations of these elements are deduced. The sensitivities intrinsically obtainable with our experimental device are given and the practical possibilities of the method are discussed, allowance being made for the simultaneous presence of several of the above elements.     

Particle behavior in aesthetic field theory

We discuss the structure of a particle system obtained in “aesthetic” field theory and study the evolution of this system in time. We find the particle system to have more structure than particles found by other authors investigating particlelike behavior in nonlinear field theories. Our particle system has a maximum center in proximity to a minimum center. Thus, we can interpret our system as being constructed of two bodies. We find that the maximum center and the minimum center move in straight lines, to computer accuracy. Thus, we have not found any nontrivial force laws. This suggests that the situation with respect to basic principles be kept fluid. So far as we know, we are the first investigators to study the trajectories of a two-body system which arises as a consequence of nonlinear field equations.     

Advances in photolithographically fabricated ENFET membranes

A photolithographically fabricated membrane for enzyme immobilisation based on an Ion Sensitive Field Effect Transistor (ISFET) is described. The preparation of an Enzyme-FET (ENFET) containing urease was successful. The ENFET has been used for the determination of urea and pesticides; this depends on the chosen enzyme level in the membrane and can be employed in a flow-injection system. The urea sensitive sensor (high enzyme load) has a wide linear range (1–500 mmol/l) a fast response (t₉₅=20 s) and a lifetime greater than 30 days. The application of this sensor to the determination of urea in the waste water from a fertilizer plant and in blood serum is discussed. The second sensor (low enzyme level) was able to detect pesticides in water based on the inhibition of urease. The detection limit was found to be 0.1 µg/l for Carbofuran (10 minutes incubation time, without preconcentration).     

Comparative study of the influence of cavity preparation with high-speed rotation or Er:YAG laser on infiltration of aesthetic restorations

Laser Physics - The aim of the present study was to compare marginal infiltration in Class V cavities prepared on extracted human premolars with either high-speed rotation or a Er:YAG laser. Class...     

Study of the C(3P) + OH(X2Pi) --> CO(X1Sigma(g)+) + H(2S) reaction: a fully global ab initio potential energy surface of the X2A' state

The C((3)P) + OH(X (2)Pi) --> CO(X (1)Sigma(g)(+)) + H((2)S) reaction has been investigated by ab initio electronic structure calculations of the X(2)A' state based on the multireference (MR) internally contracted single and double configuration interaction (SDCI) method plus Davidson correction (+Q) using Dunning aug-cc-pVQZ basis sets. In particular, the multireference space is taken to be a complete active space (CAS). Improvement over previously proposed potential energy surfaces for HCO/COH is obtained in the sense that present surface describes also the potential part where the CO interatomic distance is large. A large number of geometries (around 2000) have been calculated and analytically fitted using the reproducing kernel Hilbert space (RKHS) method of Ho and Rabitz both for the two-body and three-body terms following the many-body decomposition of the total electronic energies. Results show that the global reaction is highly exothermic ( approximately 6.4 eV) and barrierless (relative to the reactant channel), while five potential barriers are located on this surface. The three minima and five saddle points observed are characterized and found to be in good agreement with previous work. The three minima correspond to the formation of HCO and COH complexes and to the CO + H products, with the COH complex being a metastable minimum relative to the product channel. The five saddle points correspond to potential barriers for both the dissociation/formation of HCO and COH into/from CO + H, to barriers for the isomerization of HCO into COH and to barriers for the inversion of HCO and COH through their respective linear configuration.