Promising optimization of the CeO2/CeCl3 cycle by reductive dissolution of cerium(IV) oxide

Although thermochemical cycles could constitute a promising approach to large-scale hydrogen production, physicochemical studies have shown that they will be difficult to implement because of poor reactivity. Most cycles involve solid–gas systems in which the reactivity is limited by interface passivation processes. To mitigate this difficulty a new approach is described based on a preliminary study performed with the UT-3 cycle. Replacing bromine by chlorine and iron by cerium not only simplifies the cycle from four reactions to three, but also allows the use of much less hazardous reactants while ensuring greater theoretical energy efficiency than the UT-3 cycle. In the proposed new reaction architecture the cycle can be partially carried out in the aqueous phase by reductive dissolution of cerium(IV) oxides to cerium(III) chlorides in an azeotropic hydrochloric acid solution. This has many advantages and could be used to optimize the operating temperatures, enhance reaction progress by eliminating reaction products at the interface, enhance the reaction kinetics by eliminating the solid diffusion layers, systematically regenerate the reactants within the process itself, and also facilitate gas separation by differential solubility. The assessment also shows that photon activation by dissociation of chlorine radicals during the first step, the reverse Deacon reaction, could allow the first two reactions to occur at lower temperatures near 100 °C.     

Synthesis of Spiro[piperidine‐3,3′‐oxindoles] via Gold(I)‐Catalyzed Dearomatization of N‐Propargyl‐ and N‐Homoallenyl‐2‐bromotryptamines

N‐Propargyl‐ and N‐homoallenyl‐2‐bromo‐β‐tryptamines undergo gold(I)‐catalyzed dearomatizing cyclizations to afford 2‐bromospiroindolenines that are in situ hydrolyzed to furnish spirooxindoles in a one‐pot process. Tryptophane derivatives (R²=CO₂Et) led upon cyclization to chiral spirooxindoles in excellent diastereoselectivities.

     

Method for Accurate Surface Temperature Measurements During Fast Induction Heating

A robust method is proposed for the measurement of surface temperature fields during induction heating. It is based on the original coupling of temperature-indicating lacquers and a high-speed camera system. Image analysis tools have been implemented to automatically extract the temporal evolution of isotherms. This method was applied to the fast induction treatment of a 4340 steel spur gear, allowing the full history of surface isotherms to be accurately documented for a sequential heating, i.e., a medium frequency preheating followed by a high frequency final heating. Three isotherms, i.e., 704, 816, and 927°C, were acquired every 0.3 ms with a spatial resolution of 0.04 mm per pixel. The information provided by the method is described and discussed. Finally, the transformation temperature Ac1 is linked to the temperature on specific locations of the gear tooth.     

Heart rate dynamics during sinusoidal exercise: comparison of the control system between children and adults.

The aim was to model the dynamics of heart rate (HR) response to sinusoidal work rate (WR) forcing in children and adults. Seven pre-pubertal boys (aged 10-13) and five adult males (aged 22-37) were studied. Continuous ECG recordings were obtained during the following physiological manoeuvres: five constant amplitude ergometer exercises with WR varying sinusoidally with periods of 0.75, 1, 2, 3.5, and 5 min duration, and one step exercise at a constant WR equal to the midpoint of the sinusoid amplitude. The amplitude ratio (AR; standardized by WR) of the fundamental harmonic of the HR response and the phase shift (phi) between the WR to HR were calculated by Fourier analysis. The HR dynamic parameters (gain and time constant (tau)) of a first order model with or without delay (Td) were also estimated. The AR in children was always higher than that in adults, in absolute terms, but not as a function of body weight. The phi was more delayed in the children than the adults only for the shortest period, i.e. 0.75 min. The tau for the first order model, either without or with Td, was found to be no difference between children and adults (44.7 vs. 45.9 s (without Td), 34.9 vs. 42.3 s (with Td)). Td, however, was longer in the children (6.6 vs. 2.3 s). The goodness of fit for the first order model with Td was better than that without Td in children, i.e. due to the difference of phi for 0.75 min period, whereas the HR dynamics in adults was appropriately described by first order model without Td. It is concluded that the fundamental control of HR to sinusoidal exercise between children and adults was not appreciably different, except for a small Td difference at high sinusoidal frequency.     

Development and operation of alternative oxygen electrode materials for hydrogen production by high temperature steam electrolysis

High temperature steam electrolysis (HTSE) is one of the most promising ways for hydrogen mass production. To make this technology suitable from an economical point of view, each component of the system has to be optimized, from the balance of plant to the single solid oxide electrolysis cell. At this level, the optimization of the oxygen electrode is of particular interest since it contributes to a large extent to the cell polarization resistance. The present paper is focused on alternative oxygen electrode materials with improved performances compared to the usual ones mainly based on perovskite structure. Two nickelates, with compositions La₂NiO_4+δ and Nd₂NiO_4+δ are investigated and evaluated in HTSE operation at the button cell level. The performances of the Ln₂NiO_4+δ - containing cells (Ln = La, Nd) is improved compared to a cell containing the classical Sr-doped LaMnO₃ (LSM) perovskite oxygen electrode showing that nickelates are promising candidates for HTSE oxygen electrodes, especially for operation below 800 °C. Indeed, current densities determined at 1.3 V are 1.1 times larger for the La₂NiO_4+δ - containing cell and 1.6 times larger for the Nd₂NiO_4+δ one compared to the LSM - containing cell at 850 °C, whereas at 750 °C they are 1.8 and 4.4 times larger, respectively. Thanks to the use of a reference electrode, by coupling impedance spectroscopy and polarization measurements, the overpotential of each working electrode is deconvoluted from the complete cell voltage under HTSE operating conditions.     

Spatial point process models for location-allocation problems

The problem of finding an optimal location frequently occurs in geomarketing, economics and other fields: positioning a new branch of a bank, a supermarket, a fire station, a plant, designing a traffic network, etc. The optimal location of the source facility is the argument-minimum of an optimization problem parametrized by some characteristics of the clients. The random nature of some of these characteristics has already been recognized, but few stochastic models for location-allocation problems address the issue of uncertainty of the locations of the clients, and even then they do it with very naive tools. It is proposed to recognize uncertainty in the spatial positions of the clients, and possible spatial autocorrelation as well, by considering the random inputs of the optimization as one realization of a spatial marked point process. The method, called SPP location-allocation, involves fitting a point process model, simulating from the adjusted process, and solving a family of optimization problems for each simulated set of observations. The advantage of this approach over the deterministic one is twofold: it gives an indication of the spatial variability of the optimal solution, and it allows one to solve larger problems. Finally an application to the optimal positioning of a new fire station in the Toulouse area (France) is presented with some heuristic algorithms.     

Nuclear Data Sheets update for A=111: Last evaluation: B. Harmatz, Nuclear Data Sheets 27, 453 (1979)

The 1979 evaluation of A=111 (79Ha20) has been revised. Detailed level and decay schemes are presented for the nuclei of the A=111 mass chain. The level properties obtained from decay and reaction experiments are shown in the drawings. Experimental methods, references, and comments are given in the text.     

Reachability and confluence are undecidable for flat term rewriting systems

Ground reachability, ground joinability and confluence are shown undecidable for flat term rewriting systems, i.e., systems in which all left and right members of rule have depth at most one.     

Inferential processes in clinical work: Inquiry into logical errors that affect diagnostic judgments.

We explore the implications of the experimental findings of attribution theorists for practice, training, and research in the domain of counseling and psychotherapy. Research literature contains abundant evidence that people engage routinely in inferential processes that are logically deficient and lead to erroneous social judgments. Clinical psychologists, no less than others, are engaged in work that is highly inferential in character and that offers continuous opportunity for error in matters that have the most profound consequences in the lives of their clients. Certain sources of error are explored. Emphasis is given to the question of the accuracy and representativeness of the data about clients' lives and the hypotheses derived from those data. The evidence suggests that an objective of every training program in clinical psychology or psychiatry should be the instruction of students in the rigorous application of principles of inferential reasoning within the systems in which they choose to design their treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)