1-Chloroisatin and 2,2-Diphenyl-2,3-dihydro-3-one-1,5,7-trichloroindole: New Oxidants

In 1969 1-chlorobenzotriazole was proposed as a new oxidant, espe cially in view of its ease of preparation, it stability, its mild and rapid action, and the ease of remuval of side products.“¹ In this communication we describe 1-chloroisatin (1) and 2,2-diphenyl -2,3-dihydro-3-one-1,5,7-trichloroindole (2) as new convinient oxi dants.     

Alcoholic Fermentation with Flocculant Saccharomyces cerevisiae in Fed-Batch Process

Studies have been conducted on selecting yeast strains for use in fermentation for ethanol production to improve the performance of industrial plants and decrease production costs. In this paper, we study alcoholic fermentation in a fed-batch process using a Saccharomyces cerevisiae yeast strain with flocculant characteristics. Central composite design (CCD) was used to determine the optimal combination of the variables involved, with the sucrose concentration of 170 g/L, a cellular concentration in the inoculum of 40 % (v/v), and a filling time of 6 h, which resulted in a 92.20 % yield relative to the theoretical maximum yield, a productivity of 6.01 g/L h and a residual sucrose concentration of 44.33 g/L. With some changes in the process such as recirculation of medium during the fermentation process and increase in cellular concentration in the inoculum after use of the CCD was possible to reduce the residual sucrose concentration to 2.8 g/L in 9 h of fermentation and increase yield and productivity for 92.75 % and 9.26 g/L h, respectively. A model was developed to describe the inhibition of alcoholic fermentation kinetics by the substrate and the product. The maximum specific growth rate was 0.103 h^?1, with K _I and K _s values of 109.86 and 30.24 g/L, respectively. The experimental results from the fed-batch reactor show a good fit with the proposed model, resulting in a maximum growth rate of 0.080 h^?1.     

Si-based materials and devices for light emission in silicon

We report on the fabrication and performances of extremely efficient Si-based light sources. The devices consist of MOS structures with erbium (Er) implanted in the thin gate oxide. The devices exhibit strong 1.54 μm electroluminescence (EL) at 300 K with a 10% external quantum efficiency, comparable to that of standard light-emitting diodes using III–V semiconductors. Er excitation is caused by hot electrons impact and oxide wearout limits the reliability of the devices. Much more stable light-emitting MOS devices have been fabricated using Er-doped silicon rich oxide (SRO) films as gate dielectric. These devices show a high stability, with an external quantum efficiency reduced to 1%. In these devices, Er pumping occurs by energy transfer from the Si nanostructures to the rare-earth ions. Finally, we have also fabricated MOS structures with Tb- and Yb-doped SiO₂ which show room temperature EL at 540 nm (Tb) and 980 nm (Yb) with an external quantum efficiency of a 10% and 0.1%, respectively.     

Topological affine spaces

Some characterizations of the topological affine spaces are already known [2,5,6]; they are given via the topologies on the sets of points and hyperplanes. According to the definition made by Sörensen in [6], a topological affine space is an affine space whose sets of points and hyperplanes are endowed with non-trivial topologies such that the joining of n independent points, the intersection of n independent hyperplanes and the construction of parallel hyperplanes are continuous operations. In this paper we give a new characterization of such spaces by means of the topologies on the sets of points and lines.The author wishes to thank the University of Hannover, West Germany, for its hospitality during the time of this research. This work was supported by CNR (National Research Council of Italy).     

On Automorphisms of Flag Spaces

We show that the automorphisms of the flag space associated with a 3-dimensional projective space can be characterized as bijections preserving a certain binary relation on the set of flags in both directions. From this we derive that there are no other automorphisms of the flag space than those coming from collineations and dualities of the underlying projective space. Further, for a commutative ground field, we discuss the corresponding flag variety and characterize its group of automorphic collineations.     

Photoelectron spectroscopy of actinide organometallic compounds I. Bis(cyclooctatetraene)actinide(IV) complexes

The He(I) photoelectron spectra of the antinocene species Th(cot)₂ and U(cot)₂ (cot = cyclooctatetraene) have been determined. The 5f metal ionization has been detected at the onset of the uranocene spectrum. The low ionization energy region of both spectra is discussed in terms of simple qualitative molecular orbital scheme.     

Partial Molar Volumes of Cobalt(III) Complexes. Part 3: Homologous Series of Aminopentaamminecobalt(III) Complexes

Partial molar volumes (V ₂°) have been determined at infinite dilution in aqueous solution at 20 °C for a series of octahedral N₆-coordinated cobalt(III) species having five-coordinated ammonia ligands along with an N-coordinated linear alkyl amine whose alkyl chain was varied from ethylamine to octylamine. The experimental values for V ₂° are consistent with the relative sizes of the ligands but show increasing deviations from those predicted by computer modeling, as the size of the cation increases, presumably due to the void space of the cation that increases with the size of the amine ligand. The value of the partial molar volume at infinite dilution increased by about 16 mL⋅mol⁻¹ with each added methylene group.     

Asymptotic expansion for harmonic functions in the half‐space with a pressurized cavity

In this paper, we address a simplified version of a problem arising from volcanology. Specifically, as a reduced form of the boundary value problem for the Lamé system, we consider a Neumann problem for harmonic functions in the half‐space with a cavity C. Zero normal derivative is assumed at the boundary of the half‐space; differently, at ?C, the normal derivative of the function is required to be given by an external datum g, corresponding to a pressure term exerted on the medium at ?C. Under the assumption that the (pressurized) cavity is small with respect to the distance from the boundary of the half‐space, we establish an asymptotic formula for the solution of the problem. Main ingredients are integral equation formulations of the harmonic solution of the Neumann problem and a spectral analysis of the integral operators involved in the problem. In the special case of a datum g, which describes a constant pressure at ?C, we recover a simplified representation based on a polarization tensor. Copyright © 2016 John Wiley & Sons, Ltd.