Montedison S.p.a.

Consiglio Nazionale Delle Ricerche

Istituto Guido Donegani S.p.a.

Adriano Mattera

Lucio Zanotti

Giovanni Zuccalli

Roberto Fornari

Renato Magnanini

Catia Bastioli

Paolo Parrini

Giuseppe Gianotti

Marino Quaglino

Massimo Stolfi

Carolo Paorici

Pasqualino Spighi

Carlo Paorici

An interface circuit to the output of a programmable voltage ramp generator for decreasing the minimum voltage step of such a generator having two voltage channels and a minimum voltage step greater than 1 millivolt. The interface circuit receives an input from each of the two voltage channels (V.sub.2, V.sub.3), along with an inserted voltage (V.sub.1). The circuit includes a summing amplifier for (i) compressing the minimum voltage step from one voltage channel (V.sub.2) by a factor equal to or greater than such minimum voltage step, (ii) adding the voltage from the other channel (V.sub.3) to the compressed voltage, and (iii) subtracting the inserted voltage (V.sub.1) (or adding an inserted voltage which is negative). The inserted voltage (V.sub.1) is equal in magnitude to the maximum output value from the voltage channel that has the voltage compressed (V.sub.2). The output of the summing amplifier (V.sub.out) may be represented by:

Programmable - voltage - generator interface for decreasing the minimum

Undoped GaAs single crystals with low dislocation density, low impurity content, 0.20-1 Kg in weight and constant diameter of 1'-2' (inches), said single crystals being obtained with LEC technology at low or high pressure with synthesis of the polycrystal in situ and subsequent growth of the single crystal.

Gallium arsenide single crystals with low dislocation density and high

Process for preparing poly-piperazinamide, anisotropic shaped articles comprising the preparation of the polymer solution in a polar organic solvent, the transformation of the solution into shaped bodies by spreading or spinning, the gelation of the shaped articles by phase inversion, and, optionally, the heat treatment of the gellified shaped articles.

Process for preparing poly-piperazinamide anisotropic shaped articles

Disclosed is a process for removing boron compounds from aqueous effluents. The effluents are contacted, under stirring, with a divalent metal sulphate Me.sub.I SO.sub.4 and a divalent metal hydroxyde Me.sub.II (OH).sub.2, the sulphate-hydroxyde couple being selected from the group consisting of BeSO.sub.4 --Ba(OH).sub.2 ; BeSO.sub.4 --Sr(OH).sub.2 ; BeSO.sub.4 --Ca(OH).sub.2 ; MgSO.sub.4 --Ba(OH).sub.2 ; MgSO.sub.4 --Sr(OH).sub.2 ; MgSO.sub.4 --Ca(OH).sub.2 ; CaSO.sub.4 --Ba(OH).sub.2 ; CaSO.sub.4 --Sr(OH).sub.2 ; SrSO.sub.4 --Ba(OH).sub.2 ; ZnSO.sub.4 --Ba(OH).sub.2 ; ZnSO.sub.4 --Sr(OH).sub.2 ; ZnSO.sub.4 --Ca(OH).sub.2 ; CdSO.sub.4 --Ba(OH).sub.2 ; CdSO.sub.4 --Sr(OH).sub.2 and CdSO.sub.4 --Ca(OH).sub.2. The sulfate Me.sub.I SO.sub.4 and the hydroxide Me.sub.II (OH).sub.2, by reaction with each other, cause the sulphate Me.sub.II SO.sub.4 and the hydroxide Me.sub.I (OH).sub.2 to precipitate. The amount of Me.sub.II (OH).sub.2 is at least stoichiometric in respect of the amount of Me.sub.I SO.sub.4 and the precipitation pH is within the range of 7 to 10 when Me.sub.I SO.sub.4 is ZnSO.sub.4, and 10 to 13 in the other cases. At the end of the precipitation the mixture is subjected to decantation and to filtration or centrifugation, thus separating the boron-containing precipitate from the purified effluents.

Process for removing soluble boron compounds from aqueous effluents

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Novara, Italy

Adriano Mattera