Semiclassical variational study of size effects in neutral and charged jellium droplets

An analytic expression for the total energy of metallic clusters composed ofN identical atoms of valencev and with net chargeQ is obtained by means of a variational solution of the Thomas-Fermi-Weizsäcker energy density functional within the spherical jellium model. The minimum energy is given as an expansion in decreasing powers of the cluster radiusR=r _s Z ^1/3, withZ=vN andr _s the radius per electron of the bulk metal. The coefficients are obtained as functions ofr _s . Terms of volume (R ³), surface (R ²), curvature (R), constant (R ⁰), (1/R) and (1/R ²) are clearly separated in the formula, as well as the different contributions (kinetic, coulombic and exchange-correlation) to each of them. The asymptotic values (R→∞) for the work functions,W(r _s ), and surface energies σ(r _s ), are compared to analogous semiclassical and Kohn-Sham calculations of jellium-like surfaces and to the experimental values. The size dependent behaviour of chemical potentials, μ(R), electron affinities,AF(R), and ionization potentials,IP(R), are easily obtained for any kind of metallic clusters. In particular we discuss the Coulomb and quantum corrections to the coefficients β, δ in the asymptotic formulae:IP?W+β/R andAF?W+δ/R.     

Nucleophilic addition of difunctional reagents to 2,3-dichlorobenzo[b]thiophene 1,1-dioxide

The nucleophilic reactions of 2,3-dichlorobenzo[b]thiophene 1,1-dioxide with - and -glycols, -diamines, and -amino alcohols proceed with cleavage of hydrogen chloride to give the previously unknown 3-monosubstituted derivatives of 2-chlorobenzo[b]thiophene 1,1-dioxide. The second functional group (the hydroxyl group in amino alcohols) does not enter into the reaction.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1602–1604, December, 1972.     

Photochemical Rearrangement of a Steroidal α,β-Epoxylactone. Photochemical reactions,XI [1]

The UV. irradiation of 17β-acetoxy-4α, 5α-epoxy-2-oxaandrostan-3-one ( 7 ) yields 17β-acetoxy-2-oxa-10(5 → 4)abeo-4ζ (H)-androsta-3,5-dione ( 11 ). A non-photochemical synthesis of 11 , proceeding in lower yield, is also described.     

Mass spectra of some 2-methyl-3-(o- and p;-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles

The mass spectra of twelve 2-methyl-3-(o- and p-R-phenyl)-3,3a,4,5,6,7-hexahydro-2H-indazoles which have potentially useful pharmacological properties are presented.     

The influence of the extrapolation method on enthalpies of solution at infinite dilution

Analyses have been performed on solution enthalpy data for KCl and NaCl in water at 298.15 K in the molality range below 1 mol kg^?1. In order to calculate the enthalpy of solution at infinite dilution. ΔH^∞, the available data have been extrapolated using five different methods. The influence of the extrapolation method on ΔH^∞ has been discussed taking into account the discrepancies between the different data sets.     

Simple titrimetric method for the analytical control of macromolecular polypeptides

A simple potentiometric procedure based on the determination of the primary amino groups in macromolecular polypeptides is presented. The method was found suitable for the detection of decomposition processes involving splitting of the peptide chain (liberation of primary amino groups) and deamination. The method has been applied to analysis of corticotropin fragments (ACTH(1-28) and ACTH(1-32)), Angiotensin II, and the basic trypsin inhibitor Kunitz base (Trasylol).     

Tandem on-line continuous separation and determination of arsenic by inductively coupled plasma atomic emission spectrometry

The principle of tandem on-line continuous separation techniques as an alternative means of introducing samples into plasmas was applied to the development of a sensitive, selective and convenient method for the determination of arsenic by inductively coupled plasma atomic emission spectrometry (ICP-AES). Arsenic is continuously extracted as AsI₃ into xylene from the sample dissolved in 0.1 M potassium iodide solution in 7.2 M hydrochloric acid. The xylene phase (containing the analyte) is continuously mixed on-line with NaBH₄ in dimethylformamide and acetic acid solutions. Arsine is thus continuously generated directly from the organic phase and is separated in a gas—liquid separation device which prevents most of the xylene phase vapour from reaching the ICP. The system was optimized for the continuous extraction of AsI₃, the direct generation of arsine from xylene and the final ICP determination of arsenic. Finally, the tandem on-line continuous separation ICP detection system was applied to the determination of arsenic in real samples (white metal, cast iron, cupro-nickel and orchard leaves standard materials). Very good agreement between the experimental results and the certified values was obtained.     

Representation des courbes de vaporus dans les systemes binaires a tension de vapeur non negligeable

The binary system As₂Se₃-As is first described for a constant value of the specific volumeV/m. The results corroborate the data given by other authors. The system is then described by aT-V-x diagram, by using DTA and electron microprobe analysis. From our experimental results and from the literature crystallographic and vapour pressure data, aT-V-x phase diagram was set up, showing the vaporus curves and the eutectic, peritectic and peritectoid invariant planes.

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Zusammenfassung Das binäre System As₂Se₃-As wird zunächst für einen konstanten Wert des specizifischen VolumensV/m beschrieben. Die Ergebnisse bestätigen die Daten anderer Autoren. Danach wird das System imT-V-x-Diagramm beschrieben, wobei DTA und Elektronenmikroproben-Analyse angewandt werden. Von eigenen Versuchsergebnissen und der Literatur entnommenen kristallographischen und Dampfdruckdaten wurden dasT-V-x-Phasendiagramm aufgestellt, das die Dampfdruckkurven und die eutektischen, peritektischen und peritektoiden invarianten Flächen zeigt.

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As₂Se₃-As V/m. , , , T-V-x. , , T-V-x., , , .

     

New type of blue ternary complex of arsenazo I with plutonium (IV) in the presence of hydrogen peroxide: preliminary investigations

The preparation and spectrophotometric properties of a new type of complex compound of arsenazo I with Pu(IV) in the presence of H₂O₂ are described. The new compound has a blue colour, derived from a wide absorption band with a maximum at 610 nm. and a corresponding molar absorptivity of 4 × 10⁴ l. mole⁻¹.cm⁻¹. From 2 hr after its preparation this curious new compound undergoes for several days a steady decomposition accompanied by decolorization. The formation of similar peroxy Pu(IV) complexes has not so far been shown to take place with arsenazo III or with any other “arsenazo-type” reagent.     

Kinetics and mechanism of substitution reactions of complexes,XX

Thermal decomposition of 21 complexes of the type [Co(DH)₂(amine)₂]NCS has been studied under the conditions of thermogravimetric analysis, by using different heating rates. From the thermogravimetric curves apparent kinetic parameters of the pyrolysis reaction have been derived by means of the modified Doyle method. Apparent reaction order increases and apparent activation energy decreases with increasing heating rate. Thus, the obtained kinetic parameters do not characterize the purely chemical reaction, but the complex heterogeneous process as a whole. The explanation of the observed effect is discussed. Results are compared with those obtained with other analogous complexes.

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Zusammenfassung Die thermische Zersetzung von 21 Komplexen des Typs [Co(DH)₂(Amin)₂]NCS wurde thermogravimetrisch bei verschiedenen Aufheizungsgeschwindigkeiten untersucht. Aus den TG-Kurven wurden die scheinbaren kinetischen Parameter der Reaktion mit Hilfe der Doyleschen Methode ermittelt. Bei zunehmender Aufheizungsgeschwindigkeit wächst die scheinbare Reaktionsordnung während die scheinbare Aktivierungsenergie abnimmt. Die erhaltenen chemischen Parameter kennzeichnen nicht die eigentliche chemische Reaktion, sondern den ganzen komplexen heterogenen Vorgang. Die beobachteten Effekte wurden diskutiert und die Ergebnisse verglichen mit Resultaten von Untersuchungen anderer analoger Komplexe.

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Résumé On a étudié par thermogravimétrie, avec différentes vitesses d'échauffement, la décomposition thermique de 21 complexes du type [Co(DH)₂(amine)₂SCN. On a calculé suivant la méthode deDoyle les paramètres cinétiques apparents déduits des courbes d'ATG. L'ordre apparent de la réaction augmente si la vitesse d'échauffement croît, alors que l'énergie d'activation apparente décroît. Les paramètres cinétiques obtenus ne caractérisent que le processus hétérogène complexe et non la réaction chimique proprement dite. Les effets observés ont été discutés et comparés avec les résultats obtenus avec d'autres complexes analogues.

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21 [(D)₂()₂]NS , . . . , , . . , .