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.     

Couplage okydatif facile d'anions substitues captodativement

Carbanions carrying captodative substitution are readily oxidized to their dimers.     

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).     

Ion spray-tandem mass spectrometry of supramolecular coordination complexes

Double-helical [M₂L₂] ⁿ⁺, triple-helical [M₂L₃] ⁿ⁺, and toroidal [M₃L₃] ⁿ⁺ (M = Cu, Co, Fe, Ni, La, Eu, Gd, Tb, or Lu) supramolecular complexes have been fully characterized by ion spray mass spectrometry (IS-MS). The IS-MS spectra from pure acetonitrile solutions reflect the nature of the cations present in solution with conservation of the charge state and allow an efficient qualitative speciation of the compounds. The mass spectrometry results can be correlated with other powerful techniques (nuclear magnetic resonance and electronic spectroscopy) for the characterization of supramolecular complexes in solution, Structural information is obtained by collision-induced dissociation, which strongly depends on the metal ions used in the supramolecular complexes and on the various connectivities and topologies of the ligands. When the ligand contains 3,5dimethoxybenzyl groups bound to the benzimidazole rings, the partial fragmentation of the complexes is associated with a decrease of the total charge of the complexes and the appearance of the characteristic fragment at m/z 151 that corresponds to the 3,5-dimethoxybenzyl cation. A detailed analysis of the fragmentation pathways of these supramolecular complexes suggests that the metal-nitrogen coordination bonds are very strong in the gas phase.     

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.     

Crystal violet combined with Merocyanine 540 for the ex vivo purging of hematopoietic stem cell grafts

The purpose of this study was to determine in a preclinical purging model, how effective crystal violet-mediated photodynamic therapy (CV-PDT) is against solid tumor and drug-resistant mutant tumor cells, and if certain limitations of CV-PDT can be overcome by using crystal violet (CV) in combination with the membrane-active photosensitizer, Merocyanine 540 (MC540). When used under conditions that preserved an adequate fraction of normal human granulocyte/macrophage progenitors (CFU-GM), CV-PDT failed to achieve meaningful reductions of DU145 prostate, H69 small cell lung cancer, and MDA-MB-435S breast cancer cells. Melphalan-resistant L1210/L-PAM1, adriamycin-resistant P388/ADR, and adriamycin-resistant HL-60/ADR leukemia cells were markedly less sensitive to CV-PDT than their wild-type counterparts, whereas cisplatin-resistant H69/CDDP cells were more sensitive than wild-type H69 cells. Sequential exposure to MC540- and CV-PDT under conditions that preserved an adequate fraction (73% and 29%, respectively) of normal CD34-positive hematopoietic stem cells and granulocyte/macrophage progenitors was highly effective against H69 (99.997% reduction) and H69/CDDP (99.999% reduction) cells, but ineffective against HL-60/ADR, MDA-MB-435S, and DU145 cells. CV thus shows only limited promise as a single-modality purging agent. However, in certain situations, clinically meaningful tumor cell depletions can be obtained by using CV in combination with a second photosensitizer such as MC540.     

Interactions magnétiques dans des groupements binucléaires du Ruthénium +V

The cationic ordering in the $\text{Ba}\text{M}{}_{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{Ru}{}_{\mathrm{<mtext>2</mtext><mtext>3</mtext>}}\text{O}{}_3\text{(M =}\text{Mg, Ca, Cd, Sr}\text{)}$ oxides which crystallize with the 6H structure gives rise to Ru⁵⁺Ru⁵⁺ pairs in (Ru₂O₉) clusters. The magnetic properties have been analyzed on the basis of the Heisenberg-Dirac-Van Vleck model: The d electrons are localized on each Ru⁵⁺ ion and interact strongly through antiferromagnetic exchange. The susceptibility curves agree with the H.D.V.V. model. The values of the exchange integrals have been determined by fitting the experimental values.     

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.     

A study of the electrospray ionisation and ion-trap fragmentation of [M - H](-) ions of new 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazin-2-thiones

The electrospray ionisation (ESI) in negative mode of the pharmacologically significant 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazin-2-thiones, and their subsequent fragmentations using an ion-trap mass spectrometer, have been investigated. Experiments on sequential product ion fragmentations (MS(n)) were performed in order to elucidate the degradation pathways for these compounds. The data presented show that the fragmentation of the even-electron [M - H](-) ions could proceed through an internal nucleophilic substitution displacement. Decarboxylation and extrusion of carbon disulfide are other fragmentations observed.