Electrodeposition of fluorine-doped lead dioxide

The electrocatalytic properties of PbO₂ may be increased by incorporation of some ions such as F⁻. In this review, the preparation of fluorine-doped PbO₂ in the presence of some additives of fluorine-containing compounds (F⁻, potassium salt of nonafluoro-1-butanesulfonic acid C₄F₉O₃SK and Nafion^®) is reported. The mechanism of electrodeposition is discussed. The amount of additives in the deposit depends on the experimental conditions: potential, current density and charge of additive species in the plating solution. The physicochemical properties of doped oxide are very different from those of undoped oxide, accounting for the different electrocatalytic activity of the materials.     

Structure and rotational isomerism of chloroacetyl chloride molecules

The structure of chloroacetyl chloroide (CH₂ClCOCl) molecule in different conformations arising from rotation of the CH₂Cl group about the C-C bond was determined by the Hartree-Fock RHF/6-31G(d) quantum-chemical calculations. The energy difference between the two stable rotamers was estimated at 5.9 kJ mol^?1, and barriers to intramolecular reorientations of the CH₂Cl group were calculated.     

Simultaneous determination of copper,mercury and antimony in biological samples by neutron activation and substoichiometric extraction

A simple and accurate method has been developed for the determination of copper, mercury and antimony by thermal neutron activation analysis involving substoichiometric extraction technique. The results of analysis indicate that copper, mercury and antimony in biological samples can be determined with an accuracy of 5.3%, 5.5% and 6.2%, respectively. Two samples and a standard can be analysed by the proposed method in about 4 hrs. Part of this work was presented at the International Conference on Modern Trends in Activation Analysis, Saclay, Paris, France, October 2–6, 1972.     

Synthesis, structure, theoretical studies, and Ligand exchange reactions of monomeric, T-shaped arylpalladium(II) halide complexes with an additional, weak agostic interaction

A series of monomeric arylpalladium(II) complexes LPd(Ph)X (L = 1-AdPtBu2, PtBu3, or Ph5FcPtBu2 (Q-phos); X = Br, I, OTf) containing a single phosphine ligand have been prepared. Oxidative addition of aryl bromide or aryl iodide to bis-ligated palladium(0) complexes of bulky, trialkylphosphines or to Pd(dba)2 (dba = dibenzylidene acetone) in the presence of 1 equiv of phosphine produced the corresponding arylpalladium(II) complexes in good yields. In contrast, oxidative addition of phenyl chloride to the bis-ligated palladium(0) complexes did not produce arylpalladium(II) complexes. The oxidative addition of phenyl triflate to PdL2 (L = 1-AdPtBu2, PtBu3, or Q-phos) also did not form arylpalladium(II) complexes. The reaction of silver triflate with (1-AdPtBu2)Pd(Ph)Br furnished the corresponding arylpalladium(II) triflate in good yield. The oxidative addition of phenyl bromide and iodide to Pd(Q-phos)2 was faster than oxidative addition to Pd(1-AdPtBu2)2 or Pd(PtBu3)2. Several of the arylpalladium complexes were characterized by X-ray diffraction. All of the arylpalladium(II) complexes are T-shaped monomers. The phenyl ligand, which has the largest trans influence, is located trans to the open coordination site. The complexes appear to be stabilized by a weak agostic interaction of the metal with a ligand C-H bond positioned at the fourth-coordination site of the palladium center. The strength of the Pd.H bond, as assessed by tools of density functional theory, depended upon the donating properties of the ancillary ligands on palladium.     

Synthesis and acute toxicity of some phosphorylated derivatives of ephedrine alkaloids

The results are given of the synthesis and a comparative study of the toxicities of some phosphorylated derivatives of the alkaloids l-ephedrine and d-pseudoephedrine. It has been shown that the introduction of phosphorus- and sulfur-containing fragments considerably lowers the toxicity of the alkaloids. Institute of Organic Synthesis and Coal Chemistry, National Academy of Sciences of the Republic of Kazakhstan, Karaganda. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 406–408, May–June, 1994.     

The ETACS European project for testing the comparability of sensors and analysers

ETACS is the official acronym for the European project "European Testing and Assessment of Comparability of On-line Sensors/Analysers". This project has three main objectives to achieve the comparability of performance data for sensors and analysers in the environmental field. First, to develop a test protocol for validation and comparison of the performance of on-line sensors/analysers. The test protocol is intended to be generic, that is independent of the specific sensors/analysers and the specific parameters to be monitored. Second, the practical testing of this test protocol to assess its applicability and to develop the techniques used. Finally, to achieve widespread acceptance of the test protocol by producer/suppliers, users and relevant authorities to assist its early adoption as an agreed European standard. Laboratory tests for producing the test protocol have been carried out and completed to check the applicability of such a protocol.     

Synthesis of new cardioselective M2 muscarinic receptor antagonists

A series of 5H-dibenz[b,f]azepine derivatives was prepared and evaluated for binding affinities to muscarinic receptors in vitro. Among them, compound 8 showed a high affinity for human recombinant M2 receptors (Ki=2.6 nm), a low affinity for M4 receptors (39-fold less than for M2 receptors) and a very low affinity for M1 and M3 receptors (119- and 112-fold less than for M2 receptors, respectively). The high M2 selectivity of 8 may be attributed to the olefinic bond of the azepine ring. Functional experiments showed 8 to be a competitive antagonist with high affinity to the cardiac (pA2=7.1) and low affinity to the intestinal muscarinic receptors (IC50=0.54 microM). In vivo experiments confirmed the in vitro M, selectivity of 8. Acetylcholine-induced bradycardia was dose-dependently antagonized in rats after both intravenous and intraduodenal administration of 8. In rats, cholinergic functions mediated by M1 or M3 receptors (salivary secretion, pupil diameter, gastric emptying, intestinal transit time) were not affected by the oral administration of 8 even at doses as high as 30 times the antibradycardic effective dose. Furthermore, 8 had no analgesic activity in mice, indicating poor central nervous system penetration. In dogs, nocturnal bradycardia was dose-dependently inhibited by the oral route with a duration of action of about 24 h. Compound 8 appears to be a promising cardioselective antimuscarinic agent for the treatment of dysfunctions of the cardiac conduction system such as sinus or nodal bradycardia ("sick-sinus syndrome") and atrioventricular block.     

Radon and gamma-radiation measurements in schools on the territory of the abandoned uranium mine “Žirovski vrhl”

On the territory of the abandoned uranium mine irovski vrh, Slovenia, indoor radon and gamma dose rate measurements were carried out in nineteen schools from February 10 to May 10, 1995, using scintillation cells and etched track detectors for radon and thermoluminescence dosimeters for gamma-ray detection. In five schools indoor radon levels exceeded 400 Bq·m^-3, which is the proposed Slovene action level. The maximum average radon value of 1600 Bq·m^-3 and the maximum gamma-dose rate of 172 Sv·month^-1 were found in the same school. According to the ICRP 65 methodology, annual effective doses from radon decay products ranged from 0.05 to 6.10 mSv for pupils and from 0.04 to 4.90 mSv for teachers. Gamma dose rates ranged from 0.05 to 0.19 mSv·y^-1 for pupils and from 0.07 to 0.27 mSv·y^-1 for teachers.     

Synthesis and studies of CuHg(NCX)4 (X = S,Se) and their complexes and application of the softness parameter in the elucidation of their structure

Complexes of CuHg(NCS)₄, CuHg(NCS)₂ (NCSe)₂ and CuHg(NCSe)₄ with tetrahydrofuran, dioxane, pyridine, 2-aminopyridine, nicotinamide, bipyridine and phenanthroline have been prepared and comparative studies made. Bipyridine and phenanthroline form cationic—anionic [CuL₃]²⁺ [Hg(SCN)₄]^2? (L = bipy, phen) complexes with CuHg(NCS)₄ and dinuclear bridged complexes with CuHg(NCSe)₄ and CuHg(NCS)₂ (NCSe)₂. For other ligands the nature of the complexes is binuclear or polynuclear. The comparative stability of the -XCN- bridge (X = S, Se) is CuHg(NCSe)₄ > CuHg(NCS)₂ (NCSe)₂ > CuHg(NCS)₄.     

Mechanism of adsorption,electroreduction and hydrogenation of compounds with ethylenic bonds on platinum and rhodium: Part II. Comparison of the electroreduction and catalytic hydrogenation processes

The catalytic liquid-phase hydrogenation of maleic acid on platinum and rhodium has been investigated. It is shown that the rate-determining step of this process as well as of the electroreduction process of maleic acid is the interaction of the chemisorbed particle of maleic acid with the adsorbed hydrogen which is formed at the preceding rapid stage of either the dissociative adsorption of molecular hydrogen, or the electrochemical stage of hydrogen ion discharge. The rate of the process with the same degree of surface coverage with hydrogen and chemisorbed particles of maleic acid does not depend on whether the process is carried out catalytically or electrochemically, on whether maleic acid and hydrogen were preliminarily adsorbed on the surface of the electrode-catalyst or not. With due regard for the mutual influence of chemisorbed particles participating in the rate-determining stage, the main kinetic equations for the electroreduction and catalytic hydrogenation processes have been derived. The difference in the rates of electroreduction of maleic acid on platinum and rhodium, with the same degree of electrode surface coverage with reactants, is shown to be the result of differences in the adsorption heats (or bonding strength with the surface) of hydrogen and maleic acid on these two metals. Experimental procedures are described in Part I [1].