Gamma background measurements in the Laboratoire Souterrain de Modane

In situ gamma-ray measurements were taken at six locations in the Modane Underground Laboratory. Count rates for gamma radiation within the energy range of 7–2734 keV varied from 15 to 108 γs⁻¹. The arithmetic mean was 79 γs⁻¹ for measurements taken without a collimator. The metamorphic rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium equal to 12 and 10 Bq kg⁻¹, respectively.     

Extraction and separation of Th(IV) and U(VI) from nitric acid media using PIA-8 and HDEHP

Extraction behavior of Th(IV) and U(VI) has been investigated with bis(2-ethylhexyl) phosphinic acid (PIA-8) and bis(2-ethylhexyl) phosphoric acid (HDEHP) from nitric acid media in toluene. The optimum conditions for extraction of these metals have been established by studying various parameters like acid concentration, pH, reagent concentration, diluents and shaking time. The extraction of Th(IV) was found to be quantitative with 0.3-2.5M HNO₃ by 2.5^.10^-2M HDEHP and in the pH range 0.1-2.5 with 2.3^.10^-2M PIA-8 in toluene. U(VI) was completely extracted in the acidic range of 0.1-2.0M HNO₃ with 2.2^.10^-2M HDEHP and in the pH range of 1.0-3.0 with 2.0^.10^-2M PIA-8 in toluene. The probable extracted species have been ascertained by log D-log c plot as UO₂ R₂ ^.2HR with both the reagents and Th (NO₃)₂R₂ ^.2HR with PIA-8 and Th (NO₃)₃R^.3HR with HDEHP, respectively. Temperature dependence of the extraction equilibrium is examined by the temperature variation method. Separation of U(VI) and Th(IV) was also carried out from commonly associated metals.     

Computer assisted multielement analysis of terrestrial and extraterrestrial materials and studies on long-lived cosmogenic53Mn by neutron activation

In a large number of alpine rocks and respective mineral separates the beryllium distribution was studied via “non-destructive” photon activation. The detection limit of the assembly was ∼20 ppb. The existence of Be-rich areas was revealed. A selection of individual rocks was analysed by instrumental as well as by radiochemical neutron activation analysis for main and trace elements as: Na, K, Sc, Cr, Mn, Fe, Co, Rb, Cs, La, Eu, Yb, Ta, W, Au, and U. The latter was determined by counting the²³⁵U-fission tracks. The data supply an insight into the complex processes leading to the formation of metamorphic rocks. The hardware and the computer evaluation of the γ-spectra is described in some detail. A further application is the determination of traces of⁵³Mn (in the order of 10⁻¹² g/g) produced by the interaction of cosmic rays with stony meteorites. From a comparison of the²⁶Al- and⁵³Mn-values it is concluded that the depth dependent production of these two radionuclides differs slightly.     

Formation of novel polycyclic cage compounds through ‘uncaging’ of readily accessible higher cage compounds

The synthesis of the novel cage compounds 7-halomethyl-8-(carbomethoxy)tetracyclo[4.2.1.1^4,7.0^2,5]deca-3-(11)-ene-10-ones, methyl-4-methylene-6-oxopentacyclo[5.4.0.0.^2,5.0^3,10.0^7,9]undecane-9-carboxylate, 3-chloromethyl-4-(carbomethoxy)tetracyclo[4.2.1.1.^3,8.0^2,5]deca-7(11)ene-10-one, 2-bromo-5-methyl-8-methylene-6-oxotricyclo[5.3.0.0^3,9]decane-4-carboxylic acid and 2-bromo-5-methyl-8-methylene-6-oxotricyclo[5.3.0.0^3,9]decane-4-methyl carboxylate, achieved through base catalyzed rearrangement, is described.     

Photocatalytic destruction of catechol on illuminated titania

First-order kinetics was found for the photocatalytic oxidation of catechol on TiO₂. Kinetic constants calculated from the Langmuir-Hinshelwood equation are: k=2.03x10^-8 mol dm^-3 s^-1; K_ads=1.63x10⁴ dm³ mol^-1. Full catechol mineralization is a multistep reaction, 1,2,4-benzenetriol and glycol are the main intermediates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Uptake of Tm(III) ions onto polyurethane foam from H2O - ethanol mixture containing 1-(2-pyridylazo)-2-naphthol (PAN)

Summary The sorption of microquantities of Tm(III) ions on washed polyurethane foam (PUF) from a mixture of aqueous solution and ethanol containing PAN was examined. The maximum sorption of 3.18^. 10^-6M solution of Tm(III) ions was observed at pH 8 with 30-minute equilibration time. The optimum ratio of aqueous-ethanol phase for the sorption of Tm(III) ions was found to be 3:1 v/v, respectively. The sorption rate of metal ions on PUF is followed a first order kinetics and obeyed the equation for an intra particle diffusion process. The equilibrium concentration data of Tm(III) ions could be described satisfactorily by several adsorption isotherms. The Freundlich adsorption isotherm constants 1/nand K_Fare 0.66±0.02 and (5.7±0.3)^. 10^-3mol^. g^-1, respectively. The Langmuir isotherm constants for monolayer coverage (Q) and binding strength of sorption (b) are (2.5±0.7)^. 10^-5mol^. g^-1and (1.6±0.1)^. 10⁴l^. mol^-1, respectively. The sorption capacity derived from Dubinin-Radushkevich (D-R) isotherm is (1.7±0.2)^. 10^-4mol^. g^-1and the sorption free energy (E) is 9.8±0.2 kJ^. mol^-1indicating chemisorption phenomena. The thermodynamic parameters indicate that the sorption of Tm(III) ions onto PUF is endothermic, entropy driven and spontaneous in nature.     

Leaching behavior of some radionuclides from cement matrix incorporating exhausted polymeric resins

Exhausted poly(acrylamide-acrylic acid) impregnated with zirconium phosphate {P(AM-AA)-ZrP} produced from the treatment process of radioactive liquid waste was incorporated in different types of cement to prevent widespreading of radionuclides into the human environment. The rates at which ⁶⁰Co, ⁶⁵Zn and ^152,154Eu are leached from Ordinary Portland Cement (OPC) and Blast Furnace Slag Cement (BFSC) were measured. From the leaching data the leach coefficients of ⁶⁰Co, ⁶⁵Zn and ^152,154Eu were determined and were found to vary between 1.62^.10^-8 to 7.06^.10^-10 cm²/day and 1.01^.10^-8 to 8.93^.10^-9 cm²/day in OPC and BFSC, respectively. In general, the radionuclide leaching rates followed the order: ^152,154Eu>⁶⁵Zn>⁶⁰C o. The leach coefficient was found to be dependent on the composition of the leachants and varied in the order: distilled water > ground water > synthetic sea water. The effect of NaNO₃ concentration in the wastes on the leach coefficient of ⁶⁰Co from OPC was also studied     

Synthesis of exo-3-amino-10-hydroxy-hexacyclo[10.2.1.0.0.0.0]pentadecane-5,7-diene-endo-3-carboxyclic acid and endo-3-amino-10-hydroxy-hexacyclo[10.2.1.0.0.0.0]pentadecane-5,7-diene-exo-3-carboxylic acid

Treatment of hexacyclo[7.4.2.0^1,9.0^3,7.0^4,14.0^6,15]pentadecane-10,12-diene-2,8-dione with aqueous sodium cyanide produced 2,8-dihydroxy-hexacyclo[7.4.2.0^1,9.0^3,7.0^4,14.0^6,15]pentadecane-10,12-diene-2,8-lactam and with sodium cyanide, ammonium chloride and ammonium hydroxide, 2-amino-8-hydroxy-hexacyclo [7.4.2.0^1,9.0^3,7.0^4,14.0^6,15]pentadecane-10,12-diene-2,8-lactam was obtained. 10-Hydroxy-hexacyclo [10.2.1.0^2,11.0^4,10.0^4,14.0^9,13]pentadecane-5,7-diene-3-one was converted into the corresponding aminonitrile and hexacyclo[10.2.1.0^2,11.0^4,10.0^4,14.0^9,13]pentadecane-5,7-diene-10-hydroxy-3-spiro-5′-hydantoin. Treatment of the latter with barium hydroxide produced exo-3-amino-10-hydroxy-hexacyclo [10.2.1.0^2,11.0^4,10.0^4,14.0^9,13]pentadecane-5,7-diene-endo-3-carboxylic acid. The isomeric endo-3-amino-10-hydroxy-hexacyclo[10.2.1.0^2,11.0^4,10.0^4,14.0^9,13]pentadecane-5,7-diene-exo-3-carboxylic acid was obtained from 3-cyano-3-ureido-hexacyclo[10.2.1.0^2,11.0^4,10.0^4,14.0^9,13]pentadecane-5,7-diene-10-ol.     

Determination of palladium in synthetic nuclear wastes by differential pulse voltammetry

A novel method for the determination of palladium in synthetic nuclear waste samples has been developed using a computerized voltammetric analyzer. The electrode system consists of hanging mercury drop electrode (HMDE)/glassy carbon/Ag-AgCl electrode. Various experimental conditions including electrolyte type, pH and concentration have been optimized, leading to a detection limit of 40 ng/ml. The mixture of 4^.10^-3M citric acid + 2^.10^-2M ammonia-ammonium chloride buffer + 4^.10^-3M EDTA was used as a supporting electrolyte at pH 9.0. Standard addition method was employed to determine the concentration of palladium present in the nuclear waste sample. The relative standard deviation of the proposed method was found to be 8% at 40 ng/ml of palladium content. The method is direct, simple, rapid and free from any possible interference.     

3,4-Dihydroxybenzoic Acid As A Reagent for the Spectrophotometric Determination of Titanium

Abstract

The reaction between titanium(IV) and 3,4-dihydroxybenzoic acid in aqueous media results in an intensely colored complex which is stable for at least 8h. It allows the spectrophotometric determination of titanium in silicate rocks. The proposed method, in pH 4.0–6.0, shows a molar absorptivity of 1.43.10⁴ L.mole^?1.cm^?1 at 380 nm. Beer's Law is obeyed up to 3.0 μg/mL of titanium(IV). The interference of iron(III) can be eliminated by reduction to iron(II) with hydroxylamine hydrochloride. The method was applied to the determination of titanium in various standard rocks and the results indicated that the accuracy and precision are satisfatory.     

Polarographic and Voltammetric Study of the Sc(III)-Acid Chrome Blue K Complex and Determination of Trace Scandium

Abstract

A new system of polarographic adsorptive wave for determining trace scandium was proposed. In 0.2 mol/L NH₄OAc, the Sc(III)- ACBK [1,8- dihydroxy- 2- (2- hydroxy- 5- sulfo- 1- phenylazo)- 3,6- disulfo- naphthalene, called acid chrome blue K] complex emerged a sensitive adsorptive complex wave(Ep′ = -0.67V). The molar ratio of Sc(III) to ACBK in the complex was established as 1: 2 and the apparent stability constant β₂ = 2.7 × 10¹⁵. But for Y(III), the molar ratio was 1: 1 and β = 1.5 × 10⁵. Because of the particularity of Sc complex, the sensitivity and the selectivity of determination Sc are much better than that of other rare earth ions. The detection limit is 1.1 × 10^?7 mol/L for oscillopolarography and 2.0 × 10^?8 mol/L for adsorptive stripping voltammetry.     

Calcium ion selective membrane electrode

The calcium salts of the mono- and diesters of [4-(1,1,3,3-tetramethylbutyl)phenyl phosphoric acid] have been prepared, and the individual esters as well as mixtures of the esters have been used with several varieties of polyvinyl chloride to construct macro membrane electrodes selective to calcium ions. These electrodes have been calibrated by using solutions of CaCl₂ and Ca ion buffers. The mixed ester electrodes showed Nernstian response in the concentration range 10^-1 to 10^-7M; the diester electrodes showed Nernstian response down to 7.9 x 10^-8M. The detection limit of the mixed ester electrode was 10^-8M, whereas that of the diester electrode was 7.9 x 10^-9M. Contrary to these results, the monoester electrodes showed unsatisfactory behavior. The responses of both the mixed ester and diester electrodes to calcium ions were not affected by the presence of sodium, potassium, or other divalent ions. Only ferric and lanthanum ions showed interferences with the electrode response to calcium ions. p]The electrode response was independent of pH in the approximate range 5–8 at a CaCl₂ concentration of 10^-4M. As the Ca ion concentration was increased, the range of pH independence widened to approximately 4–8. The dynamic response time constant of the mixed ester electrode was in the range 0.7–1.5 sec, whereas that of the diester electrode was in the range 0.5–0.75 sec.     

Cyclization and rearrangements of diterpenoids. IX. Isomerization of (1R,2S,7S,10S,11R,12S,13S)-2,6,6,10,12-pentamethylpentacyclo[10.2.1.01,10.02,7.011,13]pentadecane by fluorosulfonic acid

It has been shown that the opening of the cyclopropane ring in (1R, 2S, 7S, 10S, 11R, 12S, 13S)-2,6,6,10,12-pentamethylpentacyclo[10.2.1.0^1,10.0^2,7.0^11,13]pentadecane takes place under the action of fluorosulfonic acid at all three carbon-carbon bonds, but at low temperatures the main isomerization product is (1R, 2S, 7S, 10S, 12S, 13S)-2,6,6,10,12-pentamethyltetracyclo[10.2.1.0^1,10.0^2,7]pentadecan-13-ol, and at the ordinary temperature the main products are (1R, 2S, 7S, 11S, 12R, 13R)-2,6,6,11,13-pentamethyltetracyclo[10.2.1.0^1,10.0^2,7]pentadeca-9-ene and (1S, 2R, 11S, 12R, 15R)-2,7,7,11,15-pentamethyltetracyclo[10.2.1.0^2,11.0^3,8]pentadeca-3(8)-ene.     

Inorganic ion exchangers in radioactive waste management

The removal behavior of stannic and zirconium phosphates was assessed for Sr(II) ions as a function of sorptive concentration, temperature and pH. It was observed that an increase of these parameters enhanced the removal of Sr(II) ions from aqueous solutions. First order uptake of Sr(II) followed the Freundlich adsorption isotherm for the entire range of sorptive concentration (10^-2 to 10^-8 mol^.dm^-3). The study of temperature dependence showed that the endothermic and irreversible type of uptake proceeds by an ion-exchange type mechanism.     

The determination of boron in rocks by deuteron activation analysis

The determination of boron in rocks by charged particle activation using the¹⁰B(d, n)¹¹C reaction is studied. A sample holder that allows reproducible irradiation of powdered samples is developed.¹¹C is separated as¹¹CO₂. For boron concentrations between 2.35 and 25.2 μg·g⁻¹, the standard deviations ranges from 7.1 to 22.8%. The results for USGS reference silicate rocks and Moroccan phosphate rock are compared to those obtained by other techniques.     

Five-membered 2,3-dioxo heterocycles: XCVIII. [4 + 2]-cycloaddition of alkyl vinyl ethers to 3-aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones. A new synthetic approach to heteroanalogs of 13(14→8)-abeo steroids

3-Aroyl-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones reacted with alkyl vinyl ethers according to the [4 + 2]-cycloaddition pattern with formation of substituted (1S*,16R*)- and (1R*,16R*)-16-alkoxy-14-aryl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-triones. The structure of (1S*,16R*)-7-chloro-16-ethoxy-14-phenyl-3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadeca-4,6,8,13-tetraene-2,11,12-trione was determined by X-ray analysis. A new synthetic approach was developed to heteroanalogs of 13(14→8)-abeo steroids, substituted 3,15-dioxa-10-azatetracyclo[8.7.0.0^1,13.0^4,9]heptadecanes.     

Radiotracer study of sorption of europium on Gorleben sand from aqueous solutions containing humic substances

The sorption of trace europium, as a trivalent actinide homologue, was studied in the system Gorleben sand - aqueous solution with the aim to elucidate its mechanism. Radiotracer method (^152/154Eu) and batch experiments were used. Simultaneously, the distribution of humic substances present in, or added to the system was measured. The evaluation of the sorption was complicated by the adsorption of Eu on the walls of polyethylene vials used for the experiments, which was rather high and had to be taken into consideration. It has been found that Eu sorption on Gorleben sand increases from pH 2 to pH 5-7 and then it decreases. The decrease is due to the complexation of Eu with humic substances leached from Gorleben sand at pH >7. The position of the sorption maximum depends on the composition of the solution and on the liquid-to-solid ratio. It is shifted to lower pH values in the presence of added humic acid (HA), which enhances Eu sorption at low pH values and suppresses it at pH values higher than 5. The regions of the enhancing/suppressing effects coincide with the high/low adsorption of HA on Gorleben sand, respectively. The increasing ionic strength (from 0.01 to 0.1) and europium concentration (3.4^.10^-8 to 9.3^.10^-7 mol/l) suppress the relative sorption (expressed in %) at low pH values and enhance it at pH>6-8. Addition of carbonates (5^.10^-3 mol/l) supports Eu sorption at pH>7.5 so that no decrease with pH is observed till pH 9. Alkaline leaching of the sand significantly changes most of the effects found. These results were qualitatively interpreted and conclusions were drawn on the mechanism of the sorption.     

Silver-Selective Electrode Based on a Direct Modified Electrode Silver Hexacyanoferrate(II) Film

ABSTRACT

A silver hexacyanoferrate(II) modified electrode is introduced as a silver-selective electrode. The electrode was prepared based on a new type of chemically modified electrodes by direct modification of the electrode surface. The electrode response characteristics were investigated by potentiometry. The calibration curve of the electrode shows a linear potentiometric response to Ag⁺ in the range of 10^-7 - 10^-2 M with detection limit of 5 × 10^-8. The modified electrode described in this paper is very simple, low cost and has linear response to Ag⁺ with a slope of 52-55 mV per decade.     

Trace Analysis of Vanadium in Environment as its Ternary Complex with N-p Methoxyphenyl-2-Furylacrylohydroxamic Acid and 3-(o-Carboxyphenyl)-1-Phenyltriazine-N-Oxide

Abstract

A method is presented for the highly sensitive, selective, and rapid determination of vanadium (V) at sub-microgram levels in rocks, animal tissues, plant tissues and natural waters. The method is based on the selective extraction of vanadium (V) from strongly acidic (3-8 M hydrochloric acid) medium with solution of N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in chloroform. The reddish-violet extract (molar absorbance 8.6x10³ 1 mole^?1 cm^?1 at λ max 545 nm) is then equilibrated with 3-(o-carboxyphenyl)-1-phenyltriazine-N-oxide (CPPTNO) at pH = 1.5. The resulting ternary complex has enhanced colour (molar absorbance 1.4 × 10⁴ 1 mole^?1 cm^?1 at Λ max 450 nm). The ternary system obeys Beer's Law at 450 nm over the range 0-18 μ g/ml of vanadium. The extraction system achieves 20-fold enrichment of vanadium and enables the determination of the metal down to parts per billion (ng 1^?1) levels. The method tolerates the presence of a large number of anions and cations which are normally present with vanadium in rocks, plant tissues, animal tissues and natural waters. The applicability of the method was tested by the analysis of vanadium in these matrices. MFHA was selected from nine hydroxamic acids as it provided maximum sensitivity and selectivity.     

Study of Fluorescence System of Gmanylic Acid-Tb3+ and the Determination of Gmanylic Acid

Abstract

It was found that gmanylic acid (GMP) can be selectively completed with Tb³⁺ at pH 6.0-6.6, which then emits strong fluorescence characteristic of Tb³⁺. This reaction can be used for the determination of GMP in presence of adenylic acid (AMP), uridylic acid (UMP) and cylidylic acid (CMP). A linear relationship is obtained between the fluorescence intensity and GMP concentration in the range of 2.0×10^?7 - 1.0×10^?4M. The detection limit is 2.0×10^?8 M. The results showed that the composition ratio and apparent stability constant of GMP-Tb complex were 1:1 for GMP Tb³⁺- and 2.3×10^?5, respectively.