Hollow-cathode sputtering source for the production of gas-phase metal atoms of the refractory elements

A simple, versatile hollow-cathode sputtering system for the production of gas-phase metal atoms has been developed. The source has been used to produce gas-phase metal-containing diatomic and polyatomic molecules. Chemiluminscence and laser-induced fluorescence studied have been used to characterize the source and show that it produces high densities (10¹⁴/cm³) of atoms at a low temperature (340 K).     

Extraction and spectrophotometric determination of trace amounts of tin(II) with diphenylglyoxal bis(2-hydroxybenzoylhydrazone)

Diphenylglyoxal bis(2-hydroxybenzoylhydrazone) has been used as a sensitive reagent for the spectrophotometric determination of tin. This reagent forms an orange-yellow complex with stannous ion at pH 3.5–7.0 (λ_max = 455 nm, ? = 2.25 × 10⁴ liter mol^?1/cm^?1 while no reaction is observed with quadrivalent tin. The colored complex extracted into isobutyl methyl ketone has been used for the spectrophotometric determination of trace amounts of tin(II). The molar absorption in the organic solvent is 3.54 × 10⁴ liter mol^?1 cm^?1 and the compound shows its maximum absorbance at 455 nm. The interferences of foreign ions have been determined.     

The Accuracy of Senum and Yang's Approximations to the Arrhenius Integral

The accuracy of the integral of the Arrhenius equation, as determined from the 1^st to the 4^th degree rational approximation proposed by Senum and Yang, has been calculated. The precision of the 5^th to 8^th rational approximations, here proposed for the first time, has also been analyzed. It has been concluded that the accuracy increases by increasing the order of the rational approximation. It has been shown that these approximations to the Arrhenius equation integral would allow an accuracy better than 10⁻⁸ % in the E/RT range generally observed for solid state reactions. Moreover, it has been demonstrated that errors closed to 10⁻² % can be obtained even for E/RT=1, provided that high enough degrees of rational approximation have been used. Thus, it would be reasonable to assume that high degree rational approximations for the Arrhenius integral could be used for the kinetic analysis of processes, like adsorption or desorption of gases on solid surfaces, which can take place at low temperatures with very low values of E/RT. This revised version was published online in August 2006 with corrections to the Cover Date.     

Derivation of a 3D pharmacophore model for the angiotensin-II site one receptor

Summary A systematic search has been used to derive a hypothesis for the receptor-bound conformation of A-II antagonists at the AT₁ receptor. The validity of the pharmacophore hypothesis has been tested using CoMFA, which included 50 diverse A-II antagonists, spanning four orders of magnitude in activity. The resulting cross-validated R² of 0.64 (conventional R² of 0.76) is indicative of a good predictive model of activity, and has been used to estimate potency for a variety of non-peptidyl antagonists. The structural model for the non-peptide has been compared with respect to the natural substrate, A-II, by generating peptide to non-peptide overlays.     

Titration of Anionic Surfactants Using a New Potentiometric Sensor

Abstract

An anionic surfactant ion selective electrode has been developed by coating the Ru?i?ka Selectrode with plasticised polyvinyl chloride containing hyaminedodecylsulfate active substance. The electrode responds to dodecylsulfate, in the range 10^?2 ? 10^?2 mol dm^?3 and has been used for potentiometric titration of micromolar amounts of dodecylsulfate with an accuracy of 0.3%. The influence of several organic and inorganic anions has been investigated.     

The interconversion mechanism between TcO3+ and TcO2 + core of 99mTc labeled amine-oxime (AO) complexes

Density functional theory, employing B3LYP/DZVP and B3LYP/6-31G*(LANL2DZ for Tc), has been used to investigate the interconversion mechanism between formal TcO³⁺ and TcO₂ ⁺ core of ^99mTc labeled amine-oxime (AO) complex, in which two water molecules have been used to simulate the possible interconversion process. The obtained results indicate that the length of amine-amine hydrocarbon backbone of AO ligand has a significant influence on the stabilities of formal TcO³⁺ and TcO₂ ⁺ complex. The interconversion process between TcO–BnAO and TcO₂–BnAO has been amply discussed, which releases the useful information for the further investigation of the structure and hypoxic mechanism of ^99mTc-HL91.     

Synthesis,Characterisation and Catalytic Studies of Iron(III), Cobalt(II), Nickel(II) and Copper(II) Complexes Containing N,O Donor Ligands and Triphenylphosphine

A series of new Schiff base complexes of Fe^III, Co^II, Ni^II and Cu^II containing Ph₃P has been prepared and characterised. The Schiff bases have been prepared by the condensation of salicylaldehyde and naphthaldehyde with the appropriate aniline. The complexes have been characterised by analytical, spectral (i.r., electronic, magnetic, e.p.r., ¹H-n.m.r.) and electrochemical studies. The new complexes have been used as catalysts for aromatic coupling reactions. Higher catalytic activity has been observed for Ni^II compared to the other complexes.     

Standardization of multi-nuclide mixtures by a new spectrum unfolding method

A new spectrum unfolding method has been applied to double-labeled mixtures with excellent results, while the CIEMAT/NIST method has been used for gels. The convenience of applying both methods has been demonstrated with mixtures containing more than three components.⁹⁰Sr+⁹⁰Y,⁸⁹Sr,²⁰⁴TI,⁴⁵Ca and³⁵S nuclides were combined as three, four and five components, and the different quench values and activity ratios were assayed. The discrepancies between computed and experimental activities were also obtained. Mixtures with some of their components below background have been prepared in order to test low-level activities.     

Easy saponification by metal silanolates: application in SPPS and in (S)-5-hydroxynorvaline preparation

Alkali metal trimethylsilanolates, TMSO⁻, M⁺, has been used for efficient conversion of methyl esters into their corresponding anhydrous acid salts under mild non-aqueous conditions. This strategy has been applied to SPPS for the preparation of neurotoxin cyclic analogues and in (S)-5-hydroxynorvaline synthesis.     

195Pt-Kernresonanz in PtII-und PtIV-Verbindungen

The ¹⁹⁵Pt-nmr spectra of several Pt^IV- and Pt^II-complexes have been measured in aqueous solutions. It has been shown that this method has great potentialities for the evaluation of the bonding character in platinum complexes. The ¹⁹⁵Pt-resonance spectra of solutions containing mixed chloro-bromo-complexes of Pt^IV have been used for the estimation of relative stabilities of these complexes. It is pointed out that this method is generally applicable to determine equilibrium constants of platinum compounds.     

A novel blue fluorescent chemosensor for metal cations and protons,based on 1,8‐naphthalimide and its copolymer with styrene

A new blue emitting 2‐allyl‐6‐(2‐dimethylaminoethyloxy)‐benzo[de]isoquinoline‐1,3‐dione, bearing an allylic group has been designed and synthesized. Bulk radical copolymerization has been carried out in order to prepare a fluorescent copolymer, based on styrene. The main photophysical characteristics of the monomeric and polymeric fluorophores have been investigated both in the absence and presence of metal cations and protons. It has been found that the monomeric naphthalimide can be used as a sensor for protons and Zn²⁺, Ni²⁺, Ce³⁺, Cu²⁺, Co²⁺, Ag⁺ cations. The polymeric fluorophore has been shown to be a selective chemosensor for Cu²⁺ cations. Copyright © 2006 John Wiley & Sons, Ltd.     

Separation of heavy ion induced carrier free europium isotopes from bulk quantity of cesium

Theoretical calculation shows considerable cross section for production of^145,146Eu through¹³³Cs(¹⁶O,xn) nuclear reaction. To reduce the trials with costly particle accelerators beam time experimental simulation for separation of carrier free europium from cesium target matrix has been performed. Trace amounts of^152,154Eu have been separated from macro and trace amounts of cesium. A high separation factor has been achieved when 1% HDEHP and 10⁻³M HCl is used as organic and aqueous phase respectively. Trace europium has been successfully back extracted into HCl, ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) medium.     

The Spectrophotometric Determination of Sc in Eriochrome Canine R(Chrome azurol s)- Phosphatidl Choline System

Abstract

Eriochrome cyanine R(chrome azurol S) is used as a color reagent to determine Sc in the presence of phosphatidyl choline, σ = 3.7 × 10⁴ (4.5 × 10⁴). This method has been connected to extraction separation to determine Sc in the presence of rare earth elements, and good results have been obtained.

Phosphatidyl choline(PC) is a biochemical reagent, which can be used as a surfactant. It has been reported that chrome azurol S(CAS) can be used to determine Be in the presence of PC¹ but it has not been reported that eriochrome cyanine R(ECR) and CAS can be used to determine Sc in the presence of PC. This paper has put forward a method by which Sc can be determined. ECR (CAB) has been used as a color reagent and PC as a surfactant. Conditional experiments have been made and this method has been connected to extraction separation. Tributyl phosphate (TBP) extracts Sc from rare earth elements to make a determination and good results have been obtained.     

The pK * for the dissociation of TRISH+ in NaClO4 media

The stoichiometric dissociation constant, pK^*, of TRISH⁺ has been determined from emf measurements in NaClO₄ solutions to 6.0m at 25°C. The results have been used to derive Pitzer coefficients for the interaction of TRISH⁺ with ClO ₄ ^– . The coefficients have been compared to the values in NaCl solutions. The values of pK^* for TRISH⁺ can be used to calibrate pH electrodes in NaClO₄ solutions using TRIS buffers.     

The kinetics and mechanisms of elementary NF2 reactions with O and N atoms

A combined EPR–LMR spectrometer with a fast-flow system has been used to investigate the kinetics and mechanisms of NF₂ reactions with O and N atoms at 298 K. The overall rate constants of these reactions are: k₀ = (2.8 ± 0.4) × 10^?11 cm³/s and k_N = (5.7 ± 0.8) × 10^?11 cm³/s. The stoichiometry of the reactions with respect to O, N, NF₂, F, and NO has been determined. The statistical theory of bimolecular reactions has been used for interpretation of the results obtained.     

Determination of the balance of the nuclear reactor fuel burn-out process by gamma-spectrometry of fission products III

The possibility for the determination of heavy water reactor fuel burn-up on the basis of gamma-spectrometric measurements of the activity quotients¹⁰⁶Ru/¹³⁷Cs and¹³⁴Cs/¹³⁷Cs has been experimentally investigated. The investigation has been carried out on the non-enriched uranium metal fuel of the Czechoslovak Nuclear Power Plant Al. A spectrometer with germanium detector has been used for spectrum analysis of the irradiated fuel gamm-radiation. Burn-up has been determined (1) by the applied here procedure, and (2) from the results of mass-spectrometric determination of the isotopic composition and content of U, Pu and Nd. Two groups of the values obtained have been compared and the influence of the errors of the measured activity quotients on the established deviations has been evaluated.     

Neutron activation and mass spectrometric measurement of129I

An integrated procedure has been developed for measurement of¹²⁹I by neutron activation analysis and mass spectrometry. An iodine isolation procedure previously used for neutron activation has been modified to provide separated iodine suitable for mass spectrometric measurement as well. Agreement between both methods has been achieved within error limits. The measurement limit by each method is about 10⁷ atoms /2 fg/ of¹²⁹I.Operated for the U.S. Department of Energy by Battelle Memorial Institute under contract DE-AC06-76RL0 1830.     

Determination of iron and titanium in kaolins by the method of non-dispersive X-ray fluorescence

The possibility of application of the radioactive source excited X-ray fluorescence analysis for titanium and iron determination in kaolins to the routine test of the refinement process has been studied. The iron content can be determined with a simple counting system using a single-channel pulse height analyser, argon filled proportional counter and¹⁰⁹Cd source of 3 mCi for the excitation of K Fe rays. The samples were analysed both as pellets and powders. The iron content ranged from 0.2–2.5% and titanium from 0.1–0.64%. For simultaneous determination of titanium and iron a Si(Li) spectrometer has been used. The²³⁸Pu source has been used for K Fe and K Ti excitation. It is the most convenient source for simultaneous determination of titanium and iron.⁵⁵Fe is the most efficient source for the determination of titanium alone. The best values of precision and determination limit have been achieved for iron with²³⁸Pu and for titanium with⁵⁵Fe.     

Design and construction of a facility for neutron activation analysis using the 14 MeV neutron generator at HMS Sultan

The potential for using a small, sealed tube, DT neutron generator for neutron activation analysis has been well documented but not well demonstrated, except for 14 MeV activation analysis. This paper describes the design, construction and characterization of a neutron irradiation facility incorporating a small sealed tube DT neutron generator producing 14 MeV neutrons with fluence rates of 2·10⁸ s⁻¹ in 4π (steady state) and 10¹¹ s⁻¹ in 4π (pulsed). Monte Carlo modeling using MCNP4c and McBend9 has been used to optimize the design of this facility, including the location of a thermal irradiation facility for conventional neutron activation analysis. A significant factor in designing the facility has been the requirement to conform with Ionising Radiation Regulations and the design has been optimized to keep potential radiation doses to less that 1 μSv/h at the external walls of the facility. Activation of gold foils has been used for flux characterization and the experimental results agree well with the modeling.     

Vanadium Speciation by XANES Spectroscopy: A Three‐Dimensional Approach

A library of X‐ray absorption near‐edge structure (XANES) spectroscopic data for V^V, V^IV and V^III complexes with a broad range of biologically relevant ligand has been used to demonstrate that three‐dimensional plots of key XANES parameters (pre‐edge and edge energies; pre‐edge and white line intensities) can be used for the prediction of V oxidation states and coordination numbers in biological or environmental matrices. The reliability of the technique has been demonstrated by re‐analysis of the published XANES data for a V^V‐dependent bromoperoxidase.