Synthesis, characterization and electrochemical studies of the heterometallic diclusters [{Fe2(μ-CO)(CO)6(μ-PPh2)Au}2(diphosphine)] (diphosphine=dppm, dppip, dppe, dppp)

Treatment of [(ClAu)₂(diphosphine)] {diphosphine=bis(diphenylphosphino)methane (dppm), bis(diphenylphosphino)isopropane (dppip), 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp)} with two equivalents of the anion [Fe₂(μ-CO)(CO)₆(μ-PPh₂)]⁻ in the presence of TlBF₄ gives the new heterometallic diclusters [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₂(diphosphine)] that have been isolated and characterized. Their ³¹P-NMR spectra show different patterns as a function of the diphosphine ligand. The electrochemical behavior of these compounds has been investigated and compared with that of the mono- [Fe₂(μ-CO)(CO)₆(μ-PPh₂)(μ-AuPPh₃)] and tricluster [{Fe₂(μ-CO)(CO)₆(μ-PPh₂)Au}₃(triphos)] derivatives.     

The effect of meteorological parameters on radon concentration in borehole air and water

Seasonal and short term variations of ²²²Rn activity concentration in borehole air and water of the borehole drilled in cracked quartzite were studied and possible response on meteorological parameters was examined. Seasonal change of radon concentration in borehole air due to atmospheric temperature was confirmed. Short term variation of radon concentration in borehole air coincided with the atmospheric pressure changes. The strong impact of rainfall on radon concentration values was observed both in air and water environments. The decrease of radon content in borehole air and water followed radioactive decay law exclusively in spring and summer month. Contrary to borehole water, rainfall increased radon concentration in borehole air during spring and summer months only. In this paper the results from two and half years of investigation are presented.     

Non-destructive bulk analysis of the Buggenum sword by neutron resonance capture analysis and neutron diffraction

Two neutron based techniques, neutron resonance capture analysis (NRCA) and time-of-flight neutron-diffraction (TOF-ND) have been used to determine the elemental composition and structure of a precious and very well preserved all-metal sword from the Bronze Age. This Buggenum sword was on loan from the National Museum of Antiquities (NMA) in Leiden (NL). NRCA and TOF-ND experiments have been carried out at a number of more or less identical positions of the sword. The tin-bronze ratio and the relative amounts of some minor elements (Sb, As, Ag, In) have been determined. The results of neutron diffraction measurements showed considerable tin-segregation, and clear indications of hardening on the edges of the blade. In addition, radiographs using Bremsstrahlung revealed the construction of the hilt–blade connection. The work was carried out at the EC Joint Research Centre IRMM in Geel (B) and at the ISIS facility of the Rutherford Appleton Laboratory (UK).     

Co-digestion of agricultural and industrial wastes

The efficiency of anaerobic digestion process is dependent on the type and composition of the material to be digested. This work examines the co-digestion of corn silage, beet pulp silage, carrot residues, and cheese whey in different configurations together with a glycerin fraction — the waste product of transestrification of oils (biodiesel production) in a 25 L bioreactor operated mesophically in a quasi-continuous mode. Co-digestion of corn silage with carrot residues appeared to be more effective than that with cheese whey resulting in the gas production rate equal to 5.9 L L⁻¹ d⁻¹ and 1.4 L L⁻¹ d⁻¹, respectively. The performed experiments showed that a combination of three substrates: corn silage, cheese whey, and glycerin fraction resulted in the highest methane content equal to 61 % and the biogas production rate of 1.8 L L⁻¹ d⁻¹.     

Study of dehalogenation of halogenoanilines using Raney Al–Ni alloy in aqueous medium at room temperature

Abstract  

Dehalogenation of halogenated anilines by action of powdered aluminium–nickel alloy in aqueous alkaline solution at room temperature has been studied. The reaction course was monitored by means of ¹H nuclear magnetic resonance (NMR) spectroscopy. The rates of dehalogenation of 4-bromo-, 4-chloro-, 4-fluoro- and 3-chloroaniline were compared under conditions of minimum necessary excess of Al–Ni alloy as reducing agent in edetane buffer medium at pH 10.9. The dehalogenation rates of halogenated anilines decreased in the following order: 3-chloroaniline > 4-bromoaniline ≥ 4-chloroaniline > 4-fluoroaniline. On the basis of the results obtained in buffers, the dehalogenation method of aqueous solutions of halogenoanilines was verified using NaOH as the base.     

Comparison of the molecular structures of five benzene derivatives as determined independently by gas-phase electron diffraction in two different laboratories: a perspective

The merits and limitations of gas-phase electron diffraction as a technique for determining accurately the structures of small organic molecules are demonstrated by comparing the molecular structures of five benzene derivatives studied in two different laboratories. The existence of many possible representations of the structure of a molecule (r _a, r _g, r _α, r _α⁰, r _e, …), implying differences in the physical meaning of geometrical parameters, is discussed in some detail as it may cause difficulties in a comparison. Also illustrated are different ways of estimating and expressing uncertainties in the geometrical parameters from a gas-phase electron diffraction study.     

Ionic liquids - deanol derivatives as the Diels-Alder reaction solvents

The Diels-Alder reaction between cyclopentadiene and dienophiles in deanol derivatives containing bis(trifluoromethylsulfonyl)imide anion as media have been studied. The effect of the substituents attached to the cation on the endo:exo selectivity as well as the reaction yield have been evaluated in the absence and presence of Lewis acid catalyst - Y(OTf)₃. Catalytic activity of metal triflates and the recycling of chosen catalytic systems have also been investigated      

Preparation of a new Cd(II)-imprinted polymer and its application to determination of cadmium(II) via flow-injection-flame atomic absorption spectrometry

A new cadmium(II)-imprinted polymer based on cadmium(II) 2,2′-{ethane-1,2-diylbis[nitrilo(E)methylylidene]} diphenolate-4-vinylpyridine complex was obtained via suspension polymerization. The beads were used as a minicolumn packing for flow-injection-flame atomic absorption spectrometry (FI-FAAS) determination of cadmium(II) in water samples. Sorption effectiveness was optimal within pH range of 6.6-7.7. Nitric acid, 0.5% (v/v) was used as eluent. Fast cadmium(II) sorption by the proposed material enabled to apply sample flow rates up to 10 mL min⁻¹ without loss in sorption effectiveness. Enrichment factor (EF), concentration efficiency (CE) and limit of detection (LOD, 3σ) found for 120-s sorption time were 117, 39.1 min⁻¹ and 0.11 μg L⁻¹, respectively. Sorbent stability was proved for at least 100 preconcentration cycles (RSD = 2.9%). When compared to non-imprinted polymer the new Cd(II)-imprinted polymer exhibited improved selectivity towards cadmium(II) against other heavy metal ions, especially Cu(II) and Pb(II), as well as light metal ions. Accuracy of the method was tested for ground water and waste water certified reference materials and fortified water. The method was applied to Cd(II) determination in natural water samples.     

Probing the structure, stability and hydrogen storage properties of calcium dodecahydro-closo-dodecaborate

Calcium borohydride can reversibly store up to 9.6 wt% hydrogen; however, the material displays poor cyclability, generally associated with the formation of stable intermediate species. In an effort to understand the role of such intermediates on the hydrogen storage properties of Ca(BH₄)₂, calcium dodecahydro-closo-dodecaborate was isolated and characterized by diffraction and spectroscopic techniques. The crystal structure of CaB₁₂H₁₂ was determined from powder XRD data and confirmed by DFT and neutron vibrational spectroscopy studies. Attempts to dehydrogenate/hydrogenate mixtures of CaB₁₂H₁₂ and CaH₂ were made under conditions known to favor partial reversibility in calcium borohydride. However, up to 670 K no notable formation of Ca(BH₄)₂ (during hydrogenation) or CaB₆ (during dehydrogenation) occurred. It was demonstrated that the stability of CaB₁₂H₁₂ can be significantly altered using CaH₂ as a destabilizing agent to favor the hydrogen release.     

Quality assurance in research: incorporating ISO9001:2000 into a GMP quality management system in a pharmaceutical R+D+I center

There is currently no universal or standardized quality system for the recognition of excellence of a research center. Knowledge and competence may not be enough in the current rapidly changing world in which high productivity and continuous improvement are essential. The purpose of this study was to assess the impacts of implementing the ISO9001:2000:2000 standard in an academic research center dedicated to R+D+I (research, development and innovation) in the pharmaceutical industry. The article describes the stages we followed to implement the ISO9001:2000 system, which was achieved by integrating it into the previous regulatory system of GMP (Good Manufacturing Practices). As a result of implementing ISO9001:2000, the center has seen distinct improvements, such as fewer errors in project documentation, improved assessment of customer satisfaction, and the effective implementation of periodic plans, e.g., in calibration, preventive maintenance, and investments. Overall, ISO9001:2000 implementation has been beneficial for the organization and could be applied to other research centers.