The synthesis of some pyrrolo[1,5-b:2,3-c′]dipyridazines

A facile method for the preparation of the aromatic pyrrolo[1,5-b:2,3-c']dipyridazine ring system is reported. A number of compounds have been prepared and the biological screening data reported.     

Synthesis in the diazasteroid group VI. A synthesis of 2,3-dimethoxy-15-methyl-8,15-diazaestra-1,3,5(10)triene

Homoveratrylamine (II) was condensed with 3-(2-carbomethoxyethyl)-1,3-dimethyl-2-pyrrol-idone (Ib) to furnish the corresponding amide (III), which was subjected to the Bischler-Napieralski reaction to afford the corresponding dihydroisoquinoline derivative (IV). Compound V was obtained by the reductive ring closure of Vila which was obtained by the hydrogena-tion of IV. The stereochemistry of V is proposed to have the anti-trans-trans quinolizidine conformation.     

The correlation of XPS analysis with electrochemical history in aqueous corrosion

The response of the surface composition of aluminium brass to electrochemical polarization is sea water has been studied by XPS in an attempt to elucidate the behaviour of condenser tube surfaces in marine environments. Individual specimens were polarized at 100 mV intervals between +100 and ?1200 mV (SHE) for a charge transfer of 500 mA s. The rather complex spectra were normalised using Jorgenson's factors to permit meaningful discussion of the surface chemistry. In addition an ion etching was used to remove the high surface coverage of carbon molecules picked up from solution. The validity of each of these techniques, necessary for examination of samples removed from the aqueous phase, is discussed. In the present case they permit the observation of a strong correlation between the Mg⁺⁺/Cl^? ratio and the surface potential. The movement of the ratio gives a nice demonstration of cathodic basicity and anodic acidity in accord with electrochemical concepts. This result may be of practical use in ascertaining whether corrosion pits on industrial plant are still active.     

Chemical shifts in Al—Si compounds by Zr Lα photo-electron spectrometry

The excitation of XPS spectra by Zr Lα radiation has the advantage that both the 1s peaks and their KLL Auger series are excited. This paper compares the peak positions, of metals, oxide and certain aluminosilicates, obtained using Zr Lα radiation and thus demonstrates a dependence of the Auger parameter on structures. This method of characterisation is particularly suitable for minerals such as silicates which are prone to charging, but is not possible for silicon with the conventional Mg and Al sources.     

The relationship between transmission efficiencies in the FRR and fat modes of an electron spectrometer

The electron transmission efficiency as a function of kinetic energy for an electron spectrometer operating in the fixed analyser transmission (FAT) mode has been determined by direct comparison with the known transmission efficiency in the fixed retard ratio (FRR) mode. Results obtained from the background intensity and from the relative peak heights of a number of elements compare well with each other. They suggest that transmission in the FAT mode is nearly independent of kinetic energy.     

A full 3D numerical model of the industrial electrostatic coating process for moving targets

In this paper, a full three dimensional FLUENT numerical model of the electrostatic coating process as used in the automotive industry is presented and selected parametric studies on the numerical model have been conducted. The model incorporates a moving mesh capability in order to simulate movements of the target. The target follows piecewise linear motion and the entire area of the target has been coated in multiple passes. All the dominant mechanical and electrical phenomena were taken into account and cases with both neutral and charged particles were examined. It was confirmed that the transfer efficiency increases when the electrical forces are present in the model and that the coating uniformity improves with the movement of the target. The deposition pattern corresponds to the motion of the target and gradually builds up in a cumulative manner. Due to the aggregation effect associated with the target movement, the deposition uniformity is dramatically improved.     

The synthesis of substituted pyrazino[2,3-d]-1,2,4-triazolo[4,3-b]pyridazines

The synthesis of 1,2,4-triazolo[4,3-b]pyridazines and the unknown ring system, pyrazino[2,3-d]-1,2,4-triazolo[4,3-b]pyridazine, has been achieved. The preparation of the new tricyclic 1,2,4-triazole was accomplished first by ring closure of the triazole ring followed by formation of the pyrazine ring. Substitution of the pyrazino[2,3-d]-1,2,4-triazolo[4,3-b]pyridazine ring system was carried out in order to provide information of its reactivity and to provide a variety of interesting compounds for biological testing.     

A method of test for residual isophorone diisocyanate trimer in new polyester-polyurethane coatings on light metal packaging using liquid chromatography with tandem mass spectrometric detection

A method of test for residual isophorone diisocyanate (IPDI) trimer in experimental formulation polyester-polyurethane (PEPU) thermoset coatings on metal food packaging is described. The method involves extraction of coated panels using acetonitrile containing dibutylamine for concurrent derivatisation, and then high performance liquid chromatography with electrospray ionisation tandem mass spectrometric detection (LC-MS/MS). Single laboratory validation was carried out using three different experimental PEPU-based coatings. The calibrations were linear, the analytical recovery was good, no interferences were seen, and substance identification criteria were met. The detection limit of the method is around 0.02 micro g/100 cm(2) of coating, which for a typical sized can and assuming complete migration of any residual IPDI trimer, corresponds to about 0.2 micro g/kg food or beverage. Separate studies indicated that, even if migration occurred at such low levels, the IPDI trimer would not be expected to persist in canned aqueous or fatty foodstuffs as it would hydrolyse to the corresponding aliphatic amine or react with food components to destroy the isocyanate moiety. The method of test developed here for residual IPDI trimer in thermoset polyester-polyurethane coatings should prove to be a valuable tool for investigating the cure kinetics of these novel coatings and help to guide the development of enhanced formulations.