A Study of premixed propagating flame vortex interaction

Experimental data is presented for the interaction between a propagating flame and a simple vortex flow field structure generated in the wake of solid obstacles. The interaction between gas movement and obstacles creates vortex shedding forming a simple flow field recirculation. The presence of the simple turbulent structure within the gas mixture curls the flame front increasing curvature and enhancing burning rate. A novel twin camera Particle Image Velocimetry, PIV, was employed to characterise the flow field recirculation and the interaction with the flame front. The technique allowed the quantification of the flame/vortex interaction. The twin camera technique provides data to define the spatial variation of both the velocity of the flow field and flame front. Experimentally obtained values of local flame displacement speed and flame stretch rate are presented for simple flame/vortex interactions.     

Derivatization in aqueous solution, isolation and separation of tetrahydro-beta-carbolines and their precursors by liquid chromatography

Derivatization of indole ethylamines and 1,2,3,4-tetrahydro-beta-carbolines in aqueous solution with methyl chloroformate has been used to facilitate the isolation of these compounds. The initial derivatization eliminated the potential for the artifactual formation of these compounds via the condensation of the indole ethylamine with an aldehyde or alpha-keto acid during the work-up procedure. The derivatized compounds possessed improved chromatographic properties which allowed for their facile separation by reversed-phase liquid chromatography and their fluorescent detection at the nanogram level.     

High-performance liquid chromatographic analysis of free long chain fatty acids produced during lipolysis by anaerobic digestor sludge

The development of sample extraction techniques in conjunction with application of a modified version of an established HPLC technique allowed the rapid estimation of concentrations of long chain fatty acids (LCFA) produced by the lipolytic activity of bacteria in anaerobic digestor sludges or experiments using the sludges as inocula. It was established that free long chain fatty acids will preferentially partition into certain phases in the sludge or experimental cultures. These data, and application of the developed techniques for monitoring of LCFA, may lead to the avoidance of toxicity and failure of full-scale anaerobic digestors treating high lipid content waste in the future.     

Mechanistic studies of chelating resins using two-phase potentiometry

The elucidation of metal ion binding mechanisms with chelating resins by treating the resin as a collection of monomeric units is an established approach. In this paper, this approach is used to treat data obtained from two-phase potentiometric titrations by the programme ESTA. Apparent protonation and formation constants could be calculated. From these, species distribution plots could be obtained. These, in turn, allowed the calculation of the more familiar distribution ratios. The method was tested on Fe(III) and Nd(III) bonding with the iminodiacetate functionalized resin, Chelex 100; and Ca(II) bonding to the aminomethylphosphonate functionalized resin, Purolite S940. Good results were obtained indicating the applicability of this method. Comparisons with the literature are made.     

Bisallyl and bismethallyl derivatives of 2,3-dihydroxypyridine

2,3-Dihyroxypyridine has been dialkylated with allyl bromide and methallyl chloride to give 1-allyl-3-allyloxy-2-pyridone ( 2 ) and 1-methallyl-3-methallyloxy-2-pyridone ( 3 ), respectively. These compounds readily undergo a Claisen rearrangement at 163° to give the bis-1,4-allyl-3-hydroxy-2-pyridone isomers, 4 and 5 , respectively. 2,3-Bisallyloxypyridine ( 8 ) and 2,3-bismethallyloxypyridine ( 9 ) were synthesized from 2-chloro-3-hydroxypyridine.     

Cellulose Iβ investigated by IR-spectroscopy at low temperatures

Highly crystalline oriented Halocynthia roretzi cellulose Iβ films were investigated by IR-spectroscopy between ?180 and +10 °C. Changes in the IR-spectra induced by temperature were compared to published changes induced by mechanical stretching. This made it possible to conclude that frequency shifts in the O–H stretching region of the IR-spectra due to temperature were not predominantly an indirect effect of thermal expansion leading to greater O–O distances, but were due directly to the effect of temperature on the O–H···O hydrogen bonds. Temperature induced frequency shifts of C–H stretching bands were consistent with the presence of weak inter-sheet C–H···O bonds. Furthermore, no phase transition in cellulose Iβ was found between ?180 and +10 °C.     

An investigation of calibration materials for the measurement of metals in ambient particulate matter on filters by LA-ICP-MS

Three different types of simple and low-cost calibration material for the measurement of the metals content of ambient particulate matter (PM) on filters using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) have been compared: cellulose ester filters spiked with multi-element calibration solutions, pellets of compressed ambient particulate matter certified reference material (CRM), and powdered ambient particulate matter CRM adhered to a surface. Elements determined were As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn, each at approximate levels of 1000?ng per filter. Blank filters spiked with multi-elemental standards were found to be significantly more reproducible and repeatable than materials based on powdered reference materials. However, a comparison of these spiked filters with real samples of ambient PM showed that the analytical sensitivities obtained per mass of analyte were significantly different. It is concluded that the spiked filters could act as very effective quality control standards correcting, to within 1%, drifts in LA-ICP-MS measurements of up to 10%, or as indirect calibration materials supported by additional measurements using traditional wet chemical techniques.     

Use of labelled nitrogen to measure gross and net rates of mineralization and microbial activity in permanent pastures following fertilizer applications at different time intervals

Measurements of some of the main internal N-cycling processes in soil were obtained by labelling the inorganic N pool with the stable isotope of nitrogen ((15)N). The (15)N mean pool dilution technique, combined with other field measurements, enabled gross and net N-mineralization rates to be resolved in grassland soils, which had previously either received fertilizer N (F), or had remained unfertilized (U) for many years. The two soils were subdivided into plots that received N at different time intervals (over 3 weeks), prior to (15)N measurements being made. By this novel approach, possible 'priming' effects over time were investigated to try to overcome some of the temporal problems of isotopic labelling of soil N (native plus fertilizer) and to identify possible changes in a range of primary N-transformation processes. The results suggested that an overall stimulation of microbially mediated processes occurred with all N treatments, but there were inconsistencies associated with the release of N, both in the timing and the degree to which different processes responded to the application of fertilizer N. The rates of these processes were, however, within the range of previously reported data and the (15)N measurements were not adversely affected by the differences in N pools created by the treatments. Thus, the mean pool dilution technique was shown to be applicable to agricultural soils, under conditions relevant to grass swards receiving fertilizer. For example, between the U and F treatments, the size of inorganic N pools increased by five-fold and gross rates of mineralization reached 3.5 and 4.8 microg N g(-1) (dry soil) d(-1), respectively, but did not vary greatly with the timing of N applications. A correlation (r(2) = 0.57) was found between soil respiration (which is relatively simple to measure) and net mineralization (which is more time consuming), suggesting that the former might be used as an indicator of the latter. Although this relationship was stronger in previously unfertilized soils, the similarities found with fertilized soils suggest that this approach could be used to obtain information of wider agronomic value and would, therefore, warrant further work under a range of soil conditions.