ALcontrol Laboratories

Abstract A novel, optimized, polysaccharide and biochar-based, compostable hydrogel horticultural growing substrate for use in hydroponics and vertical farming was created based upon empirical methods and statistical design of experiments (DOE). A 15-run D-optimal mixture DOE was completed that increased the 2-week plant growing ability of a five-component hydrogel nearly ten-fold from 4.3695 g to 41.2623 g per 100 plants. The data were analyzed using a standard least squares method with an effect screening emphasis, and a model was created that maximized the signal to noise ratio. There was a good correlation between the measured and predicted values of the model, with an r-squared value of 0.90. The predictions of efficacy and compostability were confirmed with subsequent experiments that showed the hydrogel was composted in less than 12 weeks and that the plant growth predicted by the model differed from the experimental growth by 0.65%. The resulting optimized formulation had a high fertilizer content for a growth medium. We therefore suggest that an empirical approach to formulation research can produce superior outcomes with a statistically designed study.

The microbial assay for risk assessment (MARA) is an innovative system based on an array of 11 different microbial species freeze-dried in a 96-well micro-titer plate. Developed for testing the toxicity of chemicals, mixtures, and environmental samples, the assay employs species of a taxonomically diverse range. In addition to 10 prokaryotic species, a eukaryote (yeast) is included in the range. The MARA's innate scope of a multi-dimensional test allows determination of toxicity based on a unique assay fingerprint or index, numerically expressed as the mean microbial toxic concentration (MTC). The most significant potential of the test is in the additional inference that can be conveyed to the toxicity evaluation because of the presence of each of the constituent species. The performance of MARA was evaluated to ascertain its capability and potential scope in an intralaboratory trial. Sensitivity to toxicants and different environmental samples was assessed. Evaluation included comparison with other tests; namely Microtox, invertebrate (Daphnia magna and Thamnocephalus platyurus) microbiotests, and respiration- and nitrification-inhibition tests. MARA's performance was further assessed with the implementation of an international interlaboratory trial. This involved the participation of 13 laboratories ranging from academic establishments to regulatory agencies. The results of the testing will be presented with assessment of the extent of variability and specific assay components. The trial evaluation indicated that performance of the assay was satisfactory and the results were within the acceptable range. MARA is a robust multispecies assay offering scope for toxicity assessment of a diverse range of samples.

Equal channel angular extrusion has been used to deform an Al–3 wt-%Mg alloy to an effective strain of 10, resulting in a 0.2 µm grain size. In the as deformed condition the yield strength was increased to ∼500 MPa. During annealing the grain structure coarsened uniformly and the yield stress was found to follow the Hall–Petch relationship, even in the submicron range. There was an abrupt transition in elongation at a grain size of ∼0.5 µm. Samples with smaller grain sizes showed no uniform elongation and limited ductility. For slightly greater grain sizes there was only a relatively small reduction in elongation, compared to a coarse grained material, while the yield stress was still increased by a factor of over four. Reducing the grain size to the submicron range led to far higher Lüders strains than are normally observed in Al–Mg alloys.

Conventional culture for the detection, enumeration and identification of micro-organisms has been the traditional tool of the microbiologist. It is, however, time-consuming and labour-intensive and confirmed results often require several days of analysis. Culture may not grow the organisms being sought and for enumeration may only detect a small proportion of the total population. However, it does have the advantage of being simple to use and relatively inexpensive. It is also a direct means of assessing cell viability. Novel fluorogenic dyes and fluorgenic and chromogenic substrates have overcome some of these problems by providing a means of rapid and specific detection and enumeration whilst removing the need for subculture and confirmation tests. Immunological tests such as ELISA have significantly reduced analysis time by providing specific target organism detection. Molecular techniques have removed the need for culture. Improvements in sensitivity, and removal of the inhibitory nature of sample matrices, have allowed analysts to detect low levels of micro-organisms but the questions of viability and comparability with cultural techniques still remain. Are we about to see a change of culture in water quality assessment, or can cultural techniques be developed that reduce analysis time to a few hours and can rapid methods be used for detecting the presence and viability of organisms?

This paper describes a novel method of electrolytic colouring of anodized aluminium, whereby a wide range of coloured finishes can be produced. The method makes use of optical interference effects ...

Al-Zn-Mg alloys become embrittled during exposure to moist environments due to hydrogen penetration of grain boundaries. The result of this hydrogen penetration due to surface reaction with water vapour of both bulk specimens and electron-transparent “thin foils”, has been studied at high resolution in the JEM 100 C transmission electron microscope as a function of alloy composition and ageing treatment. In bulk specimens of alloys solution-heated, water-quenched, and aged in water-vapour-saturated air at 70° C, the hydrogen is in the form of a mobile atomic species which is transformed to bubbles of molecular hydrogen under the action of the electron beam. However, in electron-transparent specimens of aged alloys after exposure to water vapour the accumulated hydrogen is observed directly as bubbles. These bubbles take the form of hexagonal lenses bounded by {111} planes, and are associated with grain-boundary precipitates, particularly in over-aged microstructures, and with primary intermetallic particles in alloys containing sparingly soluble transition elements. The consequence of the observed hydrogen penetration of grain boundaries in promoting environmental debilitation of mechanical properties and stress-corrosion cracking of Al-Zn-Mg alloys is discussed.

Abstract A photocolorimetric method has been developed for the determination of small quantities of inorganic iodide in the presence of organically-bound iodine. The iodide-containing solution is treated with a mixed iodate-starch solution at an appropriate pH, when a stable blue colour is produced. The relationship between concentration of iodide and optical density is linear. The effect of various salts on the reaction has been investigated; the analytical application of the method to some iodine-containing drugs and pharmaceutical preparations has been studied. The reason for the failure of the colour reaction to obey Beer's law is discussed.

Abstract Benzhydrol, an impurity in some samples of cyclizine hydrochloride, interferes with the colorimetric estimation of ergotamine in preparations containing ergotamine tartrate and cyclizine hydrochloride. A method for overcoming this difficulty is described. The inhibition of colour development has been utilised to provide a method for the detection and estimation of benzhydrol in cyclizine hydrochloride.