Decay minimise

These considerations are included here because in the discussion that follows HC1 decay will be ignored, to facilitate the calculations. HC1 decay is also important when measuring PVC toxic potency, because the walls of exposure chambers are made of non-sorptive materials, where such decay is minimised. In this connection it is worth pointing out that the highest concentration of HCl found when fire fighters entered buildings actually on fire was ca. 280 ppm [25, 26]. 

Many wastewater flows in industry can not be treated by standard aerobic or anaerobic treatment methods due to the presence of relatively low concentration of toxic pollutants. Ozone can be used as a pretreatment step for the selective oxidation of these toxic pollutants. Due to the high costs of ozone it is important to minimise the loss of ozone due to reaction of ozone with non-toxic easily biodegradable compounds, ozone decay and discharge of ozone with the effluent from the ozone reactor. By means of a mathematical model, set up for a plug flow reactor and a continuos flow stirred tank reactor, it is possible to calculate more quantitatively the efficiency of the ozone use, independent of reaction kinetics, mass transfer rates of ozone and reactor type. The model predicts that the oxidation process is most efficiently realised by application of a plug flow reactor instead of a continuous flow stirred tank reactor. 

Murrill<5) has pointed out that the /t decay ratio constraint upon which the previous methods are based has disadvantages, e.g. the decay ratio is determined from the first two peaks and a comparison of the second and third peaks may yield a different result. Since a perfect response would correspond to there being no error at any time, some criterion based upon the minimisation of some function of the total error under the response curve would be logical. Three such functions are commonly employed, viz. ... 

The decay law G(t) was extracted from the experimental decay curve using nonlinear least-squares iterative reconvolution. The parameters were varied until the xl values were minimised and initially the trial function for G(t) was chosen to be a sum of 10 exponential terms viz... 

Prevent or minimise further decay Complete sterility of artefacts... 

The repetition rate of Ti Sapphire lasers is fixed by the resonator length. Rates from 78 to 92 MHz are common. The high repetition rate helps to minimise classic pile-up effects in TCSPC measurements. However, it can cause problems if fluorescence lifetimes longer than 3 or 4 ns have to be measured, since the fluorescence does not decay completely within the pulse period. Data analysis can account for incomplete decay to a certain degree. However, if the lifetime becomes equal to or longer than the pulse period, the accuracy of the obtained lifetime degrades. The pulse repetition rate must therefore be reduced by a pulse picker. 

The top shield includes roof slab and two rotatable plugs. Warm roof concept is adopted for top shield to minimise sodium deposition in the annular gaps. The roof slab is a box type structure filled with concrete as the shielding material. It supports the main vessel, primary sodium pumps, IHX, and direct reactor heat exchangers (DHX) of the decay heat removal system. Use of liquid metal seals has been avoided in order to reduce the rotatable support... 

A Tl weighted sequence has a short TE and TR. The TE is kept as short as possible to minimise T2 signal decay and keep the Tl as pure as possible. These sequences are reasonably quick to acquire. Most tissues have relatively long Tl recovery times and so are of low signal intensity on Tl weighted images including water and musde. 

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