 In the continuation of the previous module about the sterilization kinetics, we have one Arrhenius equation. So, if we combine that Arrhenius equation with the equation which we achieved by the integration of that equation. So, you can see here. So, we have in that module this equation ln of n t over n naught is equal to minus k t and k is equal to a is Arrhenius constant e powered by e over r t. So, if we combine these two equation then we have this equation. So, if we put just the value of k this value then we have this kind of the equation. So, by you can easily see that a dot e and then this is the. So, according to the D endoropher and Humphrey 1959 they use the term for ln naught over n t as design the criteria for the sterilization. So, that factor they called sometime they called as the del factor or nubbler factor or sterilization criteria. So, represented in this del factor or nubbler factors or a sterilization criteria by this sign. So, this sign is commonly known as del factor nubbler factor or sterilization criteria. So, we will use in later slides as a del factor. So, the del factor is the measure of the fraction reduction in the viable organism counted here we can say that count produced by the certain heat and the time regime. So, then the del factor if we say that del factor is equal to the this one then our del factor is equal to ln is into n naught over n t. So, this is basically show the fraction reduction in the viable organism with respect to the heat and the time of heat treatment. So, as we have this equation l and then we have this k t is equal to a dot t over this then the delta factor is this one. So, on rearranging the above equations then the equation will be l and t is equal to e over r t plus ln del factor over a that is known as Arrhenius constant. So, the plot of the natural logarithm of the time required to achieve a certain del factor value against the reciprocal of the absolute temperature that will yield a straight line. So, the slope of which is dependent on the activation energy you can see this whole relationship in this slide. So, when we draw the graph between the log of nature of the time with the temperature which we called as absolute temperature. So, then we can see from this figure. So, the degree of sterilization which we called as the del factor obtained over a wide range of the time. So, if we have a different time pattern then we can say we have a 2.3, 4.6, 23 and 69.6 these are the different del factors with respect to different temperature. So, this graph actually show the effect of sterilization and the temperature on del factor achieved during the process. The kinetic description of the bacterial death enables the design of the procedures that given to the certain del factors. So, by this way by choosing the value of n t then the procedure may be designed having a certain probability of achieving the sterility based upon the degree of risk. So, that whole degree of sterilization and the degree of risk that totally depend upon the del factors. So, in later module we will discuss this del factor in detail.