Friends, let us summarize what we learnt in the last lecture. We looked at catalyst deactivation, we defined what is catalyst deactivation, what is the activity of the catalyst, which characterizes the catalyst deactivation. We looked at different methods or different strategies or different ways by which catalyst can get deactivated. For instance, we looked at sintering slash aging process, which occurs because of long term exposure of the catalyst to the gas stream and the reactants. Then we looked at coking or fouling, which predominantly occurs because of the deposition of carbonaceous material, when there is a catalytic reaction that involves hydrocarbons. Then we initiated discussion on the poisoning of catalyst, which primarily occurs because of the poisons, which may be present in the feed or the reactant or the product itself may act as a poison. So, we started discussion on the strategies to characterize poison when it is present in the feed. So, let us continue with that. So, a good example of that is the presence of sulphur or lead in the petrochemical feedstocks, which actually acts as a poison for the catalyst. So, example are sulphur and lead, which may be present in the petrochemical feedstocks. So, poison actually competes with the reactants for the catalyst side, with reactants for catalyst side. This is because the poisoning process can actually occurs simultaneously along with the catalytic reaction. So the active sites, which are available for the reactants to go and adsorb onto the catalyst side and continue with the catalytic reaction, the poison also in a similar way is ready to go and bind itself, adsorb itself onto the catalyst side. So, therefore, it actually competes with the reactants for the available free active catalyst side. So, this poses a strong competition for the reactants and that determines the extent of the deactivation of the catalyst. So, let us look at this cartoon. Suppose if there is a reaction A going to B plus C, heterogeneous catalytic reaction. Now if the catalytic sites, suppose if these are the active catalyst sites, which are present at time t equal to 0 in the catalyst and after the reaction starts proceeding and if these are the catalyst sites at time t1, which is greater than 0, then the sum of these sites may actually be, some of the sites will be containing the species A, which is adsorbed onto the surface, so species A and some other sites may be containing the poison, which is present in the feed steam. Suppose if P stands for the poison, then this site may be contaminated with the poison, that is the active site is now blocked with the poison, which is adsorbed onto the active site and maybe some other site may contain species B, which is basically the product, which is formed because of the catalytic reaction. Now if I look at further larger time point t2, which is greater than t1, then you will have many more sites, which are actually filled with the poison. So we will have many other sites, which are filled with poison P and therefore the number of active sites, which are available for the reactant species to go and adsorb onto the active sites for the catalytic reaction progressively decreases. So if I look at further larger time point t3, which is greater than t2, then pretty much all the sites, all the active catalytic sites are now occupied by the poison, which is present in the feed and therefore the catalyst is completely deactivated at this time point t3. So it is very important to characterize how this deactivation process occurs because the catalyst normally used in the catalytic reactions are very expensive and they cost a million dollars and therefore it is, if one can avoid the poisoning of the catalyst then it saves a lot of money for the industry and therefore and also it helps in maintaining the certain desired conversion, which is required for, which is desired by the company. So therefore let us look at what are the different mechanisms that capture the poisoning process and deduce the rate law, which governs the poisoning process and try to incorporate that into the reactor design and this has a strong implications in terms of how to avoid the poisoning process in the reactor. So let us consider the reaction steps. So there are three steps, which is associated with this main reaction. So the first step is the adsorption step, where species A adsorbs onto the surface and A s is basically the species A, which is adsorbed to the catalyst site and then the species A, which is adsorbed onto the catalyst site undergoes a catalytic reaction and leaves out product B, which is again adsorbed onto the catalyst surface plus a product C, which goes into the gas stream. Then this product B, B.S, which is present in the, on the catalyst site gets desorbed and the product B goes into the gas phase and leaving one catalyst site vacant, one of the active sites. Now this particular reaction will typically have a rate law, which looks like this, which we have already seen in one of the earlier lectures. So if A is the activity of the catalyst, then the rate of consumption of the species A, because of this catalytic reaction per gram more of the catalyst per unit time is given by the activity of the catalyst A multiplied by the specific reaction constant and multiplied by the concentration C A divided by 1 plus the equilibrium constant for adsorption, desorption of species A multiplied by the corresponding concentration plus the adsorption constant for species B multiplied by the corresponding concentration C B. Note that the main reaction is assumed irreversible here. Now the poisoning reaction, the poison which is present, suppose P is the poison which is present in the gas stream, which is fed along with the reactants, then this poison is now going to participate in a poisoning reaction which competes with the main reaction for the active catalyst site. So the poisoning reaction which occurs simultaneously along with the main catalytic reaction is as follows. So P plus S, which leads to binding of that particular poison on adsorption of the poison on to the active site. And the rate law, rate of the decay which is because of the poisoning of the catalyst active site is given by minus D A by DT that is equal to the specific decay constant KD prime multiplied by C P M multiplied by A to the power of Q, where C P is essentially the concentration of the poison in the concentration of P in the gas stream, that is the concentration of the poison in the gas stream. So in order to estimate, in order to find out the activity of the catalyst, we need to integrate the rate expression, but before that we need to estimate what is the concentration of the poison in the gas phase. So for that we can simply write, find out what is the poison removal rate. We can find out what is the poison removal rate from the gas and that provides a mechanism to characterize the dynamics of C P. So D C P S by DT which is basically the rate of change of the concentration of the poisoned active sites and that is equal to RP dot S and that is equal to the specific reaction constant multiplied by C T 0 minus C P dot S into C P. So this C T 0, C T 0 is the total active site concentration at T equal to 0 and C P S is the concentration of sites in which P is present, in which P is present, in which P is present that is P is adsorbed onto that surface and C P is the corresponding gas phase concentration. Now if we define a new variable F, which is essentially the ratio of the concentration of the sites onto which the poison is adsorbed divided by the total concentration or the total number, total concentration of all the sites which is present at before the reaction is started. When the catalyst is fresh then we can redefine this differential equation as D F by DT equal to K D into 1 minus F into C P. Now by definition the activity of the catalyst is essentially the ratio of the reaction rate at a particular time when the catalyst is used up to a certain time divided by the reaction rate as if it were a fresh catalyst that is when the catalyst is unused but which is exactly equal to 1 minus F. So therefore the activity of the catalyst A T equal to 1 minus F and so we can rewrite this equation as minus D A by DT that is equal to K D into A into C P. So this equation captures the activity of the catalyst as a function of the gas phase concentration of the poison and the reaction rate on the decay rate constant. So C P is a measurable quantity so if one can measure the concentration of the poison in the gas phase we should be able to estimate the dynamics of the decay of the catalyst. So let us look at how the catalyst activity changes in a packed bed reactor. So suppose there is a packed bed reactor and suppose if this is the inlet of the packed bed reactor and this is the exit of the packed bed reactor and if we want to look at the activity as a function of the weight of the catalyst at 0 when the gas stream does not enter the catalyst activity is almost 1 and at time T equal to 0 when there is no reaction the catalyst activity and all the locations is approximately equal to 1 because the catalyst is not used and so all catalyst which is present inside is a fresh catalyst so it should be equal to 1. At some other time T1 the profile would be like this so this is T1 greater than 0. So now some of these catalyst which is present near to the inlet of the reactor has now experienced reaction and therefore these catalyst will now start deactivating and so the initial part of the reactor catalyst will be deactivated significantly and then this is the activity profile that one would get. Now if I further look at some other time at T2 which is greater than T1 then this is the kind of profile you will get where the reactor is exposed to reactor is now used for conducting the catalytic reaction for a longer period of time and therefore the more catalyst starting from the inlet of the reactor would actually get deactivated and so that is the kind of profile that one would get and then similarly you can profiles for a much larger time T3 which is greater than T2 would like this would look like this and at a much later time T4 which is greater than T3 the profile would look like this. So therefore progressively the catalyst which is present inside the reactor will start getting deactivated and that is what is captured in this profile here. So next let us look at so far we looked at the poisoning that is caused by the poison which might be present in the feed. So let us look at the poisoning which is caused because of the reactants or the products itself. So remember we mentioned there are two different ways by which the poisoning can occur. One is because of the poisonous compounds which may be present in the feed stream. Another one because of the nature of the reactants or products which may itself become a poison for the active science. So let us look at the second case of poisoning by reactants or products. So the main so which means that the react suppose let us consider the case of reactants and the framework for if the product is the poison the framework is exactly the same. So let us specifically consider the case of reactant being a poison. And so the reactants are now adsorbing onto the catalyst side for two purposes. One is for the catalytic reaction to occur and another one is basically to poison the catalyst side. So therefore the main reaction the main reaction would be A plus S which is the catalytic side which will basically lead to adsorption of the catalyst onto the catalyst surface. Catalytic side and then A dot S would lead to B dot S plus let us say some C and similarly B dot S can get dissolved to form B in the gas phase and release a catalytic side. So this can actually be captured as A plus S essentially leading to B plus S. So now the poison the reactant because it also behaves like a poison it now competes with the main reaction in order to block the active catalyst side. So therefore the main reaction which is A plus S leading to B plus S whose reaction rate can actually be represented as minus rA prime equal to kA into CA to the power of N let us say for simplicity sake then the poison reaction there might be a poison reaction which basically is A plus S which leads to A dot S which poisons the catalyst side and let us consider the rate of decay is equal to kD prime into CA to the power of M into A to the power of Q. Let us assume that this is the decay law and a very good example of reactant itself acting as a poison to the catalyst is the case of methane formation using carbon monoxide and hydrogen on ruthenium catalyst on a ruthenium catalyst it leads to CH4 and H2O. So this is an excellent example of a situation where the reactant which is the carbon monoxide which goes and poisons the catalyst side. So let us try to characterize this process particularly for this example reaction. So if the rate of reaction is given by minus rCO equal to specific rate reaction rate multiplied by the activity as a function of time and multiplied by the concentration of the carbon monoxide and the decay rate law is given by minus DA by dt that is equal to rD which is the rate at which the catalyst gets deactivated and that is the specific rate constant multiplied by the activity multiplied by the concentration of the carbon monoxide in the gas stream. Now if we assume that the kinetics is separable so if we assume separable kinetics and if we assume that the poisoning occurs at a certain constant concentration so if the poisoning at certain concentration Cpo then we can rewrite the rate law as decay rate law as DA by dt equal to Kd prime into Cp0 to the power of n into A to the power of n and that is equal to some Kd so we can now club these two constants together we can club these two constants together into one constant multiplied in that is equal to Kd into A to the power of n. So if n is equal to 1 that means that the activity is given by exponential of minus Kd into t activity is given by exponential of minus Kd into t so this is exponential of minus Kd into t so that is the activity as a function of time of this particular case when n is equal to 1. So there are various types of decay law that have been proposed in the literature and some of these are various decay law so common one is the one where the activity actually linearly changes with time so that is given by minus DA by dt equal to some beta0 and when you integrate this expression we find that A equal to 1 minus beta0t so that is essentially a linear profile, linear dependence of the activity on time and this is actually this kind of a decay has been observed for conversion of para-hydrogen of tungsten on tungsten with oxygen as poison. So this kind of a rate law decay rate law has been observed for a reaction of conversion of para-hydrogen on tungsten with oxygen as the poison that deactivates the catalyst that is tungsten here. Another rate law that has been observed is the exponential rate law so DA by dt that is equal to beta1a and integrating this expression one would find that A equal to exponential of minus beta1 into t so that is an exponential decay with respect to time and this has been observed in the ethylene hydrogenation on copper catalyst with carbon monoxide as one of the poisons. So this exponential decay has been observed in the ethylene hydrogenation which is a very fairly well very common reaction, industry scale reaction and then the third type is minus DA by dt equal to let us see second order decay the order of decay reaction with respect to the activity is 2 and so the dependence of the activity on time is given by 1 by A equal to 1 plus beta2 times t and this has been observed in the cyclohexane dehydrogenation on the platinum alumina catalyst. In addition to these decay laws corresponding to independent deactivation the rate of deactivation can actually depend on the reactant or product concentration for example during hydrogenation of ethylene on palladium catalyst ethylidine formation may reversibly block the active sites. And then the fourth type fourth class of deactivation kinetics is basically a power law behavior so where A power n into A0 to the power of m where n is given by beta4 plus 1 by beta4 so that is the exponent and this while integration one gets the expression for A which is basically some constant A into t to the power of minus beta by 4 so it behaves like a power law of time and this has been observed for cyclohexane aromatization on nickel aluminum catalyst. So now we have found the rate law for we have characterized the different types of deactivation of catalyst and we have found the rate law and for each of these cases so let us try to now implement the incorporate the rate law in a reactor design so let us consider a fluidized CSTR let us consider a fluidized CSTR and let us assume that a gas phase cracking reaction gas phase cracking reaction where A goes to B plus C is occurring in this fluidized CSTR and let us assume that the feed contains a sulfur which is which acts as a poison for the catalyst and also assume that the cracking is a first order process cracking is a first order process and if we assume that the decay catalytic deactivation or decay of the catalyst is first order with respect to first order in activity and its first order with respect to with respect to concentration of species A in the gas stream. So now we can actually so the schematic of CSTR fluidized CSTR it looks like this where you have a fixed volume fixed volume for the CSTR it is well mixed and you have a feed which goes in and let us assume that CA naught is the concentration of the feed at the inlet and V naught is the flow rate volumetric flow rate of the feed at the inlet and CA is the concentration of the product stream or concentration of species A in the product stream and V is the volumetric flow rate with which the fluid stream leaves the fluidized CSTR. Now a simple mole balance can be written for this system so the mole balance is so the mole balance is the rate at which species enters the molar rate at which the species enters the reactor which is V naught into CA naught V naught has the units of volume per time let us say meter cube per time and the CA naught which is the concentration in moles per unit volume minus whatever rate at which the molar rate at which the stream leaves the reactor which is V which is the volumetric flow rate with which the stream leaves the reactor and CA is the concentration at which it leaves the reactor plus the rate of generation of the species A that is equal to the rate of change of the number of moles of A with respect to time which is the accumulation term. Now for constant volume which is true for a CSTR for constant volume the rate multiplied by rate in terms of the volume that is moles per unit volume per time multiplied by the volume should be equal to the rate defined in terms of the catalyst weight that is the moles of A reacted per gram weight of the catalyst per unit time multiplied by the weight of the catalyst so these two have to be equal. So incorporating this equality into the mole balance we can rewrite the mole balance as V naught into CA naught minus V into CA plus rA into V and that is equal to DNA by dt. Now DNA by dt can actually be written in terms of the concentration of the species and so that will be V into dCA by dt. So now the rate at which the reaction occurs that is the rate of consumption of species A is minus rA equal to the corresponding a specific reaction rate multiplied by the activity of the catalyst multiplied by the concentration of the species CA and the corresponding decay law is given by dA by dt that is equal to the decay constant multiplied by the activity of the catalyst multiplied by the concentration of A in the gas phase. Now if we know the rates of this reaction that is the reaction rate then next step we need to do in terms of designing the reactors we need to use the stoichiometry and relate these terms here. So using stoichiometry we can find that the volumetric flow rate of the stream that leaves the reactor divided by the volumetric flow rate of the stream that enters the reactor should be equal to the molar flow rate ft with which the species leaves divided by the it is the ratio of the total molar flow rate of the outlet stream divided by the total molar flow rate of the inlet stream multiplied by the p0 by p which is the total pressure at the inlet divided by the total pressure at the outlet multiplied by t by t0. So if at constant pressure if p equal to p0 and at isothermal conditions t equal to t0 so v by v0 simply reduces to ft by f0 ft0 which is nothing but 1 plus the net fractional change in the number of moles because of the reaction multiplied by x. So now the conversion x is equal to 1 minus fa by fa0 so that is the conversion and that is equal to 1 minus ca into v divided by ca0 into v0. Now remember that the reaction that we are looking at is a giving b plus c so therefore the net fractional change in the number of moles is given by the overall mole fraction of a multiplied by this change in the number of moles which is equal to ya into 1 plus 1 minus 1 that is equal to ya0 which is given by ca0 by ct0 which is the ca0 is the concentration of the species in the inlet stream and ct0 is the total concentration at the inlet stream. So by using this expression we can rewrite v by v0 as 1 plus epsilon minus epsilon into ca into v divided by ca0 into v0 which is and from here we can easily deduce that the volumetric flow rate of this stream that leaves the reactor should be equal to v0 into 1 plus ya0 divided by 1 plus ca by ct0. So now so plugging in all these volumetric flow rate expressions in terms of concentrations etc into the mole balance we can rewrite the mole balance as we can rewrite the mole balance After defining residence time tau which is the time that the fluid element depends inside the reactor which is given by volume of the reactor divided by the inlet volumetric flow rate and so the mole balance will be dca by dt that is equal to ca0 by tau minus 1 by tau into 1 plus ya0 divided by 1 plus ca by ct0 plus k into a into tau into ca and the activity is given by activity a can be found from the decay rate expression for the catalyst that is dA by dt equal to minus kd into a into ca. So these two equations essentially characterize the simultaneous deactivation and the catalytic reaction which is happening in the reactor and so if one needs to obtain the dependence of concentration on time and the activity on time then one needs to solve these two equations, solve the equation simultaneously and one should be able to obtain the concentration profile as a function of time and the activity profile as a function of time. So now we observed that the catalytic deactivation is a very serious problem because it poses a strong major problem in terms of maintaining the conversion of the desired products and as a result it has a strong effect on the economy of the company which is actually producing that particular product. So therefore it has a strong effect on the economics of that particular product and as a result choice of reactor is extremely important which will help in minimizing or avoiding the deactivation process. So the choice of the reactor, so what we are going to discuss now is to look at how can we use a particular choice of how can we decide what should be the choice of the reactor that will help in minimizing the deactivation of the catalyst and with the objective of maintaining the conversion of the desired product. So we know that deactivation and reaction they occur together, they occur simultaneously. So therefore the performance is severely affected and as an offset one could actually use different reactor configuration to maintain the conversion. So what we are going to discuss now is to look at what are the different types of configurations that one has to use in order to minimize the deactivation of the catalyst or rather in order to maintain the desired conversion. So suppose if the decay is very slow, so naturally the choice of the reactor and the necessary steps that one has to take depends upon the speed with which the catalyst gets deactivated. So if the decay is very slow then what really works is basically using a temperature time trajectory where the feed stream is constantly preheated and the temperature is increased slowly in order to minimize the deactivation and thereby maintain the conversion of the reaction which is happening inside the reactor. Suppose if the decay is moderate, it is a moderate decay then it is suggested to use a moving bed reactor and we are going to look at the design of this. So moving bed reactor can be used in order to minimize the deactivation and then if it is a rapid decay of the catalyst then one needs to use a straight through transport reactors. This classification is based on the deactivation time scales as dictated by the corresponding decay constant. So let us look at the slow decay, first case of slow decay. Suppose if the catalyst is decaying very slowly, so if it is a slow decay system then in order to maintain a constant conversion the strategy is to increase the reaction rate by slowly increasing the temperature, slowly increasing the feed temperature. So this by slowly increasing the feed temperature one could actually increase the reaction rate and thereby maintain the required conversion. And so the classical setup which helps in such kind of a design is basically a fluidized bed. In fact in many fixed bed reactors as well such as strategy is employed. Suppose if this is a fluidized bed, it is a fluidized bed reactor and then a preheater is added to a preheater is added to the inlet stream. So suppose the inlet stream is entering the preheater at certain initial temperature T0, then as the reaction proceeds the preheater constantly increases the temperature of the inlet stream so as to maintain a certain fixed conversion x. So which means that the reaction rate at T equal to 0 that is at the start of the reactor at the temperature T0 should be equal to the reaction rate at certain other time and certain other temperature T and in terms of using the rate law that we have derived for catalyst deactivation rate law for the reaction when the catalyst deactivation is simultaneously occurring. So that will be A into T, T. So now the activity is a function of both time and temperature and so minus rA into T equal to 0, T0. So these two quantities have to be equal in order to obtain the desired conversion. This quantity must be equal to this quantity in order to obtain the desired conversion in order to maintain the desired conversion. So now if we assume that it is a first order reaction, if we assume that it is a first order reaction and also if we neglect the concentration variations, if we neglect the concentration variations then we can write K of T0 into CA should be equal to the activity of the catalyst multiplied by the K that is the specific reaction rate at a particular temperature multiplied by the corresponding concentration CEM. So if we neglect the variations in the concentrations then we can write that K T0 should be equal to A into K of T. But we know from the Arrhenius dependence of the specific reaction rate that we can rewrite this expression as K into T0 that is equal to A into K T0 multiplied by exponential of EA which is the activation energy for that reaction divided by R into 1 by T0 minus 1 by T. So cancelling these two we can now find an expression that relates the local temperature that is the temperature at which the reactor is being operated with the activity and the temperature when the reaction was started. So 1 by T should be equal to R by EA which is the activation energy of that particular reaction into ln A minus plus 1 by T0. So this is the relationship between the temperature at which the reactor has to be operated and the activity as a function of activity and the initial temperature T0. So now if we look at the decay law which basically characterizes the deactivation of the catalyst. So if you look at the decay law so minus DA by DT minus DA by DT is given by K D0 multiplied by exponential of ED by R which is again the specific decay constant is also depends on temperature using the Arrhenius type expression into 1 by T0 minus 1 by T multiplied by A to the power of N. But we know using the rate law we can relate the temperatures using the expression 1 by T minus 1 by T0 that is equal to R by EA into ln A. So by substituting this expression we find that minus DA by DT that is equal to the specific deactivation constant multiplied by exponential of minus ED which is the activation energy for the deactivation of the catalyst multiplied divided by EA into ln A into A to the power of N. So this is equal to K D0 into A raised to the power of N minus ED by EA. So this expression provides a way to find out what is the dynamics of the activity as a function of time. Now if N is not equal to 1 that is the that is the order of the decay or deactivation as a function of activity is not equal to 1 then with assuming that the activity is 1 at time T equal to 0 the expression can be integrated and found that T equal to 1 minus exponential of EA divided by EA minus N into EA plus ED that is the activation energy for the decay divided by R into 1 by T minus 1 by T0 the whole divided by K D0 into 1 minus N plus ED by EA. So this provides this expression provides a relationship as to how the temperature has to be changed as a function of time. So this provides a relationship of how the temperature has to be increased in order to maintain a certain fixed conversion or desired conversion. Note that this relationship is valid only for independent deactivation. So this kind of an expression provides an industry operating person as to how much the temperature has to be increased or how much preheating has to be done in order to maintain the conversion of the desired products. So now if I look at the if I plot this as a function of time and temperature so this is the kind of profile that I will get. So if the catalyst deactivation is very slow then I can maintain the conversion by actually increasing the temperature of the gas that comes into the reactor and the kind of profile and the kind of temperature in raise as a function of time is captured in this graph here. So suppose if it is a first order decay process if the deactivation kinetics is directly proportional to the catalytic activity and if the exponent is 1 then the relationship between the temperature and the time at which the temperature has to be changed is given by ea divided by kd0 into ed multiplied by 1 minus exponential of ed by r into 1 by t minus 1 by t0. So that is the expression one would get and that sort of tells you what is the how the temperature has to be increased as a function of time when n equal to 1 that is basically the first order dependence of the deactivation kinetics on the activity of the catalyst. Now as a next step we look at what is the what kind of configuration that one has to use if the decay is moderate or a rapid deactivation of the catalyst. So if you look at the moderate decay case what is required here is because the deactivation is fairly quick, fairly rapid then there has to be a continuous regeneration or replacement of the catalyst inside the reactor in order to maintain a certain conversion, certain desired conversion of the products, certain desired conversion and therefore it is important to have a continual regeneration or replacement of the catalyst and there are two types of configurations, two reactor configurations have been used. So one is the moving bed reactor and the second one is the straight through, second one is the straight through transport reactor. These are the two types of reactors which is useful when there is a moderate or rapid decay of the catalyst which is used in the catalytic reaction. So the moving bed reactor in the way the moving bed reactor is basically a reactor where the catalyst is constantly replenished and the way the catalyst is replenished is suppose if this is the reactor, it is a cylindrical tube reactor, suppose this is the reactor and the feed to the reactor is provided from the top and the catalyst leaves the reactor and enters another chamber which is called a kiln and this is used as a regenerator, it is used as a regenerator which regenerates the spent catalyst which is deactivated and air is passed through this regenerator and once the catalyst is regenerated, the regenerator catalyst is circulated back, the regenerated catalyst is airlifted into another chamber which is called the separator chamber, so it is a separator into the separator chamber and once the catalyst goes into the separator chamber, it pumps the catalyst back into the reactor. So this is how the constant replenishment of the catalyst occurs in a moving bed reactor and this helps in maintaining the conversion and the products are removed from the bottom of the reactor. So the catalyst pellets that are typically used is about 1.8 inch or 1.4 inch, that is the typical size of the catalyst pellets that is used in these kinds of reactors. So now let us try to write model equations in order to characterize the moving bed reactor and thereby maintain the conversion of the reactants into products. So suppose if this is my reactor and if the catalyst enters the reactor at a rate of US, that is the mass of catalyst per unit time and if it leaves at the same rate, then one can write a molar balance and obtain an equation for the molar flow rate of the catalyst, molar flow rate of the species as a function of weight of the catalyst. So this equation molar balance actually captures the dependence of the molar flow rate on the weight of the catalyst and so this can be re-written as FA0 into dx by dw equal to minus rA prime. Now the rate of the reaction is now can be written as minus rA prime is equal to some activity of the catalyst A multiplied by the rate of the reaction at time t equal to 0. So therefore it can be written as A of t into the rate constant k multiplied by some function of the concentration CACB etc. And the deactivation kinetics is given by dA by dt is equal to the deactivation rate constant multiplied by A to the power of n. So let us assume that this is the decay model, this is the decay rate, that is the decay rate. This decay rate law is a simplified form and in general the decay rate can depend on reaction slash product concentration. And so the contact time needs to be related with the weight of the catalyst in order to characterize this particular reactor. So the contact time of the reactor, contact time of the catalyst t is given by w by us and from here we can estimate that at a differential time the amount of catalyst that enters the reactor is given by dw by us. So from here we can now rewrite the mole balance in terms of the, in terms of the catalyst which enters the reactor and also the decay rate law accordingly and the decay rate law is now given by dA by dt into dt by dw equal to kd divided by us into A to the power of n. And that is nothing but dA by dw. So that relates the decay of the catalyst as a function of the catalyst that is entering the reactor and dx by dw is given by A by fA0 into minus rA prime at t equal to 0. So one has to solve these two equations simultaneously, these two equations need to be solved simultaneously to obtain x versus the weight of the catalyst and A versus the weight of the catalyst. So that characterizes the moving bed reactor. So once we know this we can use this in design parameters in order to appropriately design the catalyst. So what we have seen in today's lecture is we have summarized the different types of deactivation of the catalyst that is sintering, aging, fouling or coking process and poisoning of the catalyst and we looked into the details of the mechanism of two types of poisoning. One is poisoning if the poison is present in the feed or if the reactant or the product itself acts as a poison. And then we looked at fluidized CSTR to incorporate the decay law which is based on the poisoning of the reactor and then poisoning of the catalyst and then we proceeded to look at what are the different reactor configurations have to be used because it depends upon the nature of the deactivation. If the deactivation is slow then one can use a temperature time trajectory reaction system and if it is moderate or a fast reactor one has to fast decay then one has to use a moving bed reactor or a straight through transport reactor. Thank you.


So Hello, and welcome. I Don't know how many of you know me, but in case you don't This is a little bit of background information about myself. I'm a software developer at Rackspace. This is a company in the United States Probably if you know me you don't me because of the the flask mega tutorial This is a series of articles that I wrote on my blog a few years ago that are somewhat popular I also wrote the O'Reilly book on flask Mostly these days I work on APIs and microservices and My language of choice Probably 90% of the time I'm coding Python, but sometimes I have no way to avoid writing JavaScript So I do and in previous life. I used to work a lot with C++ as well You have my my Twitter my My blog which has a lot of articles about Python in particular flask and my github Page where you can find a bunch of open source projects that I did Before I start I also wanted to mention the the other two Places I'm going to be available in this conference Tomorrow there's a training session a three hour long session on this specific topic on microservices So tomorrow morning That's that's when it's when this is happening and then I also going to do a help desk on Thursday If you have any questions about flask or web development or any of my open source projects I'll be more than happy to talk to you one-on-one. Okay so Basically, this is going to be an introductory talk on microservices probably intermediate level maybe a beginner that's ready to jump into this this Pool of intermediate yet that nobody knows exactly what it is But that that's basically the target audience So I'm gonna start with a set of analogies Imagine this is something that happened to me. I have a friend who was taking a So for development class he's not a developer. This was an elective Class that he took in college and he had to write a game game of pong He had a bug and he came to ask me for help and what he showed me his code it looked pretty much like this The whole game in a function So he called pong and then that that was the game and he had a bug with the way the ball moved Right, so so to help him I had to go understand pretty much the whole game Right, it was very hard for me to to figure out what's going on So I used the opportunity to show him a better way to structure this this game, right? So I told him you should do something like this Where you have a bunch of functions each function does one thing and then when when you need to do something bigger Than what a function does then you have a function that calls other functions and all the functions call each other and achieve The big thing that is the whole game, right? And I'm sure we all Going to agree that you know that the one the right is much better than the one on the left So here, but basically what we're saying that you know short and focused functions are better than long functions to do a lot of things Now what happens if if we go one level above? So this is this is an example from my book the flask book If you start the book it teaches you how to build a flask application and when you reach the end of chapter 6 You end up with an application that that does quite a lot But basically that the whole Python logic is in this this one module hello the pie Then you have a bunch of templates and a bunch of static files But but basically the whole Python thing is in 1.5 So so then you you're getting to chapter 7 and chapter 7 is the one that teaches you how to Structure your application so that it's more maintainable so so it goes into something like this where you have a Starter script managed a pie the configuration. It's in its own module You have the application is in a package and then the tests are in in a different package And if you keep looking the application has a Couple of modules that are for specific things. So the database models are in one module email Support is in another one There's this this main Folder, which is another sub package that is a What in flask? We call it a blueprint which for those of you familiar with Django will be sort of the same as a Django application And if you keep looking then you have for that blueprint you have errors forms and views So basically once again same thing as with functions now with modules We're saying that small and focus modules are better than large modules that do a lot of things right Now what happens if we take this even higher level and we talk about services web applications Well, can we translate this? So this is an example of a big web application This is actually an application that exists. It's on my github. I used this application to teach a class to demonstrate that flask can scale and Basically the idea with this application is that You have these two green boxes Flak is the name of the application and then the celery worker it's One or more workers that do asynchronous functions and the idea is that you can run Any number of flak instances and any number of celery workers and you scale those two according to your needs Then then you have a database that both use and there's a message queue That's used by celery and also used to to allow the celery workers to push Notifications to the client through through web socket So anyway, this is probably sort of an advanced ish application very scalable, but it's it's one code base so can we apply the same logic that we apply to functions and modules to this and In my opinion the answer is yes and Okay, first I should I should tell you about the problems with this So one problem that we have is that the code is a single code base. So it's Very hard to test all the things are Basically coupled you you have code that deals with users in this particular case Flak this example is a chat application So so you have coded these with users and messages all mixed up. You don't even realize that you are having You know coupling between those two Potentially separate functions of this application If you are working with the team and you need to introduce a new member to your team That person it's gonna have a hard time trying to figure out how to become productive because it you know that they'll have to understand a lot of things before You know before you let them participate You to reduce the risk of them breaking things In particular what when you use Celery something I find I find I don't like that much is that If you need to upgrade even though in this case we have two separate services the main service and the celery They all come from the same code base So there's no way to upgrade them separately you have to stop both or if you have many instances of each all All of that you need to stop then you do the upgrades upgrade the database Whatever else you need to do then you start them again. So so basically you have to take your application down for the upgrade Also if you have a problem and the application crashes Then basically the whole application crashes and the site goes down until you figure out what's what's going on and you can restart it The scaling becomes difficult Imagine in the case of a chat application like this So you have a module that deals with users a module that these with messages Very likely there's gonna be more activity on the messages side than in the user side, right?  So if you find that you need to to scale your application You're gonna be scaling the whole service. So you're gonna have you know that the necessary the necessary number of instances to satisfy the load for the messages But then you can also be having a lot of instances that can deal with users that are not there you're gonna be Over over scaling for the user side, and there's no way to have more fine control The only control is basically the the salary versus the rest the main service Also consider the case where let's say this is an old application you did it in Python 2 and now you are interested in going to Python 3 and That's gonna be probably gonna give you a headache right because it's all or nothing You're gonna have to upgrade the whole whole application in one go So all these are problems that are typical of what we call monoliths. So these big applications that are They're built with a single code base now This is also a real application. It's the same application. It's also in my github. It's converted to this idea of microservices and You can probably guess that the idea is basically to write Smaller services and the services then talk among themselves to achieve, you know, the whole function of the application And in this case, you can see we went from two green boxes to five and series not there anymore So so we have five services You can see in the bottom you can see the client UI. So this is a service that serves the application that runs in the browser For this particular case, I wrote that in Python in most cases, I'm going to guess that this is gonna be a node application and That's totally fine because you know, they're independent services. You can write each service with the best technology For that service. So we have a client UI. We have a service that is tokens That basically this is authentication Messages and users are separate services and then we have the socket IO service, which is the the web socket push notification Module so they're all separate in this case. These are all flask applications Some of these are so small that you can open them in your screen and see the whole code And the ones that you don't they're probably two screens not no more than that. They're they're all, you know, fairly small You can see that we went from two orange boxes we had a database and a message queue on the monolithic case now we have four boxes We still have the message queue that that serves the same function. It helps the Services communicate among themselves But then we have three databases. We have a database for the messages service Database for the user service and the database for the token service which stores provoked tokens And then what else we have we have a a new box a blue box called service registry I'm gonna talk about that more later, but basically this is a The very efficient database that keeps track of all the services that are running It knows what's running and then he communicates with the load balancer so that low balancer knows What what to you know, what the services are now These five green boxes. They're all Independently scalable now. So so now if I have more More load on the messages side I can run More more instances of messages and then keep users, you know at one or two for example so I Talked about You know disadvantages of the monolith and all of those now translate into benefits When we're doing microservices the code complexity it's it's you know, greatly reduced Each service as I said, it's a very small flask application You know reminiscing of the the hello world type application you see in documentation They're actually very simple to to code very simple to maintain Because we're forced to keep things separate it's less likely that we're going to introduce bugs due to coupling The user service has no way to access for example the messages database directly It needs to talk to the messages service so messages will have a public API that will expose to to clients or to other services the users will will do the same thing and Basically that that's a decoupled the sign, you know by force you're basically This design promotes the decoupled the sign that helps helps create programs to have less bugs now the the case of having a new member in the team that that you want to To make productive as soon as possible That that becomes really easy because you can put that person to work on one of your simplest services and Like in the case of pong if you have you know the the code structure with functions if I need to fix how the ball moves I don't need to learn how the You know how the players move or how the collisions happen all I need to do is Basically go to the function that moves the ball and this is the same thing you can put a new developer to work on the on the token services for example the token services is very simple and You know right away they take a start being productive You can you can even allow a new person to create a new service because it's a very simple application One of the things that I find most exciting is that you you can upgrade like the big guys do without Going down we never find out when Facebook Twitter, etc You know deploy upgrades because they do it, you know while running and we can do the same with this I'm gonna show you an example of that later probably you don't believe me, but you know Give me you know benefit of the doubt. I'll show you in a little bit If you have a problem with a service that crashes or has bugs or whatever That's gonna affect a small part of your application The rest of the application will continue to work So unless you're unlucky and your token service goes down which basically means that nobody will be able to authenticate If if you have a big application with lots of services and one minor service goes down Then the rest of the application will continue to work. So it's a partial Failure not not a complete failure that the case of a monolith I mentioned that you can scale individually the services and adapt to the loads and Finally also very important You can choose the best technology stack for each service They don't need to be all written in Python 2 or Python 3. They can all be written in the best tool And in the example of going from Python 2 to Python 3 if you started this application with Python 2 Then you could start migrating services one by one to Python 3 as long as the communication mechanisms between your services Is standard so you will do for example HTTP for example Then everything will continue to work and you can do a gradual upgrade to a new technology Likewise if you find that you need to write a new service and For some reason you find that go or node or Ruby is a best choice Then it's absolutely no problem. You can do that service in the in a different technology and that it doesn't really matter Of course, it's not, you know all roses and you know benefits. There are some some problems too What one problem that I see You know, I've enforced the fact that things become simpler This this is Really true, but not not so much The complexity doesn't go away completely The complexity goes into the if you look at the diagram it goes into the arrows So the complexity migrates from inside the green boxes into the arrows And now you have a web of connections that sometimes gets pretty crazy So you have to make sure that for example, you know have a cyclic Links a service calls service a call service B and then be eventually ends up calling service a again You know, you may need to look for inefficiencies in that sort of thing I Suggested by showing the boxes that each service has its own database So something that people like me which like relational databases a lot I suffer with being unable to do joins Because now each service has its own database So if you need to create a join in this example between users and messages, you have to do it in the application There's no way to use SQL because it's two databases and you know one service cannot access the database from the other And we don't want to To keep things separate and be able to upgrade the services separately Deployments are hard and you know, the Bob's people will tell you that You know, it's just security for for the Bob's people, but you know, there are so many moving pieces that Yeah, you know, it requires a full-time job sometimes to keep things going when we have this type of architecture and then finally You you have This this pinball effect right each service. That's small things So when the client requests a complex action, then that that may require usually requires a Request to pinball through different services, right? The entry service could be messages Messages may need to talk to tokens to verify the authentication It may need to talk to users to get user information They need to talk to socket IO to to push a notification to the client. So basically it becomes less efficient So you have to keep that in mind too. So response times for the client They're not gonna be as great as when you have a single code base So you you may wonder how do you go about? Transforming or converting or refactoring a monolithic application into microservices. Unfortunately, that's that's pretty hard and But basically there are the three main strategies They the one that's the probably the easiest is to say okay what I have so far. I'm going to keep I'm not going to worry about that, but then anything new that I start building from now on I'm going to build You know using small services microservices That's that's the easiest strategy not the greatest one because you still have a monolith that you need to grandfather into your microservices platform another option would be to To start with the big service Incorporate that but then over time you start breaking away parts of that big application Into small services. So eventually over time you are going to end up with a microservices architecture. That's a pure But but then there's gonna be a potentially long transition time where you will be You will be working with a hybrid That's probably what most people do When they do this and then finally you can you can use the line-in-the-sand approach and say okay I'm going to refactor this application into microservices, you know today It may take you a week or two weeks or a month, but then when you're done, then you have a complete application. That's You know that that's fully microservices enabled I Would something that's important and I see a lot of projects that they say, okay, I'm gonna do microservices and all they do they start writing services and that's probably I would say 50% of the equation You need to have a platform. That's proper for microservices to live and basically this if we What's Okay, if we go to the sorry if we go to the diagram This is basically the the load balancer and the service registry are very important components That that need to be in place even if you have a monolith that you are transitioning into microservices You'll have to figure out a way to incorporate that monolith Into the platform that allows microservices to exist. I'm not described what that means But Before I get into a little bit more theory I'm gonna do a demo and then if I run out of time then at least I get the fun part down So Okay, so this is this this this microflag application So I'm gonna show you Let's see so I'm gonna look in It's basically a chat application Please stand there so I can go to another tab You can see that things are look a half to bulbs That's probably example playing with this before So now I can Create another user You know so pretty simple stuff But let's let's look under the hood a little bit This is probably gonna be whoa. What's this? So this is An open source load balancer so that the the yellow The yellow box that you saw on the diagram on the left. It's called ha proxy Probably if you don't know this one, you probably know engine X Maybe you know traffic, which is another one. That's that's kind of becoming popular these days So all the these tools do is basically you tell them You know, where are your services and then you have clients connect to this thing and this is sort of a switchboard a control a traffic control that Basically shares all the requests that come from clients Among all your instances Now it this is super busy. I'm not gonna explain everything because it's irrelevant to our purposes here But if you if you look at the the sections there are six sections the top section basically shows you status about The this this tool H a proxy listening to requests. We're gonna ignore that There's five more sections and these these five sections are for the five services that we have these five green boxes You can see that Messages is running three instances. We're running version four Of the messages service and we have three so when requests come to this load balancer, they're gonna be assigned to one of these three and Basically, H a proxy would make sure that all three stay a more or less equally busy We have one of soccer area. We have two of tokens and then one of UI and one of users so you can see that I'm scaling independently So This is all running in a very great machine. So I'm gonna log in to show you some fun stuff so What I should say you probably used to hear microservices associated with You know platforms like a Kubernetes, you know that type of thing which you can use I'm not using that that right now This this is all, you know, I'm a flash by I like simple stuff So this is all built using bash and a little bit of Python So this platform doesn't use any, you know professional, you know professional grade Microservices platform. I have H a proxy. I have a service registry and then a little bit of batch So for example, I have a bash that runs a new service. I can say For example, it's let's run users Oops users So this this is gonna run a new container. This is all based on Docker containers So I'm running a second users. You are going to see in a little bit H a proxy please upgrade and show me to there you are So The the way H a proxy upgrades is a little bit clunky blanks the screen But that doesn't mean it goes down. It's just that the web Panel that that's a little bit clunky, but anyway, you can see at the at the bottom now. I have two users So all I did was run this I can show you Okay, this looks awful, but somewhere in here here at the top. You have the new this is the new users Container that I started so just by starting the container The container itself talks to the service registry, which is this database that that knows about everything and then The service registry knows about it and that that gets communicated to H a proxy So H a proxy puts that service online immediately now I'm gonna just be nasty here and I'm going to Kill that guy So the moment I stop it H a proxy is gonna notice that something's going not right. So it's gonna Blacklist that that service so immediately, you know, and any requests are coming. They're gonna go to the good one They're the other one, right and in a few more seconds since this isn't coming back, then it's gonna go away completely So this is one cool thing that you can do with microservices super easy You start and stop things I Mentioned before that upgrades are really fun and very efficient so As soon as this this red guy goes away. I'm going to show you that I have another another bash script That's that's going to upgrade messages. I have three there you go have three messages instances They're running before now on this instance. I have already here a version five That I'm about to deploy so I'm gonna say MF upgrade roll messages and Pay attention to what happens now So you are going to see a v5 messages come up please so So one v5 and now one v4 is going down Another v5 is gonna come and another v4 is gonna go down So so basically as you see there's always at least three That are running so we never stop we never have we never have less than three, which is what we intended that are running Eventually, you know the three v4s are going to be killed and they're going to be replaced by the three v5s We have one more that needs to go down There you go So that that's how you do an upgrade without stopping it. So I think at this time if If I look at these these two guys, they're still running Somehow I got two bulbs there, but other than that These these are still connected. They never lost the connection So so people using this service will never notice that you're doing an upgrade. Okay So that was a demo So in the time I have left Okay, not much Yeah, so five minutes in five minutes, I'm gonna try to rush through this I'm gonna describe the pieces that that make this that the build is So so we have a load balancer. I mentioned that I'm using a cha proxy Basically having a load balancer when you're doing microservices is a must you You can try to not use a load balancer, but it's really you lose a lot of benefits You you basically get to do very simple rolling upgrades I showed you a bash script that can do a rolling upgrade without going down And that's only because we have a load balancer that that supports this this architecture You can do a be testing green blue diplomacy all these cool things you hear the you know The very popular companies the fables the Facebook's and the Netflix is talking about they do the Chaos Monkey You know all those things you can do and and the load balancer is the main piece that supports this So super important that you have one in place before we before you start doing this the service registry is it's a database that usually It's designed to be highly available. You run multiple instances of it redundant and Basically super fast it caches stuff in memory so that you can you do queries are very quick and Basically the service registry is Basically connected from all the services when they start so they register themselves and then if the service dies The the connection depends on the system, but usually the connection Has a TTL so if the service doesn't refresh that connection and says hey, I'm still here Hey, I'm still here when stop saying that then the service registry will remove it And then immediately will talk to the load balancer and it'll remove it from the low balancer as well So basically that that's the whole magic and if you want to know I didn't put it here But the registry that I'm using is another open source project. It's called at CD et CD It's it's very simple. It's actually the one that Kubernetes uses as well containers are Big part usually you see microservices platforms are always done with containers. It's only because it makes things much more easy The container provides a layer of isolation a little bit better than just processes for example, it allows you to To work with virtualized network ports All these services that you've seen that these five services in the example That's all the instances of all these services they're all running on port 5000 Which is the flask default and and then docker takes care of you know mapping that into some other port that I don't even care Right, I don't care what port it is But but you know for me writing the services, it's for 5000 every time so that that's really nice You can do that yourself if you don't use docker, but you know, it makes things a lot more difficult And of course if you're using different different technologies Then having containers make sure that you don't have collisions between conflicting dependencies as well We have the orange boxes so storage your storage containers Usually your database your service registry can also be considered storage a message you you know all of those For all those for production platform, you will you will look for something that's highly available something that you can Make clusters off. So typically if you're using for example my sequel you you will look at Galera Which is a cluster solution or Aurora if you're on AWS, you know all those things that basically make the service very reliable Not running one instance that if it dies then the whole thing goes down, right? The same thing for cues and so on And then you have your applications. So these are the green boxes and these applications are stateless So I need to rush These are stateless. So that what allows me allows me to start and stop these services They have no data in them. They use the storage services to store data So this allows me to start kill and it doesn't really matter. They all are basically disposable I can horizontally scale them for free. I can run as many as I want And basically the more I run the more load I can handle on that service And I Think I'm going to skip this one in the spirit of saving time. I already talked about this Basically the lifestyle of the microservice it starts talk to the sir to the service registry And then when it dies stops talking to the service registry and that that translates into the load balancer removing it from from each configuration and Then finally we have service to service communication Which is the the mechanism by which the services talk among themselves this example I'm using HTTP as a way for internal communication There are many projects that decide to only use HTTP for for client communication into the into the project But then internally they use different mechanisms Which is totally fine as long as it is a mechanism that doesn't restrict your choices of technologies So you should find Standard RPC mechanisms, for example, that would be a very good way to to do a more efficient less chatty communication than HTTP So I'm gonna give you a link to the slides But if you want to try this example yourself you can just runs in a vagrant virtual machine These are the instructions and the requirements. You can run this application and play with it like I played here And tomorrow I'm going to talk in more detail about this if you want to learn how this was built You You can see the slides Thank you Thank you very much for this nice presentation. We do have time for questions Very close Thanks for the presentation My question is can there be a difference between running two Instances of the same microservice into docker containers on the same machine and running just one instance in one docker container So can it help with load balancing other cases when it can help? Well, I'm not sure if I understand your question, but typically you will not run Your let's say you have three instances You are probably gonna run them in different hosts and then the load balancer is gonna be You know in front of all those and the reason is that if the host goes down, you don't want, you know, all your instances to go down So there is no case usually when you would run to microservices into dockers on the same machine, right? I'm sorry. I Can't hear you well Should I I know you're asking about something specific, but Yeah, I mean can there be a case when we have two microservices in to docker containers and they are on the same machine Because they would have different processes and either a case when it could help Well balancing because It's totally fine. You mean if there are collisions between the two containers. No, I mean would it make sense in any case? What make more sense is to to use different hosts? Okay. Thank you That was my question. I mean only for for reliance, right? You you don't want, you know a host a docker host to go down and take all your instances of a service So you will have even different data centers, right? If you are, you know doing this for real Okay, thank you Any more questions Hi, thank you very much. I was wondering what's the best practice for up a rolling upgrade in microservices like it just did When one service it's changing the data scheme and the other one isn't Yeah, right so Yeah, I didn't expect to have time to talk about this but glad glad you asked there are some rules So when you make upgrades to the database that that's not the only case But if you make upgrades to the database, they need to be about what's compatible always The same thing with the API. So if your service a you know, your service exports an API that other services and clients use That if you make changes to that they cannot be breaking changes So in my example here when I went to before before to be five of a service I need to make sure that I can have v4 and v5 running at the same time using the same database So usually if you need to make significant changes to your database, you need to make them in stages You cannot make them like in one go. You cannot remove a column. For example, you can deprecate a column You know deploy the upgrade once, you know, you you're all upgraded only then when you make sure that No instances are using that column then then remove it in a second step It's more difficult. Yeah It's a pain actually Okay, one more question. I very interesting talk. Thank you I've got one question if you split up your big application into many that keep the data in different databases How do you keep your database backups consistent? How you keep you basically its services independent. So you you have to back up everything separately It can be in its own schedule. Yeah, they don't need to be done, you know at the same time or anything Okay, so it's you have to split up your transactions so that what has to be in one transaction has to be the same database then Okay, thank you Okay, we have time for one last question Hello So if you're upgrading your database, you were saying that the Instances of the microservices shouldn't have any data and they can be closed at any time But if you're upgrading the database, how do you? Maintain the data because the services shouldn't be holding this data Well, so yeah, but basically that's the same question before it's difficult You have to design your database upgrades so that they are that they don't break existing application that the existing version of the instance So typically requires multiple stage approach to make significant changes and usually you try to avoid making big changes Usually you add stuff but never remove or rename You know because those are kind of expensive to deploy You know because of all the effort and the risk of breaking something so so so yeah, typically you start thinking Probably now if you've never done it, it sounds crazy And I was in that same position a couple years ago But but then you get used to to that and then you start thinking in You know designing your database, you know so that you don't have to make You know breaking changes so often of course if you need to make a breaking change then, you know You can make an exception and say okay this time. I'm gonna stop everything upgrade and start everything and then there's some downtime You can go that route too Another option is to use not no sequel databases, which I you know, I'm a big fan. I'm all guys I'm traditionally trained. I like relational but I have to agree that you know for this type of architecture. No sequel makes a lot of sense You know because it's a lot easier. There's no schema to do to deal with Okay. Thank you very much. Thank you


Where's Mr. Arrow? Where's Mr. Arrow? What's Jimmy? Where's Mr. Arrow, Jimmy? Jimmy! Oh, that did it, right? Yeah! That did good!  Oh! Oh! Oh, the cool bladder! Oh! Oh! Oh! Oh! Oh! Oh! Oh! Oh! Oh!


I'm pleased to report that the Sports Pavilion application was received on, I think, Friday of last week. That is working its way through validation and hopefully will be out to consultation very shortly. The phase 2B is also progressing through having completed its consultation. Now, we're targeting, obviously, looking at whether there's any amendments needed, and obviously, in effect, targeting a planning committee to consider that, because it's been called in by Northsdale Town Council. And in terms of phase 3, again, that is progressing. We expect to progress to a decision later this year on phase 3. So, in addition to that, there are a number of condition discharges that are coming through and all those kind of things. And we are also starting work on the Town Centre concepts and ideas, which will come undoubtedly to this forum at some point. Thanks, Andrew. Dean, you want to cover up what happens in England? Yes, thanks, Chair. So just a quick update, and I'll try and avoid repeating what Andrew's just said. In terms of infrastructure work, the contractor's cysts are busy in the phase 2 water park. They'll be constructing some bridges over the next month that are part of the circular walk around the lakes. And the intention is that the phase 2 water park will be open in September. Wilson's Bridge, as people would have seen, is now installed and almost complete. Again, cysts are progressing, finishing work, either side of the bridge to allow the bridalway to reopen. The majority of the infrastructure work that cysts got undertaken due to be completed in September. So, in a couple of months' time, there might be some residual landscaping to be undertaken at the appropriate time. In September's date, we're also targeting for opening of the new access road. I've had some questions. I don't know if you want me to answer those now, Sarah, or? Yes. I had a question about the timing of the Town Centre delivery. We are about to seek a partner to deliver the first phase of the Town Centre, as Andrew just kind of touched on. We are hoping that building work will start mid 2023 and first facilities might come on stream summer 2024. That obviously depends on the number of factors such as getting planning permission. We have an inquiry about when, I think this is the Rampton Road Greenway, actually the section between the church and Rampton Drift. That requires closure of the road and re-routing. We've always seen that as a long-term proposal, still some way off 2030, something like that. The intention is to fully consult with residents before we do anything drastic such as close the road, clearly. The final one was around reversing alarms. There have been a number of issues with reversing alarms and starting and completing work out of hours, which we're aware of. The first thing is to apologise to any residents affected. We've been trying to identify responsible parties with a number of contractors and partners, subcontractors. We do continually remind them about the kind of limitations that are appropriate in terms of working hours and white noise, reversing alarms, etc. Most recently, there does appear to be some evidence of some out of hours work on the urban splash site. We've queried that with them. It appeared to relate to a specific circumstance. However, they have asked me to apologise on their behalf to any residents who might have been affected by that work. They've provided assurances that they won't conduct such activities going forward now that they've been reminded of requirements. I think that's it in terms of questions I've seen, Chair. Yes, there's just one additional on the chat to come through about Southern Access Road West connection to the roundabout, the B1050-A14 entrance. So there's discussions on going with Nigel and his team at County. We are hoping to have that available in September this year. Great, thank you. I think that's it for you for now. I've had a question, Andrew, on balancing ponds and the B10 cycleway, which are linked to north-east development, having not been progressed, and when will this, or do we have an update? I don't have a specific update. I don't want to throw a term under the bus as well, but that also relates to the delivery of the cycleway on the B1050 and those aspects. I am in discussion already with Longstanton Parish Council with regard to that, and also with regard to getting it all sorted. Just to be clear, the B1050, the Hatton Road ponds are not part of North Stowe, they are better meant to Longstanton and part of that journey strategy. So can I also say as well, if you've got enforcement issues, don't mind about it on Facebook, please submit them to us on the web. We're not out there monitoring Facebook, we've got enough to do. So yeah, if you want us to look into it or action it, then please either contact the councillors or, as I say, the enforcement website is there for people to submit complaints to. Thank you. And just to say thank you for those residents who have taken videos of our hours working because it is really useful for me to go and tackle developers with and show them proof that actually it's happening before hours of hours. So yeah, do continue to take those and submit them as if hopefully they're not happening anymore, but if they do carry on that we have that.


I dare him to dash at me, bro.  Never mind. I was all talk. I was all talk. I was all talk How's it going everybody? That's what I hear back with some more Dragon Ball fighters rank matches this time We are doing a suggested theme of a random team that I selected in training mode just a few seconds ago Here's how I reacted to each character pick by the way. All right. I don't know how I'm going to do this I think you guys already know what team I'm going to use But I thought I'd record my reaction to it anyway just so you could know how I'm feeling about the team So character one. All right. Hey, not too bad. I'm not gonna complain about this character, too Would have liked it better in season two, but let's be honest Super Saiyan Goku still solid definitely enjoying the new Season 3.5. Wow. He was still talking that whole time character three. All right Hey team Super Saiyan is not that bad to get the real test though is gonna be in the assist Which is really the only way I know is to just do a quick spin and let go Hey, I'll take it definitely not bad for Broly. Let's see if I can get what assist for Goku B that might actually be the worst That might be the worst Super Saiyan Goku is this and for Gohan, you know, I'll take A or C A or C Hey, okay, I'll take it So DBZ Broly up on point with a Super Saiyan Goku in mid with B and team Gohan on anchor with the ASS So that's right Even our assist were randomly selected or as randomly as I could make it probably the best way to go about Doing that would just be to use an actual random number. Did I pick the Halloween colors? Broly I you know what actually that's good. I mean, I got these colors last year I never since then they've been out of season, but now we're actually wrapping around to this being timely again So don't do H. Me. I know I deserved it, but I'm glad you didn't ooh The reflects love to see it block that we don't want to we don't want to get hit here I'm really trying to get out of this. Oh, right. We have the flurry kick assist I backed up to try to use the beam. All right, hold on. We got to get we got to get comfortable with the team Ideally, we probably want to switch Broly out. Never mind. You know what? We're gonna do it though We're gonna get team Gohan in here. I don't know how that assist works. What do you use that assist for? Is it like a yoncha? Oh? We barely made it through the Vegeta assist, but that was clean. I dare him to dash at me, bro I would kick him so never mind. I was all talk. I was all talk. I was all talk. I Was just a man. I was just talking. Oh wow so fast Not the overhead is that it for team? Wow four bars. Yeah, that probably is it for team go on unless we see an unfortunate drop fortune it for me He's overextending. He's trying to save all the bar he can and he did it. That was clean well executed Well composed. I hate to see it He probably loved seeing it though Gohan also got a level that was pretty clean and I'm using the easter color for goat man when people ask me Why don't pick colors? It's because I'm bad at it, dude I just am not good. I Think we want to leave Broly in the back for anchors. Plus. I think we got his a assistant. It's not bad I'm a switch though Let's see if Broly can't get us out of this mess We need at least we need to even it up to two characters to do and we might need spark to do it I'm not gonna stay here and get mixed. Oh Oh, maybe you know what? Hey, this corner has always been pretty comfortable to me I like the lush setting the tree the palm tree in the back has always been pretty cool to me Yes, slow it down a little bit. That was that works that gets it done a Couple of key blasts here and there Okay, we can kill with that. I can I'm definitely going to take that. All right, hold them down for Broly Broly will finish the job. Thankfully that worked could have gone really bad But we got that two-to-two scenario. We were hoping for he's probably gonna Super Dash soon There it is He was he did that last time we got to adjust to that he super dashed again though I did not predict that one did not predict that one and tried to jump away and got caught in the jumping animation Nice the rush down.  I Got up if you're not going for the kill. I gotta punish. Why are you saving seven bars? Man, this guy tried to save bar just to flex on me. I know I only got the one All right, let's see if we can't force him into a situation where he wants to Super Dash again This is about as similar to last time He did it last time he'll do it again Reflect and make him think that he needs to super shh. I wasn't ready for that one. I wasn't ready. Don't tell him that though There he is again. Oh Jack couldn't I we created the scenario, but I was never in a place to actually punish it That was on me. That's it. That's that's my bad. We got to go ahead and Dragon rush.  All right, that's fine. That's fine. If we work on we know what setting he likes to Super Dash in now Obviously, he might adapt But that's okay. If we can just get a few more of those key punishes And maybe not lose team go on as quickly as we did. Oh nice combo Off of the Vegeta was it Vegeta way is just really good by the way would not recommend sleeping on that one Didn't reach. All right. He's gonna Super Dash here. Remember. He likes that Super Dash He likes Super Dash in these scenarios. Oh, why am I trying to stand up and go for Larry? I need to get out of here, dude. I need to get out. I need to get out her heads I wasn't ready. I was too focused on trying to get out I'm still hoping that maybe they drop it. Nah, there's no drops here Dang, I was definitely hoping we'd get out of there in time. Not another level one for go on Whoo Goku can you get me out of here? I thought a nice vanish confirm He does like Super Dash here. I'm jumping too much. I'm getting caught on my jumping frames Gotta stay on the ground Stay on the ground. Stay cool. Stay calm. Stay cool calm collected sparking Vegeta I'll take it. That was so close. Do I have a jump? I did I'm trying to remember the Goku combo as we go along No big drop on my part Nice to age. I thought he'd get over confident with 17 there Off the drill Super Dash might be the move Goku's dead Vegeta comes out to we're not even oh no no go on's out. That's good We can at least pick up a quick kill if we're lucky.  That's fine. No It's not ready to fend bad game what unless he drops it I'm down taking and calling my father right now if he drops it you would see my father so fast You would have thought I was that kid on the playground Okay game one did not go so great game I wish we would have punished more. There's definitely a lot of missed opportunities in that set But I gotta give it up. It was a good game. We couldn't get it done Let's see if we can hopefully clean it up in the next set. Okay. We are back for a second chance Hopefully it goes a little better, especially considering we found another God of destruction rank opponent with a pink square to boot So there is a lot on the line for our team. We just got to prove ourselves I think we got to get Broly a little better. Let's go. That's how we need to start this off I'm gonna let team Gohan do the talking from here on out actually a little cheeky, but it gets the job done I'm I don't know what I want to do here. Yeah, I couldn't block there I was definitely thinking about going for DP, but we already got an early spark out of our opponent Which means we can go for one and feel pretty confident in it like right now. We definitely don't have to respect that I think I'll take it. Oh Barely dodged come here And you two hit remember that key blast game make them make them stop Obviously, I was a little scared considering it was UI Goku For now, I mean we might as well try to make him stop man that jumping light is so good Hold them down Goku. Give me some time. All I needed some time to get in there with some lights Let me get Goku out here in a different way actually help me out dad That's right. It's the father-son attack going low Didn't think that one would hit actually. Oh, hey nice speaking of it I did not think we'd be able to connect with that first one Zamasu, please. I know you have seven bars Don't spend it. You don't need to Didn't confirm off of that as well kick kick kick kick kick. No reflect. You've got to respect team Gohan I don't know why arxist wants you to but you have to That is so crazy that you can do that with to go on jumping light No reflect Broly's gonna come in cuz I just want to be oh got kicked in the gut for that. That was clean a little aggressive, but definitely clean All right, well hold on Hold on. We can't let him put his hands in his pockets every time Except for sometimes most of the time he can put his hands in his pockets if he wants No, I think we just broly him right here, right? Yeah, I don't think we got to think too hard Don't do any rejumps. Just do the broly stuff Give him a present and that's gonna get us our first win of the video Glad we could get at least one Now I would prefer if we could finish off with two Two would be much better the halloween broly. It's not actually I think it might actually be top tier halloween colors I don't know. I don't know all the halloween colors off the top of my head But I think for most characters it doesn't look too great for broly though. It looks all right The orange and purple it works. It works on them. Speaking of working. I'm just gonna raw heavy I didn't work for me that that one did not work for me But the overhead did time to set up my set boy I have a little bit of regret But not enough to stop me from just doing the broly things in life I just got to enjoy the simpler things the level ones Nice clean kill on ui goku. Can we make this? I don't know. I don't want to get to ahead of myself but reads I was definitely thinking like how long do I got to hold this before somebody does something Oh that would have been so sick if we ripped him out of the air like that Instead we're gonna get see oh wait a minute. He got combos. I was gonna say that was a pretty good extension off of c assist Let's see if we can't get the rejump. No, we can't even land the heavy But now we can I don't think that one was hitting Stop that. Stop that puny god Never mind. You're pretty imposing god. I should I shouldn't have talked. Oh, I died to the c assist Well, we still have spark. That's the big difference right now. Obviously in our health bar as well It didn't mean to side switch, but it should be fine Ah, panicking though level three Yeah, we're good. This is definitely gonna kill hit. Please.  Okay. He's definitely um He's tapping into some of that canon strength level three I think he wants me to spark here. So i'm not going to purely because I think I like my chances with team gohan Really good at that he's reacting That super dash was not too great, but it was really good of him to react like that I like my chances here though. You talk it. Oh, no. Did he just go behind me? Hit i'm getting tired of your canon strength. Please please downgrade back That one was in front of me. Damn we need this dude. He's got a counter Oh, no, come on. Please Why is hit such a problem character for me? No, you've got to at least give me that Oh, i'm not trying to get baited. I'm running out of sparking time I got caught. I didn't think he'd move in after that.  Oh my god. Why would he risk that? Wow, that was a button and a half That was max range Air to air that was stylish. I gotta respect it. Oh, I knew dude as soon as I saw full health greed hit I was like, yeah, this is gonna be a problem This is gonna be a problem for me Dang that was still good though I should have sparked with goku is what i'm thinking now. Oh, no. Am I gonna get cleaned up now? How the adjustment's been made and I gotta adjust myself I should have sparked with goku the two character advantage. I shouldn't underestimated that But we gotta we gotta stop focusing on the past. We got to worry about the present We got to worry about dishing out presents with broly All right, let me spark. He was ready for that It doesn't matter. I don't care who's ready for what. Oh, come on. I tried it with all level three That would have been clean.   Okay, and we don't have spark. So this is uh, not a great place to be But for some reason I feel more confident I feel confident for some reason Um, the confidence just really drained. Wow. He hit the release valve on that Confidence was looking pretty high. The storage was looking fill uh full And now I can't even speak that's that's about all you need to know about the state of the game right now goku getting messed up Oh the second half of that Nice Come on. I got to get that at least No No Ugh I knew we'd click buttons. The level three was the only thing I could do with any invincibility Super dash that was bad too many reflex. I try to get the hit c assist But after that I did one too many Seven bars that he's not even spending to This is a whole flex Here comes the spending you can actually hear the you can actually hear the cashier And the cash register. Wow. That was a big purchase I don't know what we're gonna do to come back from this, but it's gonna have to be clean It's gonna have to be a great game defensively Why am I going for the hard route? Oh, no, see this is why we don't go for that if he didn't go out should have gone with the light That was bad bad super dash c assist and he does get the combo great stuff He's got to spend a bar to kill, but he probably Yeah, he probably will Tingohan anchor saved me. Let's see. Let's see for some reason my confident Don't say it. I last time I said this it didn't work out like I wanted it to But this time I can't hide it the confidence is just blasting. I'm just gonna level five Nah, let's save too far.   You don't know. Okay. Okay. Hold on. Hold on Maybe I shouldn't hit that button when I hit that button, you know, it wasn't what it was It wasn't what it was no if he got that hit that was it The assist was clutch Mess up. No, there's no mistakes being made here. Oh the hit comeback stopped us in our tracks clean Dang, I gotta give it up. That was impressive Clutch the fist Oh Ultra it's come on Goku. Let's be honest. That was a good game Oh, hopefully you guys enjoyed that one if you did definitely let me know down below in the comment section As well as any suggested teams you have and make sure to like button and subscribe to the channel If you enjoy the videos you see here and want to see even more speaking of seeing even more There should be some more videos on your screen right now. So check those out if they catch your eye I have been Datsudoi though. Thanks again for watching and I will see you in the next video


Hello, I'm Dr. Judy Aschner, physician-in-chief for Hackensack Meridian Children's Health. In today's environment, parents may be concerned about seeking health care for their kids, but it's important to remember that wellness visits and up-to-date immunizations are vital to a child's health. To prevent the spread of infection and keep you and your child safe, we've implemented new procedures such as temperature screenings, wearing masks, and rigorous cleaning. Virtual visits are also available. Visit hackensackmeridianhealth.org slash getcare now to learn more.


My name is Melissa Kapulu. I'm a post-doctor research scientist based at the Kimiwokam Trust Kilifi campus. My area of research is based largely on malaria and looking at immunology, transmission dynamics and epidemiology and largely focusing on immunopidemiology of transmission stages as well as establishing platforms and models that can be used to interrogate immunity. So broadly speaking human infection studies in the last 5 to 10 years have largely shifted to lower middle income countries. These are studies that have largely been undertaken in naive populations in developed countries and there is now need to set up these models in endemic regions. And the reason for this is that with endemic regions there is naturally acquired immunity or pre-existing immunity. Body of knowledge that has grown in the last even 20 years is that when a vaccine is developed, let's say for instance in the United Kingdom or in the US, it is tested to look at efficacy in human infection studies in the US in a naive population. It will give very great results of maybe 60 to 80 percent efficacy. As soon as that vaccine then moves to an endemic population, the vaccine efficacy dwindles. It wanes and it can be anything between 10 to 50 percent. So that in there are modulating circumstances based on the fact that individuals are exposed to a plator of illnesses including the actual vaccine disease target. So it is very important that during the development pipeline of a vaccine for instance, you do actually look at efficacy within the setting that that vaccine will be used. So in our case we've established the human malaria infection model to look at naturally acquired immunity because that is key to understand how immunity develops in the context of for instance, past exposure. And that will give us answers on what potential correlates of protection one can garner when you're looking at various vaccine targets. In addition to looking at potential correlates of protection, you can also look at potential other secondary targets that you can then develop into potential second generation vaccines. One would ask a question, why does this matter? Why invest time, effort and money into this? This is important. It matters because it builds capacity in the local context. It matters because it provides establishment of key scientific findings, establishment of key scientific processes happening in lower to middle income countries. This is very key if we're going to have a situation where solutions are coming from areas that are actively affected by these disease processes. And it is key that scientists in areas that are affected play a role in coming up with solutions that could benefit not just the local context, but even the wider context. I believe in strong collaborations between North and South and South and South. Therefore, the fact that you would be able to establish such type of studies in a South setting comparably with a North setting is very important. It builds capacity. It builds knowledge base. There's a lot of insights we can gain by doing these studies in settings like in the South. And also it allows for integration of scientific thought, integration of scientific processes that would otherwise not organically happen if there was no investment in effort and time in setting these studies up in areas that are important. My research and my research interest fit in broadly and widely in translational medicine. I feel that I am at the more or less the bridge between basic science and translational science. What we gain from insights in chopping up a mosquito in the lab to look at whether it's got parasites will have an effect on how that then gets translated into whether you're going to test an intervention in that particular mosquito strain. So I believe that in broad and as well as narrow terms, in terms of translational research, that is a whole process which encompasses both basic as well as moving into translational research. So for translational medicine to come up with potential correlates of protection, potential targets for vaccine development, potential models and mechanisms to test various interventions, that is really key in trying to translate our science from the bench to the field.