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MICROBIOLOGICAL ENGINEERING - ANSWER 28.1 : (a) Dilution = (final volume of mixture) / (initial volume of mixture). First dilution = ( 0.2 + 1.8 ) L / (0.2 L) = 10. Second dilution = first dilution x ( 0.2 + 1.8 ) L / (0.2 L) = 10 x 10 = 100. (b) 100 microlitres = 100 microlitres x 1 mL / (1000 microlitres) = 0.1 mL. CFU / mL = (number of colonies x dilution) / (amount plated, in unit mL). In the first plate, CFU / mL = 250 x 10 / 0.1 = 25000. In the second plate, CFU / mL = 23 x 100 / 0.1 = 23000. Average CFU / mL = (first plated value + second plated value) / 2 = (25000 + 23000) / 2 = 24000. The answer is given by Kang Chuen Tat; PO Box 6263, Dandenong, Victoria VIC 3175, Australia; SMS +61405421706; chuentat@hotmail.com; http://kangchuentat.wordpress.com.

Question 75 - The molecular weights M in kg / mol of 3 different monomers a, b and c in a polymer are Ma = 14, Mb = 16 and Mc = 18. The fraction of polymer chain X of 3 different monomers a, b and c in a polymer are Xa = 0.5, Xb = 0.3 and Xc = 0.2. (i) Calculate number average molecular weight by using the formula Ma Xa + Mb Xb + Mc Xc. (ii) Calculate weight average molecular weight by using the formula (Ma Xa Ma + Mb Xb Mb + Mc Xc Mc) / (Ma Xa + Mb Xb + Mc Xc). (iii) Calculate the polydispersity by using the answer in (ii) divided by answer in (i). (iv) If the molecular weight of repeat unit is 12, calculate the degree of polymerization by using the formula (Ma Xa + Mb Xb + Mc Xc) / (molecular weight of repeat unit).

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Question 111 - There are 6 spin orbitals in p subshell in a ground state carbon atom. Only 2 electrons fill the p subshell. Number of different ways for n electrons to occupy the k spin orbitals are k! / [ (n!) (k-n)! ]. Find the number of different configurations of electrons to occupy the p subshell in a carbon atom.

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Question 88 - In the calculation of the growth of bacteria, colony forming unit (CFU) in serial dilution is used. In a laboratory, viable count assay is used to estimate CFU. Formula applied is CFU / mL = (number of colonies x dilution) / (amount plated, in unit mL). Acceptable plate count is either between 20 and 200 or between 30 and 300 according to 2 different references. A wastewater sample of 200 ml is added to and mixed with 1.8 L of sterile water. Another 200 ml of the mixture is added to and mixed with 1.8 L of sterile water. (a) Calculate the dilution of first mixture and the dilution of the second mixture. (b) 100 microlitres of wastewater samples from the first mixture and the second mixture are placed separately on 2 different alga plates. The first plate has 250 colonies and the second plate has 23 colonies. Calculate the average CFU / mL.

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what are the major problem comes in the production process

2 Answers   Atul, Deepak Fertilisers,

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why sphericle shaped vessele used for storage of petrol?

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What are the affinity laws associated with dynamics pumps?

1 Answers   HPCL,

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ENGINEERING PHYSICS - EXAMPLE 30.2 : The Planck-Einstein relation connects the particulate photon energy E with its associated wave frequency f to produce E = hf. Let h to be the Planck constant. The frequency f, wavelength L and speed of light c are related by E = hc / L. With p denoting the linear momentum of a particle, the de Broglie wavelength L of the particle is given by L = h / p. (a) Find the equation of E as a function of p and c. (b) If E has a unit of electron-volt and f has a unit of 1 / second, then what is the unit of h?

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Question 91 - In the application of Theory of Spectrometry in spectrophotometer, let n = N x C x V, V = A x t, e = a x N where n = number of molecules, N = Avogadro's number, V = volume of cuvette, A = area of cuvette, t = thickness of cuvette, C = concentration of fluid in the cuvette, e = extinction coefficient, a = effective area of molecule. (a) By using calculus in dI = -I x a x N x C x dt, prove that ln (I / Io) = -a x N x C x t, where dI is the small difference in I and dt is the small difference in t. I = intensity of light. Io = initial intensity of light. (b) Show by calculations that ln (Io / I) = e x C x t based on the answer in the previous question (a). (c) Find the equation of log (Io / I) as a function of e, C and t based on the answer in the previous question (b).

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CHEMICAL MATERIAL BALANCE – EXAMPLE 2.2 : Three hundred gallons of a mixture containing 75.0 wt % ethanol and 25 wt % water (mixture specific gravity = 0.877) and a quantity of a 40.0 wt % ethanol - 60 wt % water mixture (specific gravity = 0.952) are blended to produce a mixture containing 60.0 wt % ethanol. The specific gravity of a substance is the ratio of density of a substance compared to the density of water. The symbol of weight percent is wt %. (a) Estimate the specific gravity of the 60 % mixture by assuming that y = mx c where y is wt % ethanol, x is mixture specific gravity. Values for m and c are constants. (b) Determine the required volume of the 40 % mixture.

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How does hollow shaft impeller works? Does it based on principle of pitot tube?

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Explain what are the problems that are associated with the expansion joints?

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Can you pls tell me how to calculate the amphere rating of cable in case of three phase supply but all load is single phase

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