MICROBIOLOGICAL ENGINEERING - QUESTION 28.3 : In the calculation of the growth of bacteria, absorbance, A in spectrophotometry is used. According to Beer-Lambert Law, A = e x l x c where A is the absorbance of the solution (no unit), l is the distance of light travels through the solution (in cm), e is the molar absorptivity or the molar extinction coefficient [ in L / (mol.cm) ]. For a particular solute and fixed path length : As / Ao = Cs / Co where Ao is the observed signal for a known concentration Co, and As is the observed signal for a sample concentration Cs. (a) For a cell concentration of 560 cells / mL, a spectrophotometre gives an absorbance reading of 1.0. A mixture of concentration 3600000 cells / mL can be diluted in several operations, with each operation having a dilution of 1:20. How many dilutions should be made so that the concentration of this mixture can be calculated within a range of A = 0.0 to 1.0. (b) In another experiment, a sample tube of 1 cm in width is used. Let A = 0.06 and e = 0.0012 ml / (cell.cm). Find the cell concentration of the sample.
- 1 Answers
- 1702 Views
- I also Faced
- E-Mail Answers
MICROBIOLOGICAL ENGINEERING - ANSWER 28.3 : (a) Let Ao = 1.0, Co = 560 cells / mL, Cs = 3600000 cells / mL. By using the equation As / Ao = Cs / Co, then As = Ao x Cs / Co = 1.0 x 3600000 / 560 = 6428.57. For a dilution of 1:20, first stage dilution gives A = 6428.57 / 20 = 321.43, second stage dilution gives A = 321.43 / 20 = 16.07, third stage dilution gives A = 16.07 / 20 = 0.8, which is within a range of A = 0.0 to 1.0. Total stages of dilution needed = 3. (b) By using the equation A = e x l x c, then c = A / (e x l) = 0.06 / { [ 0.0012 ml / (cell.cm) ] x 1 cm } = 50 cells / mL. 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.
| Is This Answer Correct ? | 0 Yes | 0 No |
Mention some of the specialized crushing methods?
What is the chemical name of Silica gel?
Corenuts technology interview questions
Please tell me what type of questions will be asked in a petrochemical company
ENVIRONMENTAL ENGINEERING - QUESTION 22.3 : A well delivers 225 US-gallons per minute of water to a chemical plant during normal system operation. (a) Calculate its flowrate in the unit of mega US-gallon per day or MGD. (b) The following formula is written next to the chlorine feed point : (chlorine feed rate, lb / day) = (flowrate, MGD) X (dose, mg / L) x (8.34). If this formula is correct, then what should the chlorine feed rate to be in pounds per day (lb / day) if the desired dose is 2 mg / L. (c) Prove by calculations that the constant 8.34 in the formula next to the chlorine feed point is correct. Let 1 US-gallon = 3.78541 L and 1 mg = 0.0000022046 pound.
How to calculate 40% of level in cylindrical vessel?
why rotameter has variable area?? is it necessary??
Question 60 – During the landing process of an airplane, the velocity is constant at v. (a) If the displacement of the plane is x at time t, find the differential equation that relates t, x and v. (b) The plane has 2 parts of wheels – the front and the back, separated by a distance L. The front part of the wheel touches the land first, that allows the straight body of the plane to form an angle T with the horizontal land. If the vertical distance between the back part of the wheel and the horizontal land is y, find the equation of y as a function of L and T. (c) Find the differential equation that relates dy as a function of dt, v and sin T. (d) Find the differential equation that consist of dy as a function of y, L, v and dt. (e) Find the equation of y as a function of v, L, t and C where C is a constant. (f) When t = 0, prove that y = exp C as the initial value of y.
In differential centrifugation of cells with diameter D in centimeter, the square of D is given by D x D = [18n ln (RF / RI) ] / [ (RP – RFF) Wt ] where n is the fluid viscosity (poise), RF is the final radius of rotation (cm), RI is the initial radius of rotation (cm), RP is cell density (g/ml), RFF is the fluid density (g/ml), W the square for the rotational velocity in (radians / s) (radians / s), t is the time required to sediment from RI to RF (s). Derive an equation for W as a function for D, n, RF, RI, RP, RFF and t, with the stated units above, in radian
Water flows through a pipe with circular cross sectional area at the rate of V / t = 80 L / s where V is the volume and t is time. Let Av = 80 L / s where A is cross sectional area and v is velocity of fluid. For point 1, the radius of the pipe is 16 cm. For point 2, the radius of the pipe is 8 cm. Find (a) the velocity at point 1; (b) the velocity at point 2; (c) the pressure at point 2 by using Bernoulli’s equation where P Rgy 0.5 RV = constant. P is the pressure, R = density of fluid, V = square of fluid’s velocity, g = gravitational constant of 9.81 N / kg and y = 2 m = difference of height at 2 points. The pressure of point 1 is 180 kPa.
I am a Diploma Chemical Engineer by Nirma Uni; and BEng (Hons) Energy & Environmental Engineer by Napier Uni; Edinburg, UK. HPCL chemical engineering test will held on 14th July,09. So, Please send me some previous chemical engineering papers Objective types Or material to give the test.
Part time jobs for engineer students working or studying
-
Civil Engineering (5085) - Mechanical Engineering (4451)
- Electrical Engineering (16632)
- Electronics Communications (3918)
- Chemical Engineering (1095)
- Aeronautical Engineering (239)
- Bio Engineering (96)
- Metallurgy (361)
- Industrial Engineering (259)
- Instrumentation (3014)
- Automobile Engineering (332)
- Mechatronics Engineering (97)
- Marine Engineering (124)
- Power Plant Engineering (172)
- Textile Engineering (575)
- Production Engineering (25)
- Satellite Systems Engineering (106)
- Engineering AllOther (1379)
