TLS Online TPP Program

#Question id: 341


 Which force can stabilize a DNA double-helix?

#Section 2: General Biology
  1. Hydrophobic bases are found in the interior of the helix where each base-pair is stabilized by the same number of hydrogen bonds.

  2. Hydrophilic sugar-phosphate groups are found on the exterior of the helix where they can interact with water.

  3. Non-covalent N-glycosidic bonds can form between nitrogenous bases in opposite strands in the helix.

  4. Covalent base-stacking interactions can occur between adjacent bases within the same strand in the helix.

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TLS Online TPP Program

#Question id: 14226

#Section 5: Bioprocess Engineering and Process Biotechnology

A fermenter is maintained at 35⁰C by water circulating at a rate of 0.5 kg s^-1 in a cooling coil inside the vessel. The inlet and outlet temperatures of the water are 8⁰C and 15⁰C respectively. The length of the cooling coil is increased by 50%. In order to maintain the same fermentation temperature, the rate of heat removal must be kept the same. Determine the new cooling-water flow rate and outlet temperature by carrying out the following calculations. The heat capacity of the cooling water can be taken as 4.18 kJ kg^- 1 o C^- 1. Determine the mean temperature difference with the original coil.

TLS Online TPP Program

#Question id: 14227

#Section 5: Bioprocess Engineering and Process Biotechnology

A fermenter is maintained at 35⁰C by water circulating at a rate of 0.5 kg s^-1 in a cooling coil inside the vessel. The inlet and outlet temperatures of the water are 8⁰C and 15⁰C respectively. The length of the cooling coil is increased by 50%. In order to maintain the same fermentation temperature, the rate of heat removal must be kept the same. Determine the new cooling-water flow rate and outlet temperature by carrying out the following calculations. The heat capacity of the cooling water can be taken as 4.18 kJ kg^- 1 o C^- 1. Evaluate UA for the original coil. ________________

TLS Online TPP Program

#Question id: 14228

#Section 5: Bioprocess Engineering and Process Biotechnology

A fermenter is maintained at 35⁰C by water circulating at a rate of 0.5 kg s^-1 in a cooling coil inside the vessel. The inlet and outlet temperatures of the water are 8⁰C and 15⁰C respectively. The length of the cooling coil is increased by 50%. In order to maintain the same fermentation temperature, the rate of heat removal must be kept the same. Determine the new cooling-water flow rate and outlet temperature by carrying out the following calculations. The heat capacity of the cooling water can be taken as 4.18 kJ kg^- 1 o C^- 1. If the length of the coil is increased by 50⁰C the area available for heat transfer, A ', also increases by 50% so that A' = 1.5 A. The value of the overall heat-transfer coefficient is not expected to change very much. For the new coil, what is the value of UA’  ______________

TLS Online TPP Program

#Question id: 14229

#Section 5: Bioprocess Engineering and Process Biotechnology

A fermenter is maintained at 35⁰C by water circulating at a rate of 0.5 kg s^-1 in a cooling coil inside the vessel. The inlet and outlet temperatures of the water are 8⁰C and 15⁰C respectively. The length of the cooling coil is increased by 50%. In order to maintain the same fermentation temperature, the rate of heat removal must be kept the same. Determine the new cooling-water flow rate and outlet temperature by carrying out the following calculations. The heat capacity of the cooling water can be taken as 4.18 kJ kg^- 1 o C^- 1. By how much are the cooling-water requirements reduced after the new coil is installed?_____________

TLS Online TPP Program

#Question id: 14230

#Section 5: Bioprocess Engineering and Process Biotechnology

In current service, 20 kg s^-1 cooling water at 12⁰C must be circulated through a coil inside a fermenter to maintain the temperature at 37⁰C The coil is 150 m long with pipe diameter 12 cm; the exit water temperature is 28⁰C After the inner and outer surfaces of the coil are cleaned it is found that only 13 kg s^-1 cooling water is required to control the fermentation temperature. Calculate the overall heat-transfer coefficient before cleaning. _____________

TLS Online TPP Program

#Question id: 14231

#Section 5: Bioprocess Engineering and Process Biotechnology

In current service, 20 kg s^-1 cooling water at 12⁰C must be circulated through a coil inside a fermenter to maintain the temperature at 37⁰C The coil is 150 m long with pipe diameter 12 cm; the exit water temperature is 28⁰C After the inner and outer surfaces of the coil are cleaned it is found that only 13 kg s^-1 cooling water is required to control the fermentation temperature. Calculate the overall heat-transfer coefficient before cleaning. What fraction of the total resistance to heat transfer before cleaning was due to fouling deposits?____________