Papers by Keyword: Molecular Weight Distribution

Abstract: A very attractive and accepted approach to the modeling problem is building a hybrid model, where certain amounts of both phenomenological and empirical information are used. In this paper the mechanistic model is created by using the mathematical equations which are represented in the Matlab^TM Simulink environment so as to achieve a control over the bio-polymerization process. This mechanistic model was connected to a Feedforward Neural Network (FANN) model to complete the hybrid model of the process to predict the molecular weight distribution. The hybrid model in the Simulink environment was validated by comparing the results of the hybrid model with that of the experimental results carried out in a bioreactor.

Abstract: The results showed that DOC, UV₂₅₄ and SUVA all presented a characteristic that organics was mainly concentrated on molecular weight <1kDa.Except organics with molecular weight <1kDa, the molecular weight of organics in Influent and effluent of Hydrolytic Acidification respectively distributed in the range of <1kDa, 30~100kDa and 1~3kDa, 10~30kDa. Organics in effluent of Anaerobic, Aerobic, Secondary sedimentation tank and Contact oxidation occupied proportions in all ranges of molecular weight distribution but relatively lower.

Abstract: The main objective of this study was to investigate foulants in chemical cleaning solutions of membrane (CCSM). Sodium hydroxide (NaOH), sodium hypochlorite (NaOCl), hydrochloric acid (HCl) were used as chemical agents respectively. Hydrophobicity, molecular weight distribution and metal ions of foulants in CCSM were analyzed as the major characters for membrane fouling. Results reveal that alkali cleaning can remove both hydrophobic and hydrophilic fractions of natural organic matters (NOM), and acid cleaning mainly removes hydrophilic organic matters. Medium molecular weight of very hydrophobic acids (1-10 kDa) and different molecular weight of neutral hydrophilic acids (100-1000 Da & >300kDa) in NOM can lead to membrane irreversible fouling. Acid cleaning is relatively effective for the reduction of inorganic foulants. The main metal ions in acid cleaning solutions are K ,Ca, Al and Mn, which are responsible for membrane inorganic fouling.

Abstract: Soybean protein Alcalase hydrolysate was further hydrolyzed by adopting Flavourzyme. From this further hydrolysis reaction, bitter of soybean polypeptide mixture was reduced distinctly. The optimal hydrolysis conditions of Flavourzyme was determined as that pH was 7.0 at temperature 50°C and E/S(ratio of enzyme and substrate) was 20LAPU/g. Bitter taste value was reduced to 2 after Flavourzyme hydrolysis reaction for 2 hours in optimal hydrolysis conditions. The change of molecular weight distribution range from Alcalase hydrolysate to Flavourzyme hydrolysate was not obvious. DH (Degree of hydrolysis) of soybean protein hydrolysate was increased to 24.2% which was improved 3.5% than Alcalase hydrolysate. Protein recovery proportion was increased to 73.2% which was improved 0.8% than Alcalase hydrolysate.

Abstract: The effects of initiator, modifier, electrolyte, and emulsifier on emulsion polymerization of styrene butadiene rubber were investigated. The results showed that the conversion could reach up to 70% within 12 hour with the same properties as conversion 62% without changing the kinds and specification by using the adjusted recipe: the amount of initiator was 10%, the mass ratio of initial amount to addition amount of molecular weight regulator was 100/20, addition time was at polymerization beginning 2 hour, the initial amount of electrolyte was 110%-115%, the total amount of emulsifier was 110%, the addition amount of emulsifier was 10% and adding time was at polymerization beginning 2 hour. the raw and vulcanizate properties of rubber crumb high monomer conversion of 70% by adjusting recipe were satisfied to meet the requirements of the superior product standard of styrene butadiene rubber.