Biomedical subjects

Jinshan Li

Publications and source records attributed to Jinshan Li.

3 recordsLinked to original sources

PubMed2006

Medium optimization by combination of response surface methodology and desirability function: an application in glutamine production.

An optimization strategy based on desirability function approach (DFA) together with response surface methodology (RSM) has been used to optimize production medium in L-glutamine fermentation. Fermentation problems often force to reach a compromise between different experimental variables in order to achieve the most suitable strategy applying in industrial production. The importance of the use of multi-objective optimization methods lies in the ability to cope with this kind of problems. A sequential RSM with different combinations of glucose and (NH(4))(2)SO(4) was performed to attain the optimal medium (OM-1) in glutamine production. Based on the result of RSM and the evaluation of production cost, a more economical optimal medium (OM-2) was obtained with the aid of DFA. In DFA study, glutamate, the main by-product in glutamine fermentation as another response was considered. Compared with OM-1 in validated experiment, similar amounts of glutamine were obtained in OM-2 while the concentration of glutamate and the production cost decreased by 53.6 and 7.1%, respectively.

Biotechnology↗

PubMed2004

Study on reactions of 2-(dinitromethylene)-4,5-imidazolidinedione.

Some new reactions of 2-(dinitromethylene)-4,5-imidazolidinedione (1) with water, alcohols, carboxylic acids, and alkalis were discovered. By reaction of 1 with carboxylic acids, large particle size 1,1-diamino-2,2-dinitroethylene (2) was prepared. By reaction of 1 with methanol, the methanol adduct (4) was synthesized and characterized. By reaction of 1 with water, the synthetic pathway of 2-methylimidazole to 2 could be achieved in a continuous process. By reaction of 1 with KOH, 2 and potassium dinitromethane (6) could be formed at different temperature, respectively. Compounds 1 and 4 decomposed into parabanic acid (5), losing nitrogen oxides and carbon oxides. Some explosive properties of 1 were studied. The mechanisms of synthesis of 1, 2, and 5 are discussed.

Journal Article↗

PubMed2003

An ab initio study of intermolecular interactions of nitromethane dimer and nitromethane trimer.

Different geometries of nitromethane dimer and nitromethane trimer have been fully optimized employing the density functional theory B3LYP method and the 6-31++G** basis set. Three-body interaction energy has been obtained with the ab initio supermolecular approach at the levels of MP2/6-31++G**//B3LYP/6-31++G** and MP2/aug-cc-pVDZ//B3LYP/6-31++G**. The internal rotation of methyl group induced by intermolecular interaction has been observed theoretically. For the optimized structures of nitromethane dimer, the strength of C--H...O--N H-bond ranges from -9.0 to -12.4 kJ mol(-1) at the MP2/aug-cc-pVDZ//B3LYP/6-31++G** level, and the B3LYP method underestimates the interaction strength compared with the MP2 method, while MP2/6-31++G**//B3LYP/6-31++G** calculated DeltaE(C) is within 2.5 kJ mol(-1) of the corresponding value at the MP4(SDTQ)/6-31G**//B3LYP/6-31++G** level. The analytic atom-atom intermolecular potential has been successfully regressed by using the MP2/6-31++G**//B3LYP/6-31++G** calculated interaction energies of nitromethane dimer. For the optimized structures of nitromethane trimer the three-body interaction energies occupy small percentage of corresponding total binding energies, but become important for the compressed nitromethane explosive. In addition, it has been discovered that the three-body interaction energy in the cyclic nitromethane trimer is more and more negative as intermolecular distances decrease from 2.2 to 1.7 A.

Journal Article↗