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Papers by Ma Norma Sevilla
Polymer Bulletin, 1996
The biosynthesis of poly (β-hydroxybutyrate) (PHB) byBacillus circulans was carried out through c... more The biosynthesis of poly (β-hydroxybutyrate) (PHB) byBacillus circulans was carried out through cultivation in nutrient broth in a single step. \(\overline {\text{M}} {\text{v}}\) of polymer fractions soluble in chloroform were close to 2 x 105. IR,1H and13C NMR spectra of the isolated PHB were in agreement with the assumed structure of this poly-β-hydroxyester. NMR spectroscopy pointed out a high percentage of isotactic polymer, while differential scanning calorimetry showed that the PHB was crystalline.
We investigate the relationship between a student's affect and how he or she chooses to use a sim... more We investigate the relationship between a student's affect and how he or she chooses to use a simulation problem-solving environment, using quantitative field observations. Within the environment studied, many students were observed gaming the system (cf. , while few students engaged in off-task behavior. We analyze which affective states co-occur with gaming the system, and which affective states precede gaming behavior. Boredom and confusion appear both to precede gaming behavior and to cooccur with gaming behavior; delight and flow are negatively associated with gaming behavior.
Polymer Bulletin, 1996
The biosynthesis of poly (β-hydroxybutyrate) (PHB) byBacillus circulans was carried out through c... more The biosynthesis of poly (β-hydroxybutyrate) (PHB) byBacillus circulans was carried out through cultivation in nutrient broth in a single step. \(\overline {\text{M}} {\text{v}}\) of polymer fractions soluble in chloroform were close to 2 x 105. IR,1H and13C NMR spectra of the isolated PHB were in agreement with the assumed structure of this poly-β-hydroxyester. NMR spectroscopy pointed out a high percentage of isotactic polymer, while differential scanning calorimetry showed that the PHB was crystalline.
We investigate the relationship between a student's affect and how he or she chooses to use a sim... more We investigate the relationship between a student's affect and how he or she chooses to use a simulation problem-solving environment, using quantitative field observations. Within the environment studied, many students were observed gaming the system (cf. , while few students engaged in off-task behavior. We analyze which affective states co-occur with gaming the system, and which affective states precede gaming behavior. Boredom and confusion appear both to precede gaming behavior and to cooccur with gaming behavior; delight and flow are negatively associated with gaming behavior.