Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Proceed order?

Export
Filter
  • Articles  (3)
  • lower critical solution temperature  (2)
  • chymotrypsin
  • Wiley-Blackwell  (3)
  • 1
    ISSN: 0887-6266
    Keywords: equation of state ; phase equilibria ; polymer solution ; lower critical solution temperature ; theta temperature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The perturbed hard-sphere-chain (PHSC) equation of state is used to calculate liquid-liquid equilibria of binary nonpolar solvent/homopolymer systems exhibiting both an upper critical solution temperature (UCST) and a lower critical solution temperature (LCST). Systems studied include polyisobutylene, polyethylene, and polystyrene solutions. Equation-of-state parameters of homopolymers are obtained by regressing the pressure-volume-temperature data of polymer melts. In polymer solutions, however, theory overestimates the equation-of-state effect which causes the LCST at elevated temperature. To correct the overestimated equation-of-state effect, an empirical adjustable parameter is introduced into the perturbation term of the PHSC equation of state. An entropy parameter is also introduced into the Helmholtz energy of the mixture to correlate quantitatively the dependence of critical temperatures on polymer molecular weight. For systems exhibiting a LCST, two adjustable parameters are required to obtain quantitative agreement of theoretical critical temperatures with experiment as a function of polymer molecular weight. For systems exhibiting both an UCST and a LCST, three adjustable parameters may be necessary. The need for so many empirical binary parameters is probably due to the oversimplified perturbation term which is based on the mean-field assumption. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0006-3592
    Keywords: reverse micelle ; solubilization ; light scattering ; chymotrypsin ; LADH ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Solubilization properties of α-chymotrypsin and alcohol dehydrogenase (LADH) in reverse micelles are reported for three different solubilization techniques. The solubilization properties for these two proteins depend on the method used for protein addition. The addition of a dry protein powder to a reverse-micelle-containing organic phase does not appreciably solubilize the protein until the diameter of the reverse micelle is similar to that of the protein. However, when an aqueous protein solution is injected an organic phase, protein solubilization is not strongly dependent on micelle size. For chymotrypsin, multiple protein occupancy occurs at large micelle size, with as many as 11 chymotrypsin molecules solubilized in one reverse micelle. The solubilization of chymotrypsin using a phase-transter technique with a positively charged surfactant follows the expected traned based on protein-surfactant electrostatic interactions. When a negatively charged sufactants is used for phase transfer, at low pH the solubilization data do not fit this electrostatic interaction mechanism. In this case, proteinsurfactant aggregation may be occurring at the aqueousorganic interface.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0887-6266
    Keywords: equation of state ; phase equilibria ; copolymer solution ; lower critical solution temperature ; theta temperature ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The perturbed hard-sphere-chain (PHSC) equation of state for copolymer systems is used to calculate liquid-liquid equilibria for binary solvent/copolymer systems that exhibit simultaneously an upper critical solution temperature (UCST) and a lower critical solution temperature. The PHSC equation of state for copolymer solutions uses those binary parameters that represent liquid-liquid equilibria for the two parent homopolymer solutions. An additional intersegmental parameter is also required to define the interaction energy between a pair of chemically dissimilar segments comprising the copolymer molecule. Theory is compared with experiment for binary copolymer solutions containing poly(styrene-co-α-methylstyrene) random copolymers. Using the same ΚBC, the intersegmental parameter between styrene and α-methylstyrene segments, theory and experiment show fair agreement for the copolymer-composition dependence of theta temperatures associated with UCST in cyclohexane, methyl cyclohexane, and decalin. A comparison is also made between ΚBC obtained from the copolymer-solution data and that obtained from the coexistence curve of homopolymer blends containing polystyrene and poly(α-methylstyrene). Data for copolymer solutions require a ΚBC that represents interactions more unfavorable than those in homopolymer blends. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...