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RISS 인기검색어
- 검색키워드
- 저자 : Allan S. Myerson (검색결과 4 건)
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Solid forms of pharmaceuticals: Polymorphs, salts and cocrystals
Bipul Sarma,Allan S. Myerson,Jie Chen,Huai-Ying Hsi 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2
Control and selection of the properties of active pharmaceutical ingredients is a crucial part of the drug development process. One major part of this process is the selection of an appropriate solid form. This review will discuss three major types of crystalline solids, polymorphs, salts and cocrystals and processes used to develop and find these forms.
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Diffusivity of Protein in Aqueous Solutions
Kim, Yeong Chul,Myerson, Allan S 한국화학공학회 1996 NICE Vol.14 No.4
The diffusion coefficient of lysozyme, a globular protein, was measured at various conditions as functions of lysozyme concentration, salt amcentration, and solution age in concentrated, saturated, and supersaturated solutions, employing Gouy intetferometry. Distilled water, 0.05 M potassium phosphate buffer, and 0.1 M sodium acetate buffer solutions with 0, 2, 4, and 5 wt% NaCl were used as solvents. The pH of lysozyme solutions in distilled water was 4.75 due to the self-buffering capacity, of lysozyme. The pH's of the lysozyme solutions in the potassium phosphate and sodium acetate buffers were adjusted to 6.8 and 4.0, respectively. The experimental temperature was 25. In a salt-free system, the concentration dependent diffusion of lysozyme showed typical electrolyte diffusion behavior, while a salt-poly electrolyte system exhibited the behavior of a non-electrolyte. Diffusion results in the supersaturated region showed a little effect of concentration or solution age at a fixed NaCl concentration. A rapid decline in diffusion coefficient with increasing NaCl concentration in the supersaturated region, however, was observed.
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DIFFUSIVITY OF PROTEIN IN AQUEOUS SOLUTIONS
Kim, Yeong Chul,Myerson, Allan S 한국화학공학회 1996 Korean Journal of Chemical Engineering Vol.13 No.3
The diffusion coefficient of lysozyme, a globular protein, was measured at various conditions as functions of lysozyme concentration, salt concentration, and solution 'age' in concentrated, saturated, and supersaturated solutions, employing Gouy interferometry. Distilled water, 0.05 M potassium phosphate buffer, and 0.1 M sodium acetate buffer solutions with 0, 2, 4, and 5 wt% NaCl were used as solvents. The pH of lysozyme solutions in distilled water was 4.75 due to the self-buffering capacity of lysozyme. The pH's of the lysozyme solutions in the potassium phosphate and sodium acetate buffers were adjusted to 6.8 and 4.0, respectively. The experimental temperature was 25℃. In a salt-free system, the concentration dependent diffusion of lysozyme showed typical electrolyte diffusion behavior, while a salt-polyelectrolyte system exhibited the behavior of a non-electrolyte. Diffusion results in the supersaturated region showed a little effect of concentration or solution 'age' at a fixed NaCl concentration. A rapid decline in diffusion coefficient with increasing NaCl concentration in the supersaturated region, however, was observed.
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Phase Transformation of Sulfamerazine Using a Taylor Vortex
Lee, Sun,Choi, Areum,Kim, Woo-Sik,Myerson, Allan S. American Chemical Society 2011 Crystal Growth & Design Vol.11 No.11
<P>A Couette–Taylor (CT) crystallizer was used to demonstrate the unique fluid dynamic properties of a Taylor vortex for the phase transformation of sulfamerazine (SMZ). With a conventional Rushton mixing tank (MT) crystallizer, the phase transformation from a metastable crystalline phase to the stable crystalline phase took more than 60 h with acetonitrile (ACN) as the solvent and an agitation rate of 3000 rpm. Using a CT crystallizer, this phase transformation occurred within 3–7 h with rotation speeds in the CT crystallizer of 300–1000 rpm. Increasing the rotation speed of the CT crystallizer also significantly enhanced the phase transformation, whereas adding water to the solvent increased the solubility difference between the two polymorphs and accelerated the phase transformation in both crystallizers. The phase transformation in the CT crystallizer was always many times faster than that in the MT crystallizer. Nucleation and mass-transfer models were used to describe the nucleation induction time of the stable crystal form and the transformation of metastable crystals into stable crystals. The influence of the fluid motions of the periodic Taylor vortex and random eddy in the CT and MT crystallizer, respectively, on the induction time was correlated by the nucleation enhancement factor, which was expressed as function of energy dissipation. The resulting induction and transformation times correlated well with the experimental data in terms of the energy dissipation and solubility difference across the whole range of phase transformation conditions, including rotation speeds, water fractions, and temperatures.</P><P>Using a conventional Rushton mixing tank crystallizer, the phase transformation from a metastable crystalline phase to the stable crystalline phase took more than 60 h with acetonitrile as the solvent and an agitation rate of 3000 rpm. Using a Couette−Taylor crystallizer, this phase transformation occurred within 3−7 h at rotation speeds of 300−1000 rpm.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cgdefu/2011/cgdefu.2011.11.issue-11/cg200925v/production/images/medium/cg-2011-00925v_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cg200925v'>ACS Electronic Supporting Info</A></P>
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