Sohrab Rohani - Academia.edu (original) (raw)
Papers by Sohrab Rohani
Polymorphism in pharmaceutical solids is a major issue that has medical, financial and legal impl... more Polymorphism in pharmaceutical solids is a major issue that has medical, financial and legal implications. There are many thermodynamics and kinetics factors which affect the polymorph selectivity during the crystallization process such as nucleation temperature, supersaturation and type of solvent. Among these parameters, type of solvent is a major kinetic factor that has drawn the attention of researchers. Literature is ripe with research showing the effect of solvent on the polymorph selectivity, mainly using the polar and non-polar terminology, but seldom the researchers have explained the effect of solvent at molecular level. This work looks into the effect of solvent and the corresponding intermolecular interactions on the polymorphic selectivity. Two case studies on the effect of solvent will be discussed for polymorphic systems of stearic acid (used for tablet coating) and ranitidine hydrochloride (H2-receptor antagonist drug). Introduction Polymorphism is the phenomenon tha...
CrystEngComm
A case study portraying how a labile tri-methanol solvate of dasatinib leads to polymorph transfo... more A case study portraying how a labile tri-methanol solvate of dasatinib leads to polymorph transformation and particle size reduction.
The Canadian Journal of Chemical Engineering
Molecules
In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter... more In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter: PEA), which is soluble in water, (R)-(+)-benzyl-1-phenylethylamine ((R)-(+)-BPA) was used to resolve 4-chloromandelic acid (4-ClMA) in this study. The optimal resolution conditions were determined: absolute ethanol as a solvent, the molar ratio of 4-ClMA to (R)-(+)-BPA as 1:1, the filtration temperature as 15 °C, and the amount of solvent as 1.6 mL/1 mmol 4-ClMA. Thermophysical properties, such as melting point, heat of fusion, and solubility, exhibited significant differences between the less and more soluble salts. The single crystals for the pair of diastereomeric salts were cultivated and their crystal structures were examined thoroughly. In addition to commonly observed interactions like hydrogen bonding and CH/π interactions. The chlorine…chlorine interaction was observed in the less soluble salt presenting as Cl…Cl between adjacent hydrogen network columns, while the Cl/π intera...
Nanomaterials (Basel, Switzerland), Jan 28, 2018
In this investigation, a new, facile, low cost and environmental-friendly method was introduced t... more In this investigation, a new, facile, low cost and environmental-friendly method was introduced to fabricate N- and C-modified TiO₂ nanotube arrays by immersing the as-anodized TiO₂ nanotube arrays (TNTAs) in a urea aqueous solution with mechanical agitation for a short time and keeping the TNTAs immersed in the solution for 6 h at room temperature. Then, the TNTAs were annealed at different temperatures. The produced N-, C-modified TNTAs were characterized using FESEM, EDX, XRD, XPS, UV-Vis diffuse reflectance spectra. Modified optical properties with narrow band gap energy, E, of 2.65 eV was obtained after annealing the modified TNTAs at 550 °C. Modified TNTAs showed enhanced photoelectochemical performance. Photoconversion efficiency (PCE) was increased from 4.35% for pristine (unmodified) TNTAs to 5.18% for modified TNTAs, an increase of 19%. Effect of nanotubes length of modified TNTAs on photoelectrochemical performance was also studied. Photocurrent density and PCE were i...
Organic Process Research & Development
ABSTRACT
African Journal of Pharmacy and Pharmacology
Nanomaterials (Basel, Switzerland), Jan 25, 2017
The development of a portable oxygen concentrator is of prime significance for patients with resp... more The development of a portable oxygen concentrator is of prime significance for patients with respiratory problems. This paper presents a portable concentrator prototype design using the pressure/vacuum swing adsorption (PVSA) cycle with a deep evacuation step (-0.82 barg) instead of desorption with purge flow to simplify the oxygen production process. The output of the oxygen concentrator is a ~90 vol % enriched oxygen stream in a continuous adsorption and desorption cycle (cycle time ~90 s). The size of the adsorption column is 3 cm in diameter and 20 cm in length. A Li⁺ exchanged 13X nanosize zeolite is used as the adsorbent to selectively adsorb nitrogen from air. A dynamic model of the pressure and vacuum swing adsorption units was developed to study the pressurization and depressurization process inside the microporous area of nanosized zeolites. The describing equations were solved using COMSOL Multiphysics Chemical Engineering module. The output flow rate and oxygen concentra...
Organic Process Research & Development, 2009
... Doaa M. Ragab and Sohrab Rohani*. Department of Chemical and Biochemical Engineering, The Uni... more ... Doaa M. Ragab and Sohrab Rohani*. Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario, Canada N6A 5B9. Org. Process Res. Dev. , 2009, 13 (6), pp 12151223. DOI: 10.1021 ...
Chem Eng Commun, 2004
ABSTRACT
Chemical Engineering Science, 1988
Industrial Engineering Chemistry Process Design and Development, 1986
Journal of Crystal Growth, May 1, 2004
2007 European Control Conference, Jul 2, 2007
Most chemical processes are operated under continuously changing conditions and thus the optimal ... more Most chemical processes are operated under continuously changing conditions and thus the optimal operating conditions change with time. On-line optimization techniques of various types which are used to track these kinds of moving optimum, have sparked significant interest in recent years. A multi-variable, adaptive, fuzzy logic based approach is presented here for real-time optimization of nonlinear dynamic chemical processes. The approach is model-free and utilizes only the online plant measurements and a set of properly formulated fuzzy rules to keep the process always at optimum conditions despite changes in environmental conditions. Both simulation and experimental studies point to the efficiency of the approach. The algorithm yields reasonably fast convergence and a robust performance against noisy and inaccurate signals.
Crystal Research and Technology, May 1, 2012
Polymorphism in pharmaceutical solids is a major issue that has medical, financial and legal impl... more Polymorphism in pharmaceutical solids is a major issue that has medical, financial and legal implications. There are many thermodynamics and kinetics factors which affect the polymorph selectivity during the crystallization process such as nucleation temperature, supersaturation and type of solvent. Among these parameters, type of solvent is a major kinetic factor that has drawn the attention of researchers. Literature is ripe with research showing the effect of solvent on the polymorph selectivity, mainly using the polar and non-polar terminology, but seldom the researchers have explained the effect of solvent at molecular level. This work looks into the effect of solvent and the corresponding intermolecular interactions on the polymorphic selectivity. Two case studies on the effect of solvent will be discussed for polymorphic systems of stearic acid (used for tablet coating) and ranitidine hydrochloride (H2-receptor antagonist drug). Introduction Polymorphism is the phenomenon tha...
CrystEngComm
A case study portraying how a labile tri-methanol solvate of dasatinib leads to polymorph transfo... more A case study portraying how a labile tri-methanol solvate of dasatinib leads to polymorph transformation and particle size reduction.
The Canadian Journal of Chemical Engineering
Molecules
In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter... more In order to avoid the disadvantage of commonly used resolving agent 1-phenylethylamine (hereafter: PEA), which is soluble in water, (R)-(+)-benzyl-1-phenylethylamine ((R)-(+)-BPA) was used to resolve 4-chloromandelic acid (4-ClMA) in this study. The optimal resolution conditions were determined: absolute ethanol as a solvent, the molar ratio of 4-ClMA to (R)-(+)-BPA as 1:1, the filtration temperature as 15 °C, and the amount of solvent as 1.6 mL/1 mmol 4-ClMA. Thermophysical properties, such as melting point, heat of fusion, and solubility, exhibited significant differences between the less and more soluble salts. The single crystals for the pair of diastereomeric salts were cultivated and their crystal structures were examined thoroughly. In addition to commonly observed interactions like hydrogen bonding and CH/π interactions. The chlorine…chlorine interaction was observed in the less soluble salt presenting as Cl…Cl between adjacent hydrogen network columns, while the Cl/π intera...
Nanomaterials (Basel, Switzerland), Jan 28, 2018
In this investigation, a new, facile, low cost and environmental-friendly method was introduced t... more In this investigation, a new, facile, low cost and environmental-friendly method was introduced to fabricate N- and C-modified TiO₂ nanotube arrays by immersing the as-anodized TiO₂ nanotube arrays (TNTAs) in a urea aqueous solution with mechanical agitation for a short time and keeping the TNTAs immersed in the solution for 6 h at room temperature. Then, the TNTAs were annealed at different temperatures. The produced N-, C-modified TNTAs were characterized using FESEM, EDX, XRD, XPS, UV-Vis diffuse reflectance spectra. Modified optical properties with narrow band gap energy, E, of 2.65 eV was obtained after annealing the modified TNTAs at 550 °C. Modified TNTAs showed enhanced photoelectochemical performance. Photoconversion efficiency (PCE) was increased from 4.35% for pristine (unmodified) TNTAs to 5.18% for modified TNTAs, an increase of 19%. Effect of nanotubes length of modified TNTAs on photoelectrochemical performance was also studied. Photocurrent density and PCE were i...
Organic Process Research & Development
ABSTRACT
African Journal of Pharmacy and Pharmacology
Nanomaterials (Basel, Switzerland), Jan 25, 2017
The development of a portable oxygen concentrator is of prime significance for patients with resp... more The development of a portable oxygen concentrator is of prime significance for patients with respiratory problems. This paper presents a portable concentrator prototype design using the pressure/vacuum swing adsorption (PVSA) cycle with a deep evacuation step (-0.82 barg) instead of desorption with purge flow to simplify the oxygen production process. The output of the oxygen concentrator is a ~90 vol % enriched oxygen stream in a continuous adsorption and desorption cycle (cycle time ~90 s). The size of the adsorption column is 3 cm in diameter and 20 cm in length. A Li⁺ exchanged 13X nanosize zeolite is used as the adsorbent to selectively adsorb nitrogen from air. A dynamic model of the pressure and vacuum swing adsorption units was developed to study the pressurization and depressurization process inside the microporous area of nanosized zeolites. The describing equations were solved using COMSOL Multiphysics Chemical Engineering module. The output flow rate and oxygen concentra...
Organic Process Research & Development, 2009
... Doaa M. Ragab and Sohrab Rohani*. Department of Chemical and Biochemical Engineering, The Uni... more ... Doaa M. Ragab and Sohrab Rohani*. Department of Chemical and Biochemical Engineering, The University of Western Ontario, London, Ontario, Canada N6A 5B9. Org. Process Res. Dev. , 2009, 13 (6), pp 12151223. DOI: 10.1021 ...
Chem Eng Commun, 2004
ABSTRACT
Chemical Engineering Science, 1988
Industrial Engineering Chemistry Process Design and Development, 1986
Journal of Crystal Growth, May 1, 2004
2007 European Control Conference, Jul 2, 2007
Most chemical processes are operated under continuously changing conditions and thus the optimal ... more Most chemical processes are operated under continuously changing conditions and thus the optimal operating conditions change with time. On-line optimization techniques of various types which are used to track these kinds of moving optimum, have sparked significant interest in recent years. A multi-variable, adaptive, fuzzy logic based approach is presented here for real-time optimization of nonlinear dynamic chemical processes. The approach is model-free and utilizes only the online plant measurements and a set of properly formulated fuzzy rules to keep the process always at optimum conditions despite changes in environmental conditions. Both simulation and experimental studies point to the efficiency of the approach. The algorithm yields reasonably fast convergence and a robust performance against noisy and inaccurate signals.
Crystal Research and Technology, May 1, 2012