1
|
Liquid-liquid chromatography in enantioseparations. J Chromatogr A 2020; 1626:461345. [DOI: 10.1016/j.chroma.2020.461345] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 06/12/2020] [Accepted: 06/12/2020] [Indexed: 12/20/2022]
|
2
|
Hydrodynamics studies of the behaviour of traditional and two-phase ionic liquid solvent systems in countercurrent chromatography (CCC). Chem Eng Sci 2018. [DOI: 10.1016/j.ces.2018.07.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
3
|
Quan KJ, Xi XJ, Huang XY, Duan WD, Pei D, Di DL. A simple gradient equilibrium method for better separation in countercurrent chromatography. J Sep Sci 2018; 41:3863-3870. [PMID: 30152913 DOI: 10.1002/jssc.201800533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 07/16/2018] [Accepted: 08/11/2018] [Indexed: 11/11/2022]
Abstract
The stationary phase retention is one of the most important parameters in countercurrent chromatography. In this work, a simple gradient equilibrium method was developed to further improve the stationary phase retention based on the optimized condition in the traditional equilibrium model. Meanwhile, this novel gradient equilibrium method was used to separate three flavone model compounds and compared with the conventional isocratic equilibrium method to evaluate the separation efficiency. The results show that better resolution or shorter separation time could be achieved with gradient equilibrium compared to isocratic equilibrium. So this novel equilibrium method has enormous potential for obtaining a better separation or saving the separating time in the preparative separation of target compounds.
Collapse
Affiliation(s)
- Kai-Jun Quan
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Chinese Academy of Sciences, Lanzhou Institute of Chemical Physics, Lanzhou, China.,University of the Chinese Academy of Sciences, Beijing, China
| | - Xing-Jun Xi
- Food and Agriculture Standardization Institute, China National Institute of Standardization, Beijing, China
| | - Xin-Yi Huang
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Chinese Academy of Sciences, Lanzhou Institute of Chemical Physics, Lanzhou, China
| | - Wen-Da Duan
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Chinese Academy of Sciences, Lanzhou Institute of Chemical Physics, Lanzhou, China.,University of the Chinese Academy of Sciences, Beijing, China
| | - Dong Pei
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Chinese Academy of Sciences, Lanzhou Institute of Chemical Physics, Lanzhou, China
| | - Duo-Long Di
- Key Laboratory of Chemistry of Northwestern Plant Resources and Key Laboratory for Natural Medicine of Gansu Province, Chinese Academy of Sciences, Lanzhou Institute of Chemical Physics, Lanzhou, China
| |
Collapse
|
4
|
Huang XY, Pei D, Liu JF, Di DL. A review on chiral separation by counter-current chromatography: Development, applications and future outlook. J Chromatogr A 2018; 1531:1-12. [DOI: 10.1016/j.chroma.2017.10.073] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 10/27/2017] [Accepted: 10/29/2017] [Indexed: 12/21/2022]
|
5
|
Kumar D, Pandey J, Raj V, Kumar P. A Review on the Modification of Polysaccharide Through Graft Copolymerization for Various Potential Applications. THE OPEN MEDICINAL CHEMISTRY JOURNAL 2017; 11:109-126. [PMID: 29151987 PMCID: PMC5676014 DOI: 10.2174/1874104501711010109] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/20/2017] [Accepted: 08/23/2017] [Indexed: 12/03/2022]
Abstract
INTRODUCTION Graft copolymerization is one of the most promising technique uses to modify the properties of naturally available polymers with a minimum loss in their native characteristics. METHODS AND MATERIALS Graft copolymerization is a very significant technique to add hybrid properties in backbone of polymers. The grafting generally initiated through the formation of free radical centers on the polymer backbone as well as monomer. RESULTS Grafted polysaccharides have various applications in different important scientific areas such as drug delivery, pharmaceutical field, plastic industry, waste water treatment, tannery effluent treatment, textile industry, agriculture area, etc. all of this fascinated us to summarize the major research articles over the last two decades outlining different methods of grafting, surface modification, graft copolymerization of synthetic and natural polymers. CONCLUSION Various redox initiator systems viz. Ceric ammonium nitrate, per sulfate, Irradiation, FAS-H2O2etc. is also explored for grafting of vinyl through conventional and non-conventional techniques.
Collapse
Affiliation(s)
- Deepak Kumar
- Department of Applied Chemistry, MJP Rohilkhand University, Bareilly – 243006(U.P.), India
- Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rae Bareli Road, Lucknow 226025, India
| | - Jyoti Pandey
- Department of Applied Chemistry, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rae Bareli Road, Lucknow 226025, India
| | - Vinit Raj
- Department of Pharmaceutical Sciences, Babasaheb Bhimrao Ambedkar University, Vidya Vihar, Rae Bareli Road, Lucknow 226025, India
| | - Pramendra Kumar
- Department of Applied Chemistry, MJP Rohilkhand University, Bareilly – 243006(U.P.), India
| |
Collapse
|
6
|
Ding J, Li S, Zhao Y, Guan YH, Deng L, Deng Q. Properties of hydrodynamic J-type countercurrent chromatography for protein separation using aqueous two-phase systems: With special reference to constructing conical columns. J Chromatogr A 2017; 1499:101-110. [DOI: 10.1016/j.chroma.2017.03.076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 03/19/2017] [Accepted: 03/24/2017] [Indexed: 10/19/2022]
|
7
|
Vázquez-Villegas P, Ouellet E, González C, Ruiz-Ruiz F, Rito-Palomares M, Haynes CA, Aguilar O. A microdevice assisted approach for the preparation, characterization and selection of continuous aqueous two-phase systems: from micro to bench-scale. LAB ON A CHIP 2016; 16:2662-2672. [PMID: 27302418 DOI: 10.1039/c6lc00333h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Aqueous two-phase systems (ATPS) have emerged as an alternative strategy for the recovery and purification of a wide variety of biological products. Typical process development requires a large screening of experimental conditions towards industrial adoption where continuous processes are preferred. In this work, it was proved that under certain flow conditions, ATPS could be formed continuously inside a microchannel, starting from stocks of phase components. Staggered herringbone chaotic micromixers included within the device sequentially and rapidly prepare two-phase systems across an entire range of useful phase compositions. Two-phase diagrams (binodal curves) were easily plotted using the cloud-point method for systems of different components and compared with previously reported curves for each system, proving that phase formation inside the device correlated with the previously reported diagrams. A proof of concept for sample partitioning in such a microdevice was performed with two different experimental models: BSA and red blood cells. Finally, the microdevice was employed to obtain information about the recovery and partition coefficient of invertase from a real complex mixture of proteins (yeast extract) to design a process for the recovery of the enzyme selecting a suitable system and composition to perform the process at bench-scale.
Collapse
Affiliation(s)
- Patricia Vázquez-Villegas
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
| | - Eric Ouellet
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
| | - Claudia González
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
| | - Federico Ruiz-Ruiz
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
| | - Marco Rito-Palomares
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
| | - Charles A Haynes
- Michael Smith Laboratories, University of British Columbia, Vancouver, BC, V6T 1Z4 Canada
| | - Oscar Aguilar
- Escuela de Ingeniería y Ciencias, Tecnologico de Monterrey, Ave. Eugenio Garza Sada 2501, Monterrey, N.L. 64849, Mexico.
| |
Collapse
|
8
|
Shinomiya K, Yoshida K, Tokura K, Tsukidate E, Yanagidaira K, Ito Y. Countercurrent chromatographic separation of proteins using an eccentric coiled column with synchronous and nonsynchronous type-J planetary motions. ANAL SCI 2016; 31:211-8. [PMID: 25765276 DOI: 10.2116/analsci.31.211] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Protein separation was performed using the high-speed countercurrent chromatograph (HSCCC) at both synchronous and nonsynchronous type-J planetary motions. The partition efficiency was evaluated with two different column configurations, eccentric coil and toroidal coil, on the separation of a set of stable protein samples including cytochrome C, myoglobin and lysozyme with a polymer phase system composed of 12.5% (w/w) polyethylene glycol 1000 and 12.5% (w/w) dibasic potassium phosphate. Better peak resolution was obtained by the eccentric coil than by the toroidal coil using either lower or upper phase as the mobile phase. The peak resolution was further improved using the eccentric coil by the nonsynchronous type-J planetary motion with the combination of 1066 rpm of column rotation and 1000 rpm of revolution.
Collapse
|
9
|
Scale-up protein separation on stainless steel wide bore toroidal columns in the type-J counter-current chromatography. J Chromatogr A 2015; 1424:102-10. [DOI: 10.1016/j.chroma.2015.03.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 02/27/2015] [Accepted: 03/02/2015] [Indexed: 11/22/2022]
|
10
|
Friesen JB, McAlpine JB, Chen SN, Pauli GF. Countercurrent Separation of Natural Products: An Update. JOURNAL OF NATURAL PRODUCTS 2015; 78:1765-96. [PMID: 26177360 PMCID: PMC4517501 DOI: 10.1021/np501065h] [Citation(s) in RCA: 198] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Indexed: 05/02/2023]
Abstract
This work assesses the current instrumentation, method development, and applications in countercurrent chromatography (CCC) and centrifugal partition chromatography (CPC), collectively referred to as countercurrent separation (CCS). The article provides a critical review of the CCS literature from 2007 since our last review (J. Nat. Prod. 2008, 71, 1489-1508), with a special emphasis on the applications of CCS in natural products research. The current state of CCS is reviewed in regard to three continuing topics (instrumentation, solvent system development, theory) and three new topics (optimization of parameters, workflow, bioactivity applications). The goals of this review are to deliver the necessary background with references for an up-to-date perspective of CCS, to point out its potential for the natural product scientist, and thereby to induce new applications in natural product chemistry, metabolome, and drug discovery research involving organisms from terrestrial and marine sources.
Collapse
Affiliation(s)
- J. Brent Friesen
- Department
of Medicinal Chemistry and Pharmacognosy and Institute for Tuberculosis Research,
College of Pharmacy, University of Illinois
at Chicago, Chicago, Illinois 60612, United
States
- Physical
Sciences Department, Rosary College of Arts and Sciences, Dominican University, River Forest, Illinois 60305, United States
| | - James B. McAlpine
- Department
of Medicinal Chemistry and Pharmacognosy and Institute for Tuberculosis Research,
College of Pharmacy, University of Illinois
at Chicago, Chicago, Illinois 60612, United
States
| | - Shao-Nong Chen
- Department
of Medicinal Chemistry and Pharmacognosy and Institute for Tuberculosis Research,
College of Pharmacy, University of Illinois
at Chicago, Chicago, Illinois 60612, United
States
| | - Guido F. Pauli
- Department
of Medicinal Chemistry and Pharmacognosy and Institute for Tuberculosis Research,
College of Pharmacy, University of Illinois
at Chicago, Chicago, Illinois 60612, United
States
| |
Collapse
|
11
|
Kurnia KA, Freire MG, Coutinho JAP. Effect of Polyvalent Ions in the Formation of Ionic-Liquid-Based Aqueous Biphasic Systems. J Phys Chem B 2013; 118:297-308. [DOI: 10.1021/jp411933a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Kiki A. Kurnia
- Departamento de Química,
CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - Mara G. Freire
- Departamento de Química,
CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| | - João A. P. Coutinho
- Departamento de Química,
CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
| |
Collapse
|
12
|
|
13
|
Developments of instruments and methods related with high-speed countercurrent chromatography and their applications in research of natural medicines. OPEN CHEM 2012. [DOI: 10.2478/s11532-011-0141-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractHigh-speed countercurrent chromatography (HSCCC) is a liquid-liquid separation chromatographic technique which uses no solid supporting medium. During its rapid development in the last 30 years, great progress has been made in the instrumentation, the basic study and application of HSCCC. It has significant advantages over other instrumental separation techniques, in its high efficiency and continuous processing capability. In recent years, HSCCC has been widely used in research and development of natural medicines and functional foods, including preparative separation, fingerprint analysis and screening of bioactive constituents. A review of the technique is presented in this paper.
Collapse
|
14
|
Guan YH, van den Heuvel RNAM, Zhuang YP. Visualisation of J-type counter-current chromatography: a route to understand hydrodynamic phase distribution and retention. J Chromatogr A 2012; 1239:10-21. [PMID: 22513130 PMCID: PMC3405518 DOI: 10.1016/j.chroma.2012.03.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 03/11/2012] [Accepted: 03/13/2012] [Indexed: 11/15/2022]
Abstract
This paper has addressed decade sought-after questions on phase bilateral distribution and stationary phase retention in any J-type high-speed counter-current chromatographic (CCC) centrifuge. Using a 2-D spiral column operated on such a CCC device and an aqueous two-phase system, this work systematically observed the phase interaction during transitional period and at dynamic equilibration under stroboscopic illumination. The experimental results thus obtained were used to examine the effects of the liquid-solid friction force, tangential centrifugal force, and physical properties of the two-phase system on hydrodynamic phase behaviour. We identified that (a) density difference between lower and upper phases is the critical factor to cause unusual phase bilateral distribution in the 2-D spiral column and (b) interfacial tension (manifested primarily as phase settling time) of any two-phase system is the critical factor in explaining inability to retain stationary phase in 3-D helical column and, for certain flow modes, in the 2-D spiral column. This work thus has extended or modified the well-established rule-of-thumb for operating J-type CCC devices and our conclusions can accommodate virtually all the anomalies concerning both hydrophobic and hydrophilic phase systems. To this end, this work has not only documented valuable experimental evidences for directly observing phase behaviour in a CCC column, but also finally resolved fundamentally vital issues on bilateral phase distribution orientation and stationary phase retention in 2-D spiral and 3-D helical CCC columns. Revised recommendations to end users of this technology could thus be derived out of the essence of the present work presumably following further experimental validation and a consensus in the CCC R&D and manufacturing circle.
Collapse
Affiliation(s)
- Yue Hugh Guan
- State Key Laboratory of Bioreactor Engineering, & The College of Biotechnology, East China University of Science & Technology, Shanghai 200237, China.
| | | | | |
Collapse
|
15
|
Sutherland I, Hewitson P, de Folter J. Toroidal coil chromatography: the effect of scale-up and "g" field on stage efficiency. J Chromatogr A 2011; 1218:6144-7. [PMID: 21227439 PMCID: PMC3223526 DOI: 10.1016/j.chroma.2010.12.090] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Revised: 12/17/2010] [Accepted: 12/21/2010] [Indexed: 12/04/2022]
Abstract
Selected test results have been taken from various publications and resolution and stage efficiency measured using an established model. All experiments used the same sample and, where possible, the same sample loading. The results show that stage mixing efficiencies have increased from 1.1% in 1998 to greater than 25% in the latest scaled-up version of a Toroidal coil chromatography (TCC) instrument working at 240 g.
Collapse
Affiliation(s)
- Ian Sutherland
- Brunel Institute for Bioengineering, Brunel University, Kingston Lane, Uxbridge, Middlesex UB83PH, UK.
| | | | | |
Collapse
|
16
|
van den Heuvel RN, König CS. Improved g-level calculations for coil planet centrifuges. J Chromatogr A 2011; 1218:6038-43. [DOI: 10.1016/j.chroma.2011.06.059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 05/24/2011] [Accepted: 06/13/2011] [Indexed: 10/18/2022]
|
17
|
Guan YH, van den Heuvel R. The three-dimensional model for helical columns on type-J synchronous counter-current chromatography. J Chromatogr A 2011; 1218:5108-14. [PMID: 21684548 DOI: 10.1016/j.chroma.2011.05.078] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Accepted: 05/19/2011] [Indexed: 11/17/2022]
Abstract
Unlike the existing 2-D pseudo-ring model for helical columns undergoing synchronous type-J planetary motion of counter-current chromatograph (CCC), the 3-D "helix" model developed in this work shows that there is a second normal force (i.e. the binormal force) applied virtually in the axial direction of the helical column. This force alternates in the two opposite directions and intensifies phase mixing with increasing the helix angle. On the contrary, the 2-D spiral column operated on the same CCC device lacks this third-dimensional mixing force. The (principal) normal force quantified by this "helix" model has been the same as that by the pseudo-ring model. With β>0.25, this normal centrifugal force has been one-directional and fluctuates cyclically. Different to the spiral column, this "helix" model shows that the centrifugal force (i.e. the hydrostatic force) does not contribute to stationary phase retention in the helical column. Between the popular helical columns and the emerging spiral columns for type-J synchronous CCC, this work has thus illustrated that the former is associated with better phase mixing yet poor retention for the stationary phase whereas the latter has potential for better retention for the stationary phase yet poor phase mixing. The methodology developed in this work may be regarded as a new platform for designing optimised CCC columns for analytical and engineering applications.
Collapse
Affiliation(s)
- Y H Guan
- Brunel Institute for Bioengineering, Brunel University West London, Uxbridge, Middlesex UB8 3PH, UK.
| | | |
Collapse
|
18
|
Yang Y, Gu D, Aisa HA, Ito Y. Studies on the performance of different coiled column configurations for compact type-I countercurrent chromatography. J Sep Sci 2011; 34:1205-11. [PMID: 21491597 DOI: 10.1002/jssc.201100019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 02/23/2011] [Accepted: 02/24/2011] [Indexed: 11/06/2022]
Abstract
Three types of novel coiled column configurations, i.e. a triangular coiled column and elliptical coiled columns I and II, were designed for type-I countercurrent chromatography and their performances were evaluated with two solvent systems each with suitable test samples. Three dinitrophenyl (DNP) amino acids (DNP-DL-glu, DNP-β-ala and DNP-L-ala) were separated with a moderately hydrophobic two-phase solvent system composed of hexane-ethyl acetate-metanol-0.1 M hydrochloric acid (1:1:1:1, v/v), while two dipeptides (tryptophyl-tyrosine and valyl-tyrosine) were separated with a polar solvent system composed of 1-butanol-acetic acid-water (4.75:0.25:5, v/v). The overall results indicated that the performance of compact type-I countercurrent chromatography was improved by elliptical coiled column I which was mounted with its maximum coil diameter perpendicular to the surface of the column holder. Hydrodynamic effects involved in these separations were discussed.
Collapse
Affiliation(s)
- Yi Yang
- Bioseparation Technology Laboratory, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1762, USA
| | | | | | | |
Collapse
|
19
|
Guan Y, Fisher D, Sutherland I. Protein separation using toroidal columns by type-J synchronous counter-current chromatography towards preparative separation. J Chromatogr A 2010; 1217:3525-30. [DOI: 10.1016/j.chroma.2010.03.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 03/13/2010] [Accepted: 03/22/2010] [Indexed: 11/29/2022]
|
20
|
Wood PL. Critical β-values of all coil planet centrifuges. J Chromatogr A 2010; 1217:1283-92. [DOI: 10.1016/j.chroma.2009.12.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 11/15/2009] [Accepted: 12/14/2009] [Indexed: 11/16/2022]
|