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Li J, Yang Z, Lin X, Wu S, Li G, Li N, Otter D, Zhu F, Hartinger C, Corke H, Hemar Y. In-flow SAXS investigation of whey protein isolate hydrolyzed by bromelain. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.127662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Small-angle X-ray scattering investigation of the micellar and submicellar forms of bovine casein. J DAIRY RES 2009. [DOI: 10.1017/s0022029900028922] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SummarySmall-angle X-ray scattering was performed on whole casein under submicellar (Ca2+ removed) and micellar (Ca2+ re-added) conditions. Submicellar scattering curves showed two Gaussian components which were interpreted in terms of a spherical particle with two concentric regions of different electron density, a relatively compact core of higher electron density and a looser shell. Normalized scattering curves and calculated distance distribution functions were consistent with this picture. Micellar scattering data, which can yield only cross-sectional information related to a window of scattered intensities, could be analysed by a sum of three Gaussians with no residual function. The two Gaussians with the lower radii of gyration were again taken to indicate the two concentric regions of different electron density of inhomogeneous spherical particles; the third Gaussian was shown to reflect the packing number of these particles within a cross-sectional portion of the micelle, which was 3:1 for this system. These results are a strong indication that submicellar inhomogeneous particles containing hydrophobically stabilized inner cores exist within the colloidal micelle.
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Metwalli E, Moulin JF, Gebhardt R, Cubitt R, Tolkach A, Kulozik U, Müller-Buschbaum P. Hydration behavior of casein micelles in thin film geometry: a GISANS study? LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:4124-4131. [PMID: 19714832 DOI: 10.1021/la802602g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The water content of casein micelle films in water vapor atmosphere is investigated using time-resolved grazing incidence small-angle neutron scattering (GISANS). Initial dry casein films are prepared with a spin-coating method. At 30 degrees C, the formation of a water-equilibrated casein protein film is reached after 11 min with a total content of 0.36 g of water/g of protein. With increasing water vapor temperature up to 70 degrees C, an increase in the water content is found. With GISANS, lateral structures on the nanometer scale are resolved during the swelling experiment at different temperatures and modeled using two types of spheres: micelles and mini-micelles. Upon water uptake, molecular assemblies in the size range of 15 nm (mini-micelles) are attributed to the formation of a high-contrast D2O outer shell on the small objects that already exist in the protein film. For large objects (>100 nm), the mean size increases at high D2O vapor temperature because of possible aggregation between hydrated micelles. These results are discussed and compared with various proposed models for casein micelle structures.
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Affiliation(s)
- E Metwalli
- Technische Universität München, Physik Department E13, James-Franck-Str.1, 85747 Garching, Germany
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Baussay K, Nicolai T, Durand D. Effect of the Cluster Size on the Micro Phase Separation in Mixtures of β-Lactoglobulin Clusters and κ-Carrageenan. Biomacromolecules 2005; 7:304-9. [PMID: 16398529 DOI: 10.1021/bm050662m] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The phase separation of globular protein clusters formed by heat-denatured beta-lactoglobulin (beta-lg) in mixtures with the polysaccharide kappa-carrageenan (kappa-car) has been studied at pH 7 and 20 degrees C. The effect of the protein cluster size on the phase separation was investigated by preparing clusters with radii between 20 nm and 1 mum. The formation of protein rich microdomains led to an increase of the turbidity starting at a minimum kappa-car concentration that decreased with increasing cluster size, but was only weakly dependent on the protein concentration. The size and number of microdomains do not depend much on the cluster size, but their density decreases with increasing cluster size leading to a lower turbidity.
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Affiliation(s)
- Karine Baussay
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
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Pouzot M, Nicolai T, Visschers R, Weijers M. X-ray and light scattering study of the structure of large protein aggregates at neutral pH. Food Hydrocoll 2005. [DOI: 10.1016/j.foodhyd.2004.06.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Baussay K, Bon CL, Nicolai T, Durand D, Busnel JP. Influence of the ionic strength on the heat-induced aggregation of the globular protein beta-lactoglobulin at pH 7. Int J Biol Macromol 2005; 34:21-8. [PMID: 15178005 DOI: 10.1016/j.ijbiomac.2003.11.003] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/19/2003] [Indexed: 11/29/2022]
Abstract
The influence of the ionic strength on the structure of beta-lactoglobulin aggregates formed after heating at pH 7 has been studied using static and dynamic light scattering. The native protein depletion has been monitored using size exclusion chromatography. Above a critical association concentration (CAC) well-defined clusters are formed containing about 100 monomers. The CAC increases with decreasing ionic strength. The so-called primary aggregates associate to form self similar semi-flexible aggregates with a large scale structure that is only weakly dependent on the ionic strength. The local density of the aggregates increases with increasing ionic strength. At a critical gel concentration, Cg, the size of the aggregates diverges. Cg decreases from 100 g/l without added salt to 1 g/l at 0.4M NaCl. For C > Cg the system gels except at high ionic strength close to Cg where the gels collapse under gravity and a precipitate is formed.
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Affiliation(s)
- Karine Baussay
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, Av. Olivier Messiaen 72085 Le Mans Cedex 9, France
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Pouzot M, Durand D, Nicolai T. Influence of the Ionic Strength on the Structure of Heat-Set Globular Protein Gels at pH 7. β-Lactoglobulin. Macromolecules 2004. [DOI: 10.1021/ma048919g] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthieu Pouzot
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Dominique Durand
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Taco Nicolai
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
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Pouzot M, Nicolai T, Durand D, Benyahia L. Structure Factor and Elasticity of a Heat-Set Globular Protein Gel. Macromolecules 2003. [DOI: 10.1021/ma035117x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Matthieu Pouzot
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Taco Nicolai
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Dominique Durand
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
| | - Lazhar Benyahia
- Polymères, Colloïdes, Interfaces, UMR CNRS, Université du Maine, 72085 Le Mans Cedex 9, France
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Gun'ko VM, Klyueva AV, Levchuk YN, Leboda R. Photon correlation spectroscopy investigations of proteins. Adv Colloid Interface Sci 2003; 105:201-328. [PMID: 12969646 DOI: 10.1016/s0001-8686(03)00091-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Physical principles of photon correlation spectroscopy (PCS), mathematical treatment of the PCS data (converting autocorrelation functions to distribution functions or average characteristics), and PCS applications to study proteins and other biomacromolecules in aqueous media are described and analysed. The PCS investigations of conformational changes in protein molecules, their aggregation itself or in consequence of interaction with other molecules or organic (polymers) and inorganic (e.g. fumed silica) fine particles as well as the influence of low molecular compounds (surfactants, drugs, salts, metal ions, etc.) reveal unique capability of the PCS techniques for elucidation of important native functions of proteins and other biomacromolecules (DNA, RNA, etc.) or microorganisms (Escherichia coli, Pseudomonas putida, Dunaliella viridis, etc.). Special attention is paid to the interaction of proteins with fumed oxides and the impact of polymers and fine oxide particles on the motion of living flagellar microorganisms analysed by means of PCS.
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Affiliation(s)
- Vladimir M Gun'ko
- Institute of Surface Chemistry, 17 General Naumov Street, Kiev 03164, Ukraine.
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Sagis LM, Veerman C, Ganzevles R, Ramaekers M, Bolder SG, van der Linden E. Mesoscopic structure and viscoelastic properties of β-lactoglobulin gels at low pH and low ionic strength. Food Hydrocoll 2002. [DOI: 10.1016/s0268-005x(01)00084-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Le Bon C, Durand D, Nicolai T. Influence of genetic variation on the aggregation of heat-denatured β-lactoglobulin. Int Dairy J 2002. [DOI: 10.1016/s0958-6946(02)00056-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12
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Nicolai T, Urban C, Schurtenberger P. Light Scattering Study of Turbid Heat-Set Globular Protein Gels Using Cross-Correlation Dynamic Light Scattering. J Colloid Interface Sci 2001; 240:419-424. [PMID: 11482949 DOI: 10.1006/jcis.2001.7672] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The structure factor of aqueous solutions of the globular protein beta-lactoglobulin was determined as a function of heating time at 76 degrees C. We show how the effect of multiple scattering on the scattered light intensity can be effectively corrected using cross-correlation dynamic light scattering even if the transmission is only 1%. The structure factor of aggregated and gelled proteins can be described by the Ornstein-Zernike equation. The system is characterized by a correlation length that increases with heating time and stabilizes some time after the gel is formed. The correlation length of the protein gels decreases with decreasing concentration. Measurements after progressive dilution of a sample close to the gel point showed that the protein aggregates are initially interpenetrated and disinterpenetrate upon dilution. Copyright 2001 Academic Press.
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Affiliation(s)
- Taco Nicolai
- Polyméres, Colloides, Interfaces, UMR-CNRS, Université du Maine, Le Mans Cedex 9, 72085, France
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Croguennoc P, Nicolai T, Kuil ME, Hollander JG. Self-diffusion of Native Proteins and Dextran in Heat-set Globular Protein Gels. J Phys Chem B 2001. [DOI: 10.1021/jp0043726] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Le Bon C, Nicolai T, Kuil ME, Hollander JG. Self-Diffusion and Cooperative Diffusion of Globular Proteins in Solution. J Phys Chem B 1999. [DOI: 10.1021/jp991345a] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Bon C, Nicolai T, Durand D. Growth and structure of aggregates of heat-denatured beta-Lactoglobulin. Int J Food Sci Technol 1999. [DOI: 10.1046/j.1365-2621.1999.00310.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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16
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Le Bon C, Nicolai T, Durand D. Kinetics of Aggregation and Gelation of Globular Proteins after Heat-Induced Denaturation. Macromolecules 1999. [DOI: 10.1021/ma9905775] [Citation(s) in RCA: 140] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Christel Le Bon
- Chimie-Physique des Matériaux Polymères, UMR-CNRS 6515, Université du Maine Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Taco Nicolai
- Chimie-Physique des Matériaux Polymères, UMR-CNRS 6515, Université du Maine Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
| | - Dominique Durand
- Chimie-Physique des Matériaux Polymères, UMR-CNRS 6515, Université du Maine Avenue Olivier Messiaen, 72085 Le Mans Cedex 9, France
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Monahan FJ, McClements DJ, German JB. Disulfide-mediated polymerization of whey proteins in whey protein isolate-stabilized emulsions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1997; 415:127-36. [PMID: 9131188 DOI: 10.1007/978-1-4899-1792-8_10] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The effects of protein polymerization in whey protein isolate-stabilized emulsions on emulsion properties were investigated. Polymerization, involving intermolecular disulfide bonds between whey proteins adsorbed at the oil-water interface, increased with increasing storage time following emulsion formation. Ageing resulted in increased aggregation of emulsion droplets, emulsion viscosity and susceptibility to creaming but these effects were lower when thiol-disulfide interchange reactions were inhibited by N-ethylmaleimide (NEM). Following heating to 75 degrees C, disulfide-mediated polymerization of whey proteins increased as did droplet aggregation, emulsion viscosity and creaming. While NEM lowered the extent of disulfide-mediated polymerization it did not affect the measured physical properties of the heated emulsions. Non-covalent interactions appeared to be the principal forces leading to aggregation of emulsion droplets but aggregates once formed were stabilized by disulfide bonds.
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Affiliation(s)
- F J Monahan
- Department of Food Science, University College, Dublin, Belfield, Ireland
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Kumosinski TF, King G, Farrell HM. Comparison of the three-dimensional molecular models of bovine submicellar caseins with small-angle X-ray scattering. Influence of protein hydration. JOURNAL OF PROTEIN CHEMISTRY 1994; 13:701-14. [PMID: 7710660 DOI: 10.1007/bf01886953] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
To test the applicability of two energy-minimized, three-dimensional structures of the bovine casein submicelle, theoretical small-angle X-ray scattering curves in the presence and absence of water were compared to experimental data. The published method simulates molecular dynamics of proteins in solution by employing adjustable Debye-Waller temperature factors (B factors) for the protein, for the solvent, and for protein-bound water. The programs were first tested upon bovine pancreatic trypsin inhibitor beginning with its known X-ray crystal structure. To approximate the degree of protein hydration previously determined by NMR relaxation experiments (0.01 g water/g protein), 120 water molecules were docked into the large void of the kappa-casein portion of the structure for both the symmetric and asymmetric casein submicelle models. To approximate hydrodynamic hydration (0.244 g water/g protein), 2703 water molecules were added to each of the above structures using the "droplet" algorithm in the Sybyl molecular modeling package. All structures were then energy-minimized and their solvation energies calculated. Theoretical small-angle X-ray scattering curves were calculated for all unhydrated and hydrated structures and compared with experimentally determined scattering profiles for submicellar casein. Best results were achieved with the 120-bound-water structure for both the symmetric and asymmetric submicelle models. Comparison of results for the protein submicelle models with those for the theoretical and literature values of bovine pancreatic trypsin inhibitor demonstrates the applicability of the methodology.
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Affiliation(s)
- T F Kumosinski
- USDA, ARS, Eastern Regional Research Center, Philadelphia, Pennsylvania 19118, USA
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Farrell H, Pessen H, Brown E, Kumosinski T. Structural Insights into the Bovine Casein Micelle: Small Angle X-Ray Scattering Studies and Correlations with Spectroscopy. J Dairy Sci 1990. [DOI: 10.3168/jds.s0022-0302(90)79062-5] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Pessen H, Kumosinski TF, Farrell HM. Water interactions in bovine casein: 2H NMR relaxation and small-angle X-ray scattering studies. BASIC LIFE SCIENCES 1990; 56:175-97. [PMID: 2078171 DOI: 10.1007/978-1-4684-5868-8_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- H Pessen
- ERRC, USDA, Philadelphia, PA 19118
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Kumosinski TF, Pessen H, Farrell HM, Brumberger H. Determination of the quaternary structural states of bovine casein by small-angle X-ray scattering: submicellar and micellar forms. Arch Biochem Biophys 1988; 266:548-61. [PMID: 3190243 DOI: 10.1016/0003-9861(88)90288-3] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Whole casein occurs in milk as a spherical colloidal complex of protein and salts called the casein micelle, with approximate average radii of 650 A as determined by electron microscopy. Removal of Ca2+ is thought to result in dissociation into smaller noncolloidal protein complexes called submicelles. Hydrodynamic and light scattering studies on whole casein submicelles suggest that they are predominantly spherical particles with a hydrophobic core. To investigate whether the integrity of a hydrophobically stabilized submicellar structure is preserved in the electrostatically stabilized colloidal micellar structure, small-angle X-ray scattering (SAXS) experiments were undertaken on whole casein from bovine milk under submicellar (without Ca2+) and micellar (with added 10 mM CaCl2) conditions. All SAXS results showed multiple Gaussian character and could be analyzed best by nonlinear regression in place of the customary Guinier plot. Analysis of the SAXS data for submicellar casein showed two Gaussian components which could be interpreted in terms of a particle with two concentric regions of different electron density, designated as a "compact" (subscript C) core and a "loose" (subscript L) shell, respectively. The submicelle was found to have an average molecular weight of 285,000 +/- 14,600 and a mass fraction of higher electron density core, k, of 0.212 +/- 0.028. The radius of gyration of the core, RC, was 37.98 +/- 0.01 A with an electron density difference, delta rho C, of 0.0148 +/- 0.0014 e-/A3, while the loose region had values of RL = 88.2 +/- 0.8 A with delta rho L = 0.0091 +/- 0.0003 e-/A3. Calculated distance distribution functions and normalized scattering curves also were consistent with an overall spherical particle with a concentric spherical inner core of higher electron density. These results, and in particular the remarkably low electron densities of the shells, can be interpreted in terms of a loosely packed spherical aggregate stabilized by a hydrophobic inner core and surrounded by an even more loosely packed hydrophilic region, in agreement with the results of other studies. The SAXS data for the colloidal micellar casein, which yield only cross-sectional information related to a window of scattered intensity, were analyzed by a sum of three Gaussians with no residual function. The two Gaussians with the lower values of the radius of gyration were interpreted again as an indication of an inhomogeneous spherical particle of two electron densities with the same centroid.(ABSTRACT TRUNCATED AT 400 WORDS)
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Affiliation(s)
- T F Kumosinski
- U.S. Department of Agriculture, Eastern Regional Research Center, Philadelphia, Pennsylvania 19118
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