Physicochemical characterization of lipopolysaccharide from Salmonella typhi

Dezelić, N; Pende, B; Deželić, Gjuro

doi:10.1016/0926-6585(66)90265-2

Cited by 17 publications

(18 citation statements)

References 6 publications

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“…Scattered intensities were measured on a Fica-50 light-scattering photometer in an angular range from 30 to 150° using vertically polarized light of 436 and 546 nm wavelengths. Benzene at 25 °C was used as the reference liquid, whose Rayleigh ratio was taken to be 46.5 × 10 -6 cm -1 for 436 nm and 16.1 × 10 -6 cm -1 for 546 nm . Its depolarization ratio was determined to be 0.41 and 0.40 for 436 and 546 nm, respectively, by the method of Rubingh and Yu …”

Section: Methodsmentioning

confidence: 99%

Light-Scattering and Phase-Separation Studies on Cyclohexane Solutions of Four-Arm Star Polystyrene

et al. 1998

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Light-scattering and phase-separation experiments were performed on cyclohexane solutions of four narrow-distribution samples of four-arm star polystyrene with molecular weights of 8.5 × 104 to 1.4 × 106, and the results were compared with literature data for linear polystyrene in cyclohexane. The upper critical solution temperatures T c for the star polymer were systematically lower than those for the linear polymer, showing a considerable effect of chain branching on phase separation. The apparent second virial coefficients J of light scattering for the two polymers, plotted against φ/P 0.1 at a fixed temperature below ϑ, happened to form a composite curve at high polymer concentrations, regardless of the relative degree of polymerization P (φ denotes the polymer volume fraction), whereas they appreciably differed at low concentrations, reflecting the finding that the (true) second virial coefficient for the star polymer is significantly larger than that for the linear polymer below ϑ. The chemical potentials of the solvent and solute components derived from the J data were shown to explain the phase diagrams of the two systems fairly well. Thus it was concluded that the difference in T c between four-arm star and linear polystyrenes arises primarily from the difference in J in dilute solution.

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Section: Methodsmentioning

confidence: 99%

Light-Scattering and Phase-Separation Studies on Cyclohexane Solutions of Four-Arm Star Polystyrene

et al. 1998

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“…For a calibration of the apparatus, the intensity of light scattered from pure benzene was measured at 25.0 C at a scattering angle of 90 , where the Rayleigh ratio R Uu (90 ) of pure benzene was taken as 46:5 Â 10 À6 cm À1 . 10 The depolarization ratio u of pure benzene at 25.0 C was determined to be 0:41 AE 0:01. Scattered intensity was measured at seven or eight different concentrations and at scattering angles ranging from 30.0 to 142.5 , and then converted to the excess unpolarized (Uv) components ÁR Uv of the reduced scattered intensity by the use of the scattered intensity from the solvent methanol.…”

Section: Light Scatteringmentioning

confidence: 99%

Characterization of Linear Poly(N-isopropylacrylamide) and Cloud Points in its Aqueous Solutions

et al. 2009

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The second virial coefficient A 2 and intrinsic viscosity [] were determined in methanol at 25.0 C for poly(Nisopropylacrylamide) (PNIPA) samples synthesized by living anionic polymerization in the range of weight-average molecular weight M w from 4:91 Â 10 3 to 7:23 Â 10 4 , which are called L samples, and also for those by radical polymerization in tert-butanol and benzene by the use of azobis(isobutyronitrile) as an initiator in the range of M w from 1:23 Â 10 4 to 7:83 Â 10 4 , which are called T and B samples, respectively. It is found for both A 2 and [] that their values for the three kinds of samples agree well with each other in the range of M w. 3 Â 10 4 but deviate from each other as M w is increased from 3 Â 10 4 , the value for the L sample being the largest and that for the B sample the smallest. The result is consistent with the fact that the average chain dimension is the largest for the L sample having no branch point and the smallest for the B sample having the largest number of branch points. From a simultaneous analysis of A 2 and [] for the L samples on the basis of the Kratky-Porod wormlike chain with excluded volume, the stiffness parameter À1 is estimated to be 18 Å , which is almost the same as those determined for typical flexible polymers. For the L samples, the cloud point was also determined in their aqueous solutions in the range of the weight fraction w of PNIPA from ca. 0.5 to ca. 10%. It is found that the cloud point in the range of w & 2% decreases from ca. 32 C to ca. 18 C as M w is decreased from 7:23 Â 10 4 to 5:47 Â 10 3. Such behavior may be regarded as arising from effects of hydrophobic chain end groups of the L samples.

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“…For a calibration of the apparatus, the intensity of light scattered from pure benzene was measured at 25.0°C at a scattering angle of 90°, where the Rayleigh ratio R Uu(90°) of pure benzene was taken as 46.5 × 10 -6 cm -1 . 18 The depolarization ratio Fu of pure benzene at 25.0°C was determined to be 0.41 ( 0.01. Scattered intensities were measured at five or six different concentrations and at scattering angles ranging from 22.5 to 150°.…”

Section: Introductionmentioning

confidence: 99%

Mean-Square Radius of Gyration of Oligo- and Poly(α-methylstyrene)s in Dilute Solution

2000

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The mean-square radius of gyration 〈S 2 〉 was determined from small-angle X-ray and light scattering measurements for 20 samples of atactic oligo-and poly(R-methylstyrene)s (a-PRMS), each with the fraction of racemic diads fr ) 0.72, in the range of weight-average molecular weight from 6.48 × 10 2 (pentamer) to 3.22 × 10 6 in cyclohexane at 30.5°C (Θ). The ratio 〈S 2 〉/xw as a function of the weightaverage degree of polymerization xw first increases steeply for xw j 20, then passes through a flat hump at xw = 40, and finally approaches its asymptotic value for xw J 1 ×10 3 . On the basis of the helical wormlike (HW) chain model the HW model parameters are λ -1 κ0 ) 3.0, λ -1 τ0 ) 0.9, λ -1 ) 46.8 Å, and ML ) 39.8 Å -1 , where κ0 and τ0 are the differential-geometrical curvature and tortion, respectively, of the characteristic helix of the HW chain taken at the minimum zero of its elastic energy, λ -1 is the stiffness parameter, and ML is the shift factor defined as the molecular weight per unit contour length of the chain. The local chain conformations of a-PRMS are discussed in detail on the basis of the above values of the model parameters and compared with those of atactic polystyrene (fr ) 0.59), atactic poly(methyl methacrylate) (a-PMMA) (fr ) 0.79), and isotactic PMMA (fr = 0.01) previously studied. It is then concluded that the a-PRMS chain tends to retain large and clearly distinguishable helical portions in dilute solution like the a-PMMA chain, as was expected from their chemical structures, although the helical nature of the former is somewhat weaker. To illustrate the situation, pictures are given of representative instantaneous contours of HW Monte Carlo chains for the above four polymers.

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Physicochemical characterization of lipopolysaccharide from Salmonella typhi

Cited by 17 publications

References 6 publications

Light-Scattering and Phase-Separation Studies on Cyclohexane Solutions of Four-Arm Star Polystyrene

Light-Scattering and Phase-Separation Studies on Cyclohexane Solutions of Four-Arm Star Polystyrene

Characterization of Linear Poly(N-isopropylacrylamide) and Cloud Points in its Aqueous Solutions

Mean-Square Radius of Gyration of Oligo- and Poly(α-methylstyrene)s in Dilute Solution

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