Specific Refractive Index Increments of Polymers in Dilute Solution

Michielsen, Stephen

doi:10.1002/0471532053.bra057

Cited by 24 publications

(21 citation statements)

References 779 publications

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“…Refractive index increment for PCL in THF at 25.0 8C, determined with a Knauer 193 differential refractometer, was 0.0786 cm 3 Á g À1 , close to the literature value of 0.0795 cm 3 Á g À1 measured at 35 8C. [32,33] Intrinsic viscosities of PCL in THF were determined at 25.0 8C with an AVS-310 automatic viscometer (Schott Geräte) equipped with an Ubbelohde viscometer type 01/0a. In the calculation of viscosity-average molecular weights, the following Mark-Houwink constants were applied: K ¼ 1.395 Â 10 À5 dm 3 Á g À1 and a ¼ 0.786.…”

Section: Experimental Partsupporting

confidence: 80%

Poly(ε‐caprolactone) Biomaterial Sterilized by E‐Beam Irradiation

Filipczak

Woźniak

Ulański

et al. 2006

Macromolecular Bioscience

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The effects of ionizing radiation (electron beam) on poly(epsilon-caprolactone) (PCL) were studied by analyzing changes in viscosity-average and weight-average molecular weight and radius of gyration, and by performing sol-gel analysis and swelling tests. Samples were irradiated under various conditions: solid and molten PCL in the presence or absence of air. The overall efficiency of crosslinking is higher for samples irradiated in the molten state than in the solid state, and is reduced in the presence of oxygen. Based on three kinds of experiments (molecular weight dependence on the dose in the pre-gelation region, sol-gel analysis, and swelling study), radiation-chemical yields of intermolecular crosslinking and scission were determined and are discussed in terms of the mechanism of radiation-induced reactions in PCL. Properties of the gels formed by high-dose irradiation and mechanical properties of irradiated PCL were analyzed. Irradiation causes an increase in the compression modulus of PCL. This process occurs at the pre-gelation stage and continues in the gel-containing system. We have demonstrated, for the first time, that irradiation of solid PCL is accompanied by a pronounced post-effect, which manifests itself by changes in the average molecular weight. EPR data indicate that this effect, at least in part, is caused by the presence of long-lived radicals trapped in the crystalline regions. Irradiation with the sterilizing dose does not cause a statistically significant change in the biocompatibility of PCL after subsequent storage for 79 d, as determined by preliminary osteoblast vitality tests.

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Section: Experimental Partsupporting

confidence: 80%

Poly(ε‐caprolactone) Biomaterial Sterilized by E‐Beam Irradiation

Filipczak

Woźniak

Ulański

et al. 2006

Macromolecular Bioscience

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“…The system consisted of a guard column (Ultrahydrogel 6 mm=40 mm; Waters, Milford, MA, USA) and two main columns (Ultrahydrogel linear 7.8 mm=300 mm; Waters, Milford, MA, USA) connected in series (Song et al 2008). A dn/dc value of 0.15 ml g -1 for GGM was used in the calculations (Michielsen 1999).…”

Section: Analyses Of Extract Solutionsmentioning

confidence: 99%

Characterisation of Norway spruce hemicelluloses extracted by pressurised hot-water extraction (ASE) in the presence of sodium bicarbonate

Song¹,

Pranovich²,

Holmbom³

2011

Holzforschung

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Ground spruce sapwood was extracted with pressurised hot water with addition of different amounts of sodium bicarbonate (NaHCO 3 ) to find optimal pH conditions for extraction of hemicelluloses, especially of galactoglucomannans (GGMs). The extractions were carried out in an accelerated solvent extractor (ASE) at 1708C. When extraction was carried out with 2.5 mM NaHCO 3 during 60-100 min extraction time (end-pH 3.9), more than 60% of the total extracted substances were hemicellulose-derived carbohydrates. Under these conditions, approximately 80% of the extracted carbohydrates were from GGMs (13% b.o. wood). At higher concentrations of NaHCO 3 , the yield of carbohydrates, especially those derived from GGMs, decreased. Hydrolytic depolymerisation of hemicelluloses occurring during extraction with plain water was largely inhibited in the presence of 2.5-5 mM NaHCO 3 . The hydrolytic deacetylation of GGM was diminished at low NaHCO 3 concentrations but increased dramatically at higher NaHCO 3 concentrations. It can be concluded that 2.5-5 mM NaHCO 3 giving an endpH value of 4 is better for GGM isolation than plain water.

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“…This is because heavy metal stains used in electron microscopy are generally non-specific (Glauert, 1965;Hayat, 1971) and refractive index is linearly proportional to density and relatively independent of the actual molecule (Michielsen, 1999). We have employed the stain density-refractive index relationship because it is the only available method of estimating refractive index at optical wavelengths using non-optical techniques at electron microscopy resolution (Marsili et al, 2004).…”

Section: Image Processingmentioning

confidence: 99%

Analysis of nuclear fiber cell cytoplasmic texture in advanced cataractous lenses from Indian subjects using Debye–Bueche theory

Metlapally

Costello

Gilliland

et al. 2008

Experimental Eye Research

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Alterations in ultrastructural features of the lens fiber cells lead to scattering and opacity typical of cataracts. The organelle-free cytoplasm of the lens nuclear fiber cell is one such component that contains vital information about the packing and organization of crystallins critical to lens transparency. The current work has extended analysis of the cytoplasmic texture to transparent and advanced cataractous lenses from India and related the extent of texturing to the nuclear scattering observed using the Debye-Bueche theory for inhomogeneous materials. Advanced age-related nuclear cataracts (age-range 38-75 years) and transparent lenses (age-range 48-78 years) were obtained following extracapsular cataract removal or from the eye bank, at the L. V. Prasad Eye Institute. Lens nuclei were Vibratome-sectioned, fixed and prepared for transmission electron microscopy using established techniques. Electron micrographs of the unstained thin sections of the cytoplasm were acquired at 6500X and percent scattering for wavelengths 400-700 nm was calculated using the Debye-Bueche theory. Electron micrographs from comparable areas in an oxidative-damage sensitive (OXYS) rat model and normal rat lenses preserved from an earlier study were used, as they have extremely textured and smooth cytoplasms, respectively. The Debye-Bueche theoretical approach produces plots that vary smoothly with wavelength and are sensitive to spatial fluctuations in density. The central lens fiber cells from advanced cataractous lenses from India and the OXYS rat, representing opaque lens nuclei, produced the greatest texture and scattering. The transparent human lenses from India had a smoother texture and less predicted scattering, similar to early cataracts from previous studies. The normal rat lens had a homogeneous cytoplasm and little scattering. The data indicate that this method allowed easy comparison of small variations in cytoplasmic texture and robustly detected differences between transparent and advanced cataractous human lenses. This may relate directly to the proportion of opacification contributed by the packing of crystallins. The percent scattering calculated using this method may thus be used to generate a range of curves with which to compare and quantify the relative contribution of the packing of crystallins to the loss of transparency and scattering observed.

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Specific Refractive Index Increments of Polymers in Dilute Solution

Cited by 24 publications

References 779 publications

Poly(ε‐caprolactone) Biomaterial Sterilized by E‐Beam Irradiation

Poly(ε‐caprolactone) Biomaterial Sterilized by E‐Beam Irradiation

Characterisation of Norway spruce hemicelluloses extracted by pressurised hot-water extraction (ASE) in the presence of sodium bicarbonate

Analysis of nuclear fiber cell cytoplasmic texture in advanced cataractous lenses from Indian subjects using Debye–Bueche theory

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