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To review current knowledge on the definition of tooth whiteness and its application within dentistry, together with the measured range of tooth colours.'Medline' and 'ISI Web of Sciences' databases were searched electronically with key words tooth, teeth, colour, colour, white and whiteness.The application of colour science within dentistry has permitted the measurement of tooth colour in an objective way, with the most common colour space in current use being the CIELAB (Commission Internationale de l'Eclairage). Indeed, many investigators from a range of different countries have reported L*, a* and b* values for teeth measured in vivo using instrumental techniques such as spectrophotometers, colorimeters and image analysis of digital images. In general, these studies show a large range in L*, a* and b* values, but consistently show that there is a significant contribution of b* value or yellowness in natural tooth colour. Further developments in colour science have lead to the description of tooth whiteness and changes in tooth whiteness based on whiteness indices, with the most relevant and applicable being the WIO whiteness index, a modified version of the CIE whiteness index.

We study the viscoelasticity of surface polymer monolayers by measuring the dynamics of thermal concentration fluctuations with surface light scattering. For various systems of proteins and synthetic polymers we find a semi-dilute regime in which both the elastic and viscous components of the dilational modulus show power law dependencies on the concentration. Surprisingly there is a universal relationship between the exponents for the two components: the viscosity scales with a power double that of the elasticity. These results cannot be explained on the basis of theory developed for bulk systems, and a simple explanation for the singular 2d behavior is suggested., Comment: 4 pages, revtex4, submitted

We have conducted a study of the phase compositions of a ternary solution containing dextran/polyethylene glycol (PEG)/water using UV–visible spectrometry to study the equilibrium behaviour and confocal microscopy to study the dynamic behaviour observed when the system undergoes phase separation driven by the loss of water. Such a study of phase compositions using confocal microscopy is a new development of the technique. In the static experiments, we find a cloud curve, which lies above the coexistence curve on the PEG rich side of the phase diagram, this is found to be in qualitative agreement with calculations of the phase behaviour for a model polydisperse system. In the dynamic experiments, we are able to measure the phase composition using confocal microscopy in the late stages of separation. Here, the compositions lie well inside the coexistence curve at lower drying rates but converge with it at higher drying rates. This is linked to a change in phase morphology: at low rates, a droplet morphology is observed throughout the process whilst at high drying rates a gross phase separation into two layers is observed to occur even at the earliest times probed by the experiment.

The micromechanics of a variety of systems experiencing a structural arrest due to their high density could be unified by a thermodynamic framework governing their approach to ‘jammed’ configurations. The mechanism of supporting an applied stress through the microstructure of these highly packed materials is important in inferring the features responsible for the inhomo- geneous stress transmission and testing the universality for all jammed matter. In this paper, we present a novel method for measuring the force distribution within the bulk of a compressed emulsion system using confocal microscopy and explain our results with a simple theoretical model and computer simulations. We obtain an exponential distribution at large forces and a small peak at small forces, in agreement with previous experimental and simulation data for other particulate systems.

Laser scanning confocal microscopy and image analysis have been used to study the phase separation behavior of ternary solutions of dextran, poly(ethylene glycol), and water during drying. The morphology development is strongly affected by the inhomogeneous nature of the solvent quench and by gravitational sedimentation. A range of transient structures is seen in which the morphology varies with depth into the sample. The origin and development of these structures are explained using simple models. For mixtures where the overall volume fraction of the dextran-rich phase, φs, is 0.1 or 0.34 a droplet morphology is observed whose development is analyzed in detail. The mean radius of the largest droplets is found to increase linearly with time. For mixtures with φs = 0.5, a bicontinuous morphology is seen in which the characteristic length scale decreases with depth into the sample as a result of the inhomogeneous distribution of water in the drying film.

We report experiments utilizing confocal microscopy to determine the position of cornflour starch granules in a paste, as a function of distance from a wall. The granules have an average diameter of 15 mum. If a solvent is chosen such as to approximately match the refractive index of the granules then images of them can be obtained to a depth of 120 mum, which is the limit imposed by the working distance of the x 40 oil immersion lens used in the experiment. An algorithm is presented which successfully identifies the particle centers in 3D. In addition to experiments on static systems we show how measurements of particle number density and velocity can be obtained from images of a system in pipe flow. We find that particles are depleted from the wall over a range of around 100 mum.

We report a method to control the conformation of a weak polyampholyte (the protein $\beta$-casein) in Langmuir monolayers by light, even though the protein is not photosensitive. Our approach is to couple the monolayer state to a photochemical reaction excited in the liquid subphase. The conformational transition of the protein molecule is triggered through its sensitivity to a subphase bulk field (pH in this study), changing in the course of the photochemical process. Thus, reaction of photoaquation of the ferrocyanide ion, which increases the subphase pH from 7.0 to about 8.3, produces a change in the surface monolayer pressure, $\Delta\Pi$, between -0.5 and +1.5 ${\rm mN/m}$ (depending on the surface concentration), signalling a conformational switch. The approach proposed here can be used to selectively target and influence different interfacial properties by light, without embedding photosensitisers in the matrix., Comment: 5 pages, revtex4, to be published in J.Chem.Phys

The ingress of water from various solutions into dense starch and sucrose:starch plaques has been observed over a range of temperatures using stray field nuclear magnetic resonance imaging. Profiles of water content as a function of depth from the surface and sorption time have been analysed to obtain mutual diffusion coefficients. This has been done using the Boltzmann transform and by measuring the front position as a function of time which produces an average mutual diffusion coefficient. This average diffusion coefficient can be fit with an Arrenhius expression with an activation energy of 56 ^ 4 kJ mol 21 . It was found that the average diffusion coefficients for 30:70 and 50:50 sucrose:starch mixtures could be calculated using a weighted mean of the average diffusion coefficients for pure sucrose and pure starch. Although the diffusion coefficients for amorphous and crystalline sucrose are quite different, this has a minor effect on the calculated diffusion coefficients for the range of crystallinities observed in the sucrose:starch mixtures. q 2001 Elsevier Science Ltd. All rights reserved.

The conformational transitions that occur on heating solutions of globular proteins, unfolding and aggregation, were compared with the analogous transitions undergone by proteins adsorbed at interfaces. Fourier transform infrared spectrometry in solution and in the attenuated total reflection geometry revealed, for the globular proteins hen egg lysozyme and bovine serum albumen, both qualitative and quantitative differences between the transitions as they occur in bulk and adsorbed at an interface. In the bulk, unfolding is a sharp transition, followed sequentially on further heating by the relatively sharp onset of the intermolecular association associated with heat set gelation. In contrast, for adsorbed proteins, we found that both processes occur simultaneously over a wide range of temperatures. Proteins were more structurally stable adsorbed at a relatively hydrophilic, solid surface than at a liquid, hydrophobic surface; in the latter case, onset temperatures for both unfolding and intermolecular as...

Collagen VII is the major structural component of the anchoring fibrils that stabilize the cutaneous basement membrane on the dermis. Disruption and, more usually, destruction of the basement membrane are characteristic of wounds that are slow, or fail, to heal, such as chronic lower-limb or pressure ulcers. In this study, the expression of collagen VII was analysed in 28 human chronic cutaneous wounds or scars using a reverse transcription-polymerase chain reaction (RT-PCR) technique. Collagen VII expression was detected in 26 of these 28 cutaneous wounds, but not in two wounds, neither of which showed any clinical evidence of healing.

Results of microfocus X-ray diffraction at the ESRF are presented which provide unique evidence supporting a model for the structure of starch, much of this model having been previously derived only on the basis of circumstantial evidence. Here we present data from ∼2 μm regions within granules which have been subjected to no sample preparation and obtain oriented 2-D fiber patterns from the edge of B-type potato starch granules. This data is in good agreement with that previously calculated by Imberty/Perez1 for a B-type amylose fiber. The peripheral amylopectin helices are oriented in such a way they do not point to a single focus. No discontinuities (“grain boundaries”) within a granule could be found at the 10 μm level of resolution.

Mixtures of deuterated polyethylene oxide with hydrogenous polymethyl methacrylate and hydrogenous polyethylene oxide with deuterated polymethyl methacrylate have been investigated using small angle neutron scattering. The range of temperatures used was 423–473 K and the volume fraction of polyethylene oxide in the mixtures varied from ca. 0.1 to ca. 0.27. Values of the effective interaction parameter ( χ eff ) were obtained using the incompressible random phase approximation. Both temperature dependence and composition dependence were noted in the values of χ eff . The temperature dependence observed was compared with that predicted by equation of state theory. A notable feature of the composition dependence of χ eff was the change in behaviour as temperature increased. Changes in the excess volume of mixing have been cited as a possible source of this behaviour, but the currently available data do not allow us to confirm this. Using the relation between χ eff and a composition independent interaction parameter proposed from Monte Carlo simulations, approximate values of the composition independent interaction parameter have been obtained.

The surface enrichment behavior of blends of perdeuterated poly(methyl methacrylate) with various molecular weights in a high molecular weight hydrogenous poly(methyl methacrylate) matrix has been studied using static secondary ion mass spectrometry and neutron reflectrometry. No significant enrichment was observed in any of these blends, and the results are interpreted in light of available diffusion and thermodynamic data. We conclude that the absence of surface enrichment is due to a low surface energy difference between hydrogenous poly(methyl methacrylate) and deuteropoly(methyl methacrylate) and believe this difference to be in the range 0.00-0.04 mJ m -2 . This is compared to the behavior of the hydrogenous polystyrene/deuteropolystyrene blends where the surface energy difference has been calculated to be 0.08 mJ m -2 .

Mixtures of high-molecular-weight hydrogenous, syndiotactic poly(methyl methacrylate) with two lower-molecular-weight deutero poly(methyl methacrylate)s have been investigated over a range of temperatures and compositions using small-angle neutron scattering. Effective interaction parameters have been obtained which have been used to estimate the Flory-Huggins interaction parameter. Spinodal temperatures have been defined from the temperature dependence of these effective interaction parameters and other parameters of the mixtures. The conclusion is that these isotopic mixtures are incompatible at ambient temperatures and have an upper critical solution temperature. The influence of local stereochemistry on the polymer configuration is evident in the scattering cross-section variation with scattering vector. This variation is compared with the scattering obtained from Monte Carlo rotational isomeric state calculations.

Complex diseases result from contributions of multiple genes that act in concert through pathways. Here we present a method to prioritize novel candidates of disease-susceptibility genes depending on the biological similarities to the known disease-related genes. The extent of disease-susceptibility of a gene is prioritized by analyzing seven features of human genes captured in H-InvDB. Taking rheumatoid arthritis (RA) and prostate cancer (PC) as two examples, we evaluated the efficiency of our method. Highly scored genes obtained included TNFSF12 and OSM as candidate disease genes for RA and PC, respectively. Subsequent characterization of these genes based upon an extensive literature survey reinforced the validity of these highly scored genes as possible disease-susceptibility genes. Our approach, Prioritization ANalysis of Disease Association (PANDA), is an efficient and cost-effective method to narrow down a large set of genes into smaller subsets that are most likely to be involved in the disease pathogenesis.

UV–VIS–NIR and EXAFS spectroscopies have been used to probe the coordination chemistry of cobalt(II) in post-doped silica sol–gel glasses. Materials doped with cobalt(II) chloride, nitrate and acetate were prepared and the cobalt(II) coordination chemistry was studied in relation to post-doping treatments such as dehydration, rehydration and densification. Both octahedral and tetrahedral coordination geometries were observed for the hydrated and dehydrated gel glasses with pronounced anion coordination present in all dehydrated samples. The presence of salts in the gel-glass pore structure provided additional absorbing centres for water. The extent of associated water adsorption (hydrogen bonded to silanol groups and hydrogen bonded to other water molecules) in the pores varied in the order nitrate > chloride > acetate. When the sample was sintered cobalt was incorporated in the glass framework and anions and water were lost.

The direct sequencing of the human type II procollagen (COL2A1) gene from polymerase chain reaction (PCR)-amplified genomic DNA is described. Thirty-two regions of the COL2A1 gene were asymmetrically amplified with intron primers which were specifically chosen to amplify a region spanning 500 to 800 bp of sequence encoding one or more exons and their accompanying intervening sequences. Primers for dideoxynucleotide sequencing of the PCR products were then designed to provide complete exon sequence information and to insure that intron:exon splice junction sequence data would be obtained. Amplification and sequencing reactions were performed on an automated workstation to facilitate the handling of multiple DNA templates. The procedure allowed efficient sequencing of over 25,000 bp of each allele of the COL2A1 gene per diploid genome. We used this method for the comparative analyses of COL2A1 sequences in DNA isolated from the blood of 42 unrelated individuals and we identified 21 neutral sequence variants in the gene. The sequence variations were confirmed by independent assays, including restriction enzyme digestion. The sequence variants described here will be important for identifying haplotypes of the type II procollagen gene that will be useful in defining a genetic etiology for diseases of cartilaginous tissues.

Background Alstrom syndrome is a recessively inherited genetic disorder characterized by congenital retinal dystrophy that leads to blindness, hearing impairment, childhood obesity, insulin resistance, and type 2 diabetes mellitus. We provide new details on cardiologic, hepatic, gastrointestinal, urologic, pulmonary, and neurobehavioral phenotypes in Alstrom syndrome and describe the histopathologic findings in 5 individuals. Methods We obtained data on 182 patients from clinical examinations, medical record reviews, standardized questionnaires, and personal interviews with physicians and parents. Results Dilated cardiomyopathy occurred in 60% of patients. Age at onset was either during infancy, often before vision disturbances were noted, or in adolescence or adulthood. There is a risk of recurrence of infantile cardiomyopathy. Hyperinsulinemia (92%) developed in early childhood and progressed to type 2 diabetes mellitus in 82% of those older than 16 years. Hypertriglyceridemia (54%) precipitated pancreatitis in 8 patients. Urologic dysfunction and gastrointestinal disturbances occurred in 48% and 35% of patients, respectively. Fifty-three percent of patients had persistent pulmonary symptoms. Neurologic symptoms in 20% of patients included clonic tic and absence seizures. Developmental motor or language delays were observed in 46% of patients. Fibrotic infiltrations of multiple organs, that is, kidney, heart, liver, lung, urinary bladder, gonads, and pancreas, were observed. Conclusions The wide-ranging and complex spectrum of phenotypes reported herein broadens those previously described for Alstrom syndrome. These findings will aid physicians in making an early and accurate diagnosis and will help effect appropriate monitoring and treatment.

The in-situ conformations of peptide layers formed from the adsorption of two different synthetic 15-mer peptides at the hydrophilic silicon oxide/aqueous solution interface have been determined using neutron reflectivity (NR). The first peptide is based on the native sequence of a protein-binding domain within a heteromeric transcriptional activator, HAP2, identified from yeast Saccharomyces cerevisiae, with tyrosine (Y) present at the 1st, 8th and 15th amino acid positions, hence we denote this YYY15. Substitution of tryptophan (W) at the same locations gives WWW15. Both peptides have alpha-helical structure in phosphate buffer, as determined by circular dichroism (CD) spectra. D(2)O was used as solvent in the NR experiments to highlight structural heterogeneity across the hydrogenated peptide layers. At pH 7, YYY15 was found to form a weakly adsorbed interfacial monolayer. However, the mutant WWW15 showed strong interfacial adsorption, with the interfacial layer characterized by a middle hydrophobic sublayer of 7-8 A with lower scattering length density and two almost symmetrical hydrophilic outer sublayers of 6-8 A with higher scattering length density, suggesting the formation of a "sideways-on" helical conformation. An increase in pH to 9 resulted in the improved packing within the interfacial layer with similar structure. However, decrease in pH to 5 reduced the interfacial adsorption, mainly due to the enhanced solubility of the peptides associated with the protonation of arginine (R) and lysine (K) groups and the decreasing concentration of divalent HPO(4)(2-) in the phosphate buffer. Subsequent assessment of the reversibility of adsorption showed that once the peptide layers were formed they did not desorb. These interfacial structures may provide feasible routes to interfacial nano-templating.

Surface Quasi-Elastic Light Scattering (SQELS) is an application of dynamic light scattering to measure the dynamics of the thermal roughness of liquid surfaces. An analysis of the spectrum of thermal fluctuations provides information on surface properties like tension and elasticity. In this work we will focus particularly on its use to study polymer or polymer-like Langmuir monolayers. We review work in this area and give an up-to-date overview of the method. Important advances have very recently taken place in the theoretical understanding of this problem, and this has allowed improvements in the analysis of the experimental data. A practical method to estimate the region of physical parameters that can be reliably measured is presented., Comment: 23 pages

The human genome sequence defines our inherent biological potential; the realization of the biology encoded therein requires knowledge of the function of each gene. Currently, our knowledge in this area is still limited. Several lines of investigation have been used to elucidate the structure and function of the genes in the human genome. Even so, gene prediction remains a difficult task, as the varieties of transcripts of a gene may vary to a great extent. We thus performed an exhaustive integrative characterization of 41,118 full-length cDNAs that capture the gene transcripts as complete functional cassettes, providing an unequivocal report of structural and functional diversity at the gene level. Our international collaboration has validated 21,037 human gene candidates by analysis of high-quality full-length cDNA clones through curation using unified criteria. This led to the identification of 5,155 new gene candidates. It also manifested the most reliable way to control the quality of the cDNA clones. We have developed a human gene database, called the H-Invitational Database (H-InvDB; http://www.h-invitational.jp/). It provides the following: integrative annotation of human genes, description of gene structures, details of novel alternative splicing isoforms, non-protein-coding RNAs, functional domains, subcellular localizations, metabolic pathways, predictions of protein three-dimensional structure, mapping of known single nucleotide polymorphisms (SNPs), identification of polymorphic microsatellite repeats within human genes, and comparative results with mouse full-length cDNAs. The H-InvDB analysis has shown that up to 4% of the human genome sequence (National Center for Biotechnology Information build 34 assembly) may contain misassembled or missing regions. We found that 6.5% of the human gene candidates (1,377 loci) did not have a good protein-coding open reading frame, of which 296 loci are strong candidates for non-protein-coding RNA genes. In addition, among 72,027 uniquely mapped SNPs and insertions/deletions localized within human genes, 13,215 nonsynonymous SNPs, 315 nonsense SNPs, and 452 indels occurred in coding regions. Together with 25 polymorphic microsatellite repeats present in coding regions, they may alter protein structure, causing phenotypic effects or resulting in disease. The H-InvDB platform represents a substantial contribution to resources needed for the exploration of human biology and pathology., An international team has systematically validated and annotated just over 21,000 human genes using full-length cDNA, thereby providing a valuable new resource for the human genetics community

Highly porous emulsion-templated materials were synthesized by polymerization of concentrated CO(2)-in-water (C/W) emulsions. The method does not use any organic solvents, in either the synthesis or purification steps, and no solvent residues are left in the materials. It was found that the emulsion stability is strongly affected both by the nature of the surfactant and by the viscosity of the aqueous continuous phase. By optimizing these parameters, it was possible to generate a highly porous, low-density polyacrylamide material with a pore volume of 5.22 cm(3)/g, an average pore diameter of 9.72 microm, and a bulk density of 0.14 g/cm(3). We have broadened the scope of this approach significantly by identifying inexpensive hydrocarbon surfactants to stabilize the C/W emulsions (e.g., Tween 40) and by developing redox initiation routes that allow the synthesis to be carried out at modest temperatures and pressures (20 degrees C, 65 bar). We have also extended the method to the polymerization of monomers such as hydroxyethyl acrylate, which suggests that it is possible to prepare a range of solvent-free biomaterials by this route.

We address experimentally the problem of how the structure of a surface monolayer determines the visco-elasticity of the interface. Optical microscopy and surface quasi--elastic light scattering have been used to characterize aggregation of CaCO$_3$ particles at the air--water interface. The structures formed by cluster-cluster aggregation are two dimensional fractals which grow to eventually form a percolating network. This process is measured through image analysis. On the same system we measure the dynamics of interfacial thermal fluctuations (surface ripplons), and we discuss how the relaxation process is affected by the growing clusters. We show that the structures start damping the ripplons strongly when the two length scales are comparable. No macroscopic surface pressure is measured and this is in contrast to lipid, surfactant or polymer monolayers at concentrations corresponding to surface coverage. This observation and the difficulty in fitting the ripplon spectrum with traditional models suggest that a different physical mechanism might be responsible for the observed damping of ripplons in this system., Comment: 6 pages, submitted to Phys. Rev. E

We have carried out experiments to probe the static and dynamic interfacial properties of $\beta$--casein monolayers spread at the air-buffer interface, and analysed these results in the context of models of weak polyampholytes. Measurements have been made systematically over a wide range of ionic strength and pH. In the semi-dilute regime of surface concentration a scaling exponent, which can be linked to the degree of chain swelling, is found. This shows that at pH close to the isoelectric point, the protein is compact. At pH away from the isoelectric pH the protein is extended. The transition between compact and extended states is continuous. As a function of increasing ionic strength, we observe swelling of the protein at the isoelectric pH but contraction of the protein at pH values away from it. These behaviours are typical of a those predicted theoretically for a weak polyampholyte. Dilational moduli measurements, made as a function of surface concentration exhibit maxima that are linked to the collapse of hydrophilic regions of the protein into the subphase. Based on this data we present a configuration map of the protein configuration in the monolayer. These findings are supported by strain (surface pressure) relaxation measurements and surface quasi-elastic light scattering (SQELS) measurements which suggest the existence of loops and tails in the subphase at higher surface concentrations., Comment: Submitted to J. Chem. Phys

Polygonal meshworks were revealed in the aggregates reconstituted from isolated collagen IV as well as in the lamina densa of mouse pancreas by the quick-freezing and deep-etching technique. Collagen IV solution with acetic acid from the bovine lens capsules and that isolated from the pepsin-solubilized fraction of human placenta reconstituted polygonal meshworks, which were dimensionally similar to the meshwork seen in the lamina densa of mouse pancreas. The average lengths between branching points in the lamina densa, and the meshworks of collagen IV derived from the bovine lens capsules and from the human placenta were 20.1 +/- 7.7 nm (mode = 18 nm), 21.6 +/- 11.3 nm (mode = 14 nm), and 21.6 +/- 9.0 nm (mode = 18 nm), respectively. These observations suggest that collagen IV can, in the absence of other macromolecules including laminins, comprise a skeletal meshwork similar in dimensions to that of the lamina densa.

We derive an analytical approximation in the framework of the radiative transfer theory for use in the analysis of diffuse reflectance measurements. This model uses two parameters to describe a material, the transport free path length, l, and the similarity parameter, s. Using a simple algebraic expression, s and l can be applied for the determination of the absorption coefficient Kabs, which can be easily compared to absorption coefficients measured using transmission spectroscopy. l and Kabs can be seen as equivalent to the S and K parameters, respectively, in the Kubelka‐Munk formulation. The advantage of our approximation is a clear basis in the complete radiative transfer theory. We demonstrate the application of our model to a range of different paper types and to fabrics treated with known levels of a dye.

In particulate materials, such as emulsions and granular media, a "jammed" system results if particles are packed together so that all particles are touching their neighbours, provided the density is sufficiently high. This paper studies through experiment, theory and simulation, the forces that particles exert upon one another in such a jammed state. Confocal microscopy of a compressed polydisperse emulsion provides a direct 3D measurement of the dispersed phase morphology within the bulk of the sample. This allows the determination of the probability distribution of interdroplet forces, P(f) where f is the magnitude of the force, from local droplet deformations. In parallel, the simplest form of the Boltzmann equation for the probability of force distributions predicts P(f) to be of the form e(-f/p), where p is proportional to the mean force f for large forces. This result is in good agreement with experimental and simulated data.

The enthalpy of mixing at 341.45 K of an ethylene-vinyl acetate copolymer mixed with a docosanyl diester of poly(ethylene glycol) has been determined as a function of composition by mixing calorimetry. Endothermic enthalpies were obtained with values in the range 2 to 15 J mol −1 . Small-angle neutron scattering has been used on similar mixtures where the diester was perdeuterated to obtain the effective interaction parameter over the temperature range 353 to 383 K for a volume fraction of ethylene-vinyl acetate copolymer in the mixture from 0.81 to 0.27. The temperature dependence of this effective interaction parameter has been used to obtain the enthalpic contribution. This latter parameter was compared with that obtained from the enthalpy of mixing. Although exact agreement is not obtained, the values are reasonably close and the differences can be attributed to the effect of deuterium labelling on the interaction between the constituents of the polymer blend.

Deuteriopolystyrene of molecular weight ca 32 000 g mol −1 has been functionalized at one end with a fluorocarbon. On mixing this polymer with an unfunctionalized hydrogenous polystyrene a surface excess layer of the deuteriopolymer forms on annealing at 423 K. The surface excess as a function of deuteriopolymer content has been obtained using nuclear reaction analysis and neutron reflectometry, and the shape of the profile from neutron reflectometry alone. From previous secondary ion mass spectral data and by comparison with predictions of surface enrichment theory, it is concluded that the deuteriopolystyrene is tethered by the fluorine label to the air surface. The parameters of this polymer ‘brush’ obtained experimentally are the surface volume fraction of labelled polymer, the brush height, the surface excess and the layer thickness. The surface excess and surface volume fraction of the deuteriopolymer and the adsorption isotherm (surface excess at a function of equilibrium bulk volume fraction) have been compared to the predictions of a self-consistent field theory. Best agreement is obtained with a sticking energy of 1.6 k B T ; however, there appear to be some disparities when compared to the limiting ‘dry’ brush predictions. There is evidence from neutron reflectometry of brush formation before annealing of the polymer films.

The ingress of liquid water and water vapour into glassy pellets of the starch polymer amylose has been studied using stray field nuclear magnetic resonance imaging (STRAFI), to produce one-dimensional water concentration profiles as a function of depth from the sorption surface, and time. For the vapour experiments the observed concentration profiles are characteristic of a system showing Fickian diffusion with a mutual diffusion coefficient, a function of the concentration of the penetrant. In contrast, the ingress of liquid water is non-Fickian; concentration profiles characteristic of Case II diffusion have been modelled semi-quantitatively using the Thomas-Windle model.