Charge Mediated Changes to the Intrinsic Viscosity of Biopolymer Systems.

A theoretical approach is presented to quantify the effect of ionic strength on the swelling and shrinkage of the hydrodynamic coil size of a generic biopolymer. This was conducted in view of extraction methods that often utilize acids and alkali combinations and, therefore, invariably impact the levels of salt found in commercially available biopolymers. This approach is supplemented by intrinsic viscosity measurements for the purpose of validation across a variety of biopolymer architectures, type of functionalization, as well as the quoted molar mass.

Using the Herschel-Bulkley Consistency Index to Characterise Complex Biopolymer Systems-The Effect of Screening.

The use of the consistency index, as determined from fitting rheological data to the Herschel-Bulkley model, is described such that it may yield systematic trends that allow a very convenient description of the dissipative flow properties of linear and branched (bio)polymers in general, both in molecular and weakly associated supramolecular solutions. The effects of charge-mediated interactions by the systematic variation of the ionic strength and hydrogen bonding by a systematic variation in pH, using levels that are frequently encountered in systems used in practice, is investigated. These effects are then captured using the associated changes in the intrinsic viscosity to highlight the above-mentioned trends, while it also acts as an internal standard to describe the data in a concise form.

Role of Molecular Water Layer State on Freezing Front Propagation Rate and Mode Studied with Thermal Imaging.

In this work, we study the relationship between the molecular water layer (MWL) and frost freezing onset and propagation. The progression of frost has been reported to be governed by various localized icing phenomena, including interdroplet ice bridging, dry zones, and frost halos. Reports studying the state of water on surfaces have revealed the presence of a thin nanometer water layer on a range of surfaces.

Patella height measurements in patients with patellofemoral instability: the power to predict patella height indices.

Introduction: Numerous indices for patella height measurement are described in the literature; however, there is not a universally accepted 'gold standard'. Choice of indices varies depending on personal preference and previous experience, making it difficult to compare results between studies. The aims of this study were to assess the correlation between different patella height indices and generate statistically derived formulae that can be used to predict the value of one patella height ratio when another is known.

Affine Deformation and Self-Assembly Alignment in Hydrogel Nanocomposites.

Tailoring the order in hierarchical structures is a key goal of bioinspired nanocomposite design. Recently, nacre-like materials have been developed by solvent evaporation methods that are scalable and attain advanced functionalities. However, understanding the alignment mechanisms of 2D fillers, nanosheets, or platelets remains challenging.

Systematic Study of the Nanostructures of Exfoliated Polymer Nanocomposites.

High-performance bioinspired materials have shown rapid development over the last decade. Examples are brick-and-mortar hierarchical structures, which are often achieved via solvent evaporation. Although good properties are claimed, most systems are composed of stacked or intercalated platelets.

Design Rules for Binary Bisamide Gelators: toward Gels with Tailor-Made Structures and Properties.

This study intends to develop design rules for binary mixture of gelators that govern their assembly behavior and subsequently explore the impact of their supramolecular assembly patterns on the gels' rheological properties. To achieve these goals, BA gelators with odd and even parities [-methylene spacers between the amide groups ( = 5-10) and 17 carbons at each end] were blended at different ratios. Such bisamides with simple structures were selected to study because their different spacer lengths offer the possibility to have matching or non-matching hydrogen bonds.

Supramolecular Arrangement and Rheological Properties of Bisamide Gels.

We report a systematic study of the gelation behavior of BA gelators in xylene, with odd and even -methylene spacers between the amide groups ( = 5-10) and 17 carbons at each end. The melting temperatures () of BA gels are obtained from fitting our DSC(T) model to the experimental DSC data. The found of BA gels is about 35 °C lower than of the pure BA gelators.

The Glass Transition Temperature of Heterogeneous Biopolymer Systems.

Biopolymers are abundant, renewable, and biodegradable resources. However, bio-based materials often require toughening additives, like (co)polymers or small plasticizing molecules. Plasticization is monitored via the glass transition temperature versus diluent content.

Iron and Manganese Alginate for Rechargeable Battery Electrodes.

We present a sustainable, inherently safe battery chemistry that is based on widely available and cheap materials, that is, iron and manganese hosted in alginate bio-material known from the food and medical industry. The resulting battery can be recycled to allow circularity. The electrodes were synthesised by the alginate caging the multi-valent metals to form a hydrogel in an aqueous environment.

Molecular Arrangement and Thermal Properties of Bisamide Organogelators in the Solid State.

The crystal structure and phase behavior of bisamide gelators are investigated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and molecular modeling, aiming at a better understanding of bisamide gel systems. A homologous series of bisamide model compounds (BAs) was prepared with the (CH) spacer between the two amide groups, where varies from 5 to 10, and with two symmetric C17 alkyl tails. With increasing spacer length, the thermal properties show a clear odd-even effect, which was characterized using our newly developed analytical model DSC(T).

Inter- and intra-rater reliability of knee flexion angle measurements on X-ray and MRI.

Background: Range of motion (ROM) is an important aspect of orthopaedic patient assessment. It can be measured at the knee joint by determining the knee flexion angle (KFA) a patient can achieve at extremes of flexion and extension. As with any measurement, the accuracy and reliability of the method used determine its validity.

Inter- and intra-observer reliability of patellar height measurements in patients with and without patellar instability on plain radiographs and magnetic resonance imaging.

Introduction: Many patella height indices exist in the literature. There is no single universally accepted radiological assessment for measuring patella height. The aims of this study were to determine which of the commonly used indices can most reliably measure patella height and compare the findings on both plain X-ray and magnetic resonance imaging (MRI) of the knee.

Environmentally Sensitive Luminescence Reveals Spatial Confinement, Dynamics, and Their Molecular Weight Dependence in a Polymer Glass.

Polymer glasses have an irregular structure. Among the causes for such complexity are the chemically distinct chain end groups that are the most abundant irregularities in any linear polymer. In this work, we demonstrate that chain end induced defects allow polymer glasses to create confined environments capable of hosting small emissive molecules.

Irreversible Shear-Activated Gelation of a Liquid Crystalline Polyelectrolyte.

We report irreversible, shear-activated gelation in liquid crystalline solutions of a rigid polyelectrolyte that forms rodlike assemblies (rods) in salt-free solution. At rest, the liquid crystalline solutions are kinetically stable against gelation and exhibit low viscosities. Under steady shear at, or above, a critical shear rate, a physically cross-linked, nematic gel network forms due to linear growth and branching of the rods.

Observation of transition cascades in sheared liquid crystalline polymers.

We report on the shear rheology of liquid crystalline solutions composed of charged, rodlike polymers that form supramolecular assemblies dispersed in water. Under steady shear, we observe shear thickening behavior, followed by a hesitation in the viscosity accompanied by an extremely narrow range of negative first normal stress difference. The Peclet number (Pe, shear rate normalized by rod rotational diffusivity) for the onset of shear thickening is in agreement with previous, high-resolution numerical simulations of the Doi-Edwards-Hess kinetic theory.

The Effect of Magnetic Field on Catalytic Properties in Core-Shell Type Particles.

Magnetic field effects can provide a handle on steering chemical reactions and manipulating yields. The presence of a magnetic field can influence the energy levels of the active species by interacting with their spin states. Here we demonstrate the effect of a magnetic field on the electrocatalytic processes taking place on platinum-based nanoparticles in fuel cell conditions.

A deconvolution protocol of the mechanical relaxation spectrum to identify and quantify individual polymer feature contributions to self-healing.

Starting from experimental macro-rheological data, we develop a fitting protocol that succeeded in the separation of the overlapping relaxation phenomena in the dissipative regime for a set of intrinsic healing polymers healing most effectively near their glass transition temperature Tg. To allow for a proper deconvolution, the rheological master curves are converted to a relaxation spectrum (H(τ)) and this is fitted using an optimized mechanical model, e.g.

The effect of lattice strain on catalytic activity.

We report on the effect of lattice strain in three different types of core-shell electrocatalyst particles on their catalytic activity towards the oxygen reduction reaction. We decouple the changes in catalytic activity with respect to a geometrical and an energetic contribution, both of electronic origin.

Rheological investigation of specific interactions in Na Alginate and Na MMT suspension.

Here we report on a study of a rheological behavior of sodium alginate and montmorillonite suspension. We find that viscoelastic behavior of this suspension is dramatically affected with increasing volume fraction of montmorillonite platelets. Addition of montmorillonite generally leads to gel formation, which is attributed to interactions of montmorillonite and alginate via H-bonding and attraction between the positive edges of the platelets and the anionic backbone of the biopolymer.

On the "tertiary structure" of poly-carbenes; self-assembly of sp3-carbon-based polymers into liquid-crystalline aggregates.

The self-assembly of poly(ethylidene acetate) (st-PEA) into van der Waals-stabilized liquid-crystalline (LC) aggregates is reported. The LC behavior of these materials is unexpected, and unusual for flexible sp(3)-carbon backbone polymers. Although the dense packing of polar ester functionalities along the carbon backbone of st-PEA could perhaps be expected to lead directly to rigid-rod behavior, molecular modeling reveals that individual st-PEA chains are actually highly flexible and should not reveal rigid-rod induced LC behavior.

Supramolecular "leeks" of a fluorinated hybrid amphiphile that self-assembles into a disordered columnar phase.

We report on the formation of unprecedented "leek"-shaped aggregates of an anionic fluoroalkyl sulfonate surfactant (FS) and the supramolecular assembly of these aggregates into a disordered columnar phase (CS). The leeks are formed by wrapping of 2-4 FS-water bilayers of thickness 26-28 Å into 10-20 nm thick and >100 nm long structures, in the concentration regime of 63-70 wt % FS. A lamellar (Lα) lyotropic liquid-crystalline (LLC) phase forms at higher concentration, between 70 and 84 wt %.