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The role of protein hydrophobicity in thionin-phospholipid interactions : A comparison of α1 and α2-purothionin adsorbed anionic phospholipid monolayers

The plant defence proteins α1- and α2-purothionin (Pth) are type 1 thionins from common wheat (Triticum aestivum). These highly homologous proteins possess characteristics common amongst antimicrobial peptides and proteins, that is, cationic charge, amphiphilicity and hydrophobicity. Both α1- and α2-Pth possess the same net charge, but differ in relative hydrophobicity as determined by C18 reverse

Formation of shear thinning gels from partially oxidised cellulose nanofibrils

Partially C(6) oxidised, dispersed cellulose nanofibres form shear thinning gels in the presence of moderate amounts of simple salts or surfactants providing a novel method to structure aqueous formulations, which may be of use in a substantial number of applications where it is desirable to enhance the viscosity of formulated materials using components from a renewable, sustainable source.

Preparation dependent stability of pure silica MCM-41

The degradation of pure silica MCM-41 materials prepared under various synthesis conditions has been investigated. Materials from preparations titrated with acid during synthesis not only show improved long range ordering of the pore system but also greater stability. This effect is greatest in unheated preparations.

Formation of mesophase surfactant-templated silica thin films from acidic solutions

The formation of mesophase silica-surfactant thin films at the air/solution interface has been studied in situ using off-specular X-ray reflectivity, Brewster angle microscopy and small angle scattering. Results for cetyltrimethylammonium bromide-templated films suggest that the formation mechanism is strongly dependent on the silica:surfactant ratio, and this is confirmed by studies on the subpha

Hydrothermal core-shell carbon nanoparticle films : Thinning the shell leads to dramatic pH response

Carbon nanoparticles with phenylsulfonate negative surface functionality (Emperor 2000, Cabot Corp.) are coated with positive chitosan followed by hydrothermal carbonization to give highly pH-responsive core-shell nanocarbon composite materials. With optimised core-shell ratio (resulting in an average shell thickness of ca. 4 nm, estimated from SANS data) modified electrodes exhibit highly pH-sens

Soap and sand : Construction tools for nanotechnology

Nanotechnology is the science of making and using very small structures. As the scales of the constructions become smaller, the existing methods of making these structures - lithography, etching and micromoulding - although constantly improving, will reach physical limits. To overcome the limitations and create smaller, designed and ordered structures, a so-called 'bottom-up' approach must be used

Preparation and characterisation of chemisorbents based on heteropolyacids supported on synthetic mesoporous carbons and silica

The preparation of chemisorbents based on tungsto- and molybdophosphoric acids supported on two types of synthetic mesoporous carbons and two types of mesoporous silica is described. Strong solid acids with good accessibility to acid sites may potentially be effective adsorbents for the removal of basic molecular impurities, such as amines, from ultrapure manufacturing environments. Prepared mater

The effect of hydrogen on the morphology of n-type silicon electrodes under electrochemical conditions

We study the electrochemical roughening of a silicon electrode surface during the hydrogen evolution reaction in a fluoride electrolyte using neutron reflection. We demonstrate that as the roughening process modifies the morphology of the silicon surface we can follow the changes by observing the changes in the shape of the total reflection feature. We assume that the change in the morphology of t

Formation of surfactant-silica mesophase films at a silica interface

Neutron reflectometry has been used to study the development of mesoporous silicated films at a hydrophilic silicon-solution interface. We find the time for film formation was altered in a manner similar to that seen at the air-liquid interface as the silica source-to-surfactant ratio was altered. Interestingly for films grown at the silica-liquid interface in a cell with no air space only one gro

Electrochemically active mercury nanodroplets trapped in a carbon nanoparticle - chitosan matrix

A thin composite film of carbon nanoparticles (ca. 8 nm diameter) and chitosan biopolymer (poly-D-glucosamine, from chitin, 75-85% deacetylated) was prepared by evaporation from aqueous dispersion onto glassy carbon electrode surfaces. The amine groups in the chitosan biopolymer were used to effectively bind Hg(II) ions from an aqueous pH 5 KCl solution. During redox cycling voltammetric responses

The influence of mercury contact angle, surface tension, and retraction mechanism on the interpretation of mercury porosimetry data

The use of a semi-empirical alternative to the standard Washburn equation for the interpretation of raw mercury porosimetry data has been advocated. The alternative expression takes account of variations in both mercury contact angle and surface tension with pore size, for both advancing and retreating mercury meniscii. The semi-empirical equation presented was ultimately derived from electron mic

Structural studies on surfactant-templated silica films growtn at the air/water interface

In situ characterisation of a growing surfactant-templated silica film has been carried out by X-ray reflectivity, diffuse X-ray scattering from the surface. Brewster angle microscopy and surface pressure measurements. The results indicate an unexpected film growth mechanism where layered structures form in solution and diffuse to the interface after some critical induction period.

Humidity and temperature effects on CTAB-templated mesophase silicate films at the air-liquid interface

Off-specular X-ray reflectivity measurements were carried out to follow the in situ development of surfactant-templated silica thin films at the air-water interface under conditions of controlled relative humidity and temperature, using an enclosed sample cell designed for this purpose. The results suggest a strong dependence of formation time and growth mechanism on ambient conditions. Thin films

Microwave-electrochemical formation of colloidal zinc oxide at fluorine doped tin oxide electrodes

Colloidal ZnO is obtained during microwave-enhanced electrochemical deposition experiments from an aqueous solution containing 0.1 M Zn(NO 3)2 and 0.02 M H2O2 via repetitive negative going potential cycles from 0.3 to -0.8 V vs. SCE. The effects of temperature and temperature gradients on ZnO electro-formation at fluorine doped tin oxide (FTO) electrodes are investigated with both a conventional t

Self-assembled films formed at the air - Water interface from CTAB/SDS mixtures with water-soluble polymers

We have investigated the spontaneous self-assembly of solid, mesostructured films that form at the air-solution interface on solutions containing a neutral water-soluble polymer and catanionic surfactant mixtures of hexadecyl-trimethylammonium bromide (CTAB) and sodium dodecylsulphate (SDS). The formation processes and structures were probed using neutron reflectivity, X-ray reflectivity, off-spec

Control of mesostructure in self-assembled polymer/surfactant films by rational micelle design

Micron-thick hydrogel films with ordered 3D mesostructures form spontaneously at the interface of polyelectrolyte-surfactant solutions. Here we demonstrate that by rationally designing the micelle shapes it is possible to predict and so tailor the nanostructure formed within surfactant-polyelectrolyte films. Using quaternary ammonium surfactants with a range of packing parameters, we demonstrate t

Using nano-cast model porous media and integrated gas sorption to improve fundamental understanding and data interpretation in mercury porosimetry

The mechanisms of entrapment, and the nanoscopic spatial distribution, of the residual mercury within nano-cast and amorphous porous media (pore sizes ∼1-100 nm) following high-pressure penetration have been studied. It has been shown that, even at the nanoscale, one of the same two principle mechanisms that have been observed previously in mercury porosimetry experiments on macroscopic glass pore

Nanocasting of novel, designer-structured catalyst supports

Highly structured catalyst support pellets have been produced that possess multiple, but regiospecific and well-defined, pore geometries. Mesoporous silica pellets with controlled pore sizes have been synthesised using one type of pore template for the pellet core zone, whilst using a different type of template for the surrounding shell region. These materials offer the potential of adding precise