Practical applications of small-angle neutron scattering.

Recent improvements in beam-line accessibility and technology have led to small-angle neutron scattering (SANS) becoming more frequently applied to materials problems. SANS has been used to study the assembly, dispersion, alignment and mixing of nanoscale condensed matter, as well as to characterise the internal structure of organic thin films, porous structures and inclusions within steel. Using time-resolved SANS, growth mechanisms in materials systems and soft matter phase transitions can also be explored. This review is intended for newcomers to SANS as well as experts. Therefore, the basic knowledge required for its use is first summarised. After this introduction, various examples are given of the types of soft and hard matter that have been studied by SANS. The information that can be extracted from the data is highlighted, alongside the methods used to obtain it. In addition to presenting the findings, explanations are provided on how the SANS measurements were optimised, such as the use of contrast variation to highlight specific parts of a structure. Emphasis is placed on the use of complementary techniques to improve data quality (e.g. using other scattering methods) and the accuracy of data analysis (e.g. using microscopy to separately determine shape and size). This is done with a view to providing guidance on how best to design and analyse future SANS measurements on materials not listed below

Super Duplex Stainless Steels: Influence of Copper & Tungsten on the Passivity and Corrosion Resistance

This thesis has investigated the corrosion behaviour of three Super Duplex Stainless Steelgrades, FERR (UNS 32250), SAF (UNS S32750) and ZER (UNS S32760), with focus on theinfluence of copper (Cu) and tungsten (W) content on pitting and crevice corrosion. In addition,the influence of surface roughness and deaeration of the environment was explored. Theexperiments involved potentiostatic polarisation techniques and microscopy to quantify thefrequency, area and depth of dissolution observed. Two mass loss models, Faraday’s Law & PitGeometry, were also implemented to further quantity the corrosion seen.The samples were exposed to a 3.5% w/v solution and heated from 65 °C to 85 °C at aramp rate of 40 °C/hour. The Critical Pitting Temperatures (CPT) showed a minimal 4 °Cdifference between the highest, of additional W content, ZER and the lowest, of low Cu content,SAF. FERR, which has increased Cu content, displayed substantial pit frequency, aligning withthe high recorded currents. The presence of metastable pitting was observed, contributing to pitrepassivation and lower pitting corrosion in SAF and ZER. Despite expectations, additional Win ZER did not produce significantly improved results. The mass loss calculations correlatedwell with potentiostatic results although several factors like lacy pits and pit shape variabilityimpacted accuracy.Samples were used from previous research that were ground to a smoother surface finish andexposed to a 3.5% w/v solution. A deaerated environment using a nitrogen inlet wascreated, and the samples heated from 65 °C to 85 °C at a ramp rate of 30 °C/hour. FERR andZER demonstrated improved performance in the deaerated conditions, attributed to smootherfinish reducing pit initiation sites, and decreased cathodic reactions in oxygen depletedenvironments. SAF exhibited contrasting results with increased dissolution observed.The samples were exposed to 3.5% w/v solution at temperatures of 85 °C, 75 °C and 65°C, utilising an o-ring to change the preferred method of corrosion from pitting to crevice. At 85°C, all grades exhibited substantial dissolution due to surpassing Critical Crevice Temperatures(CCT). FERR and ZER showed similar crevice depths, implying no significant impact of Cuor W additions. At 75 °C, a reduction in current and crevice depths were seen, with somesamples showing incomplete crevice formation around the circumference. At 65 °C, corrosionrates declined significantly, with some areas showing no crevice formation. FERR and ZERagain showed similar performance. SAF exhibited stable performance over the temperaturerange with potential for a broad range of temperature applications.Overall, this research highlighted insights into the complex relationship between composition,temperature and other factors of corrosion behaviour. While Cu additions did not show asignificant impact in aerated conditions, it showed much improvement in deaeratedenvironments. The addition of W had a more influential role in aerated conditions, althoughboth Cu and W additions performed similarly under the crevice corrosion mechanism. Thelower alloyed SAF seemed to have irregular behaviour across all experiments apart from crevicecorrosion. Additionally, a smoother surface finish and absence of oxygen became a crucialfactor for influencing corrosion rate

Porous 'Ouzo-effect' silica-ceria composite colloids and their application to aluminium corrosion protection.

By exploiting spontaneous emulsification to prepare porous SiO(2) particles, we report the formation of porous CeO(2)@SiO(2) hybrid colloids and their incorporation into a silica-zirconia coating to improve the corrosion protection of aluminium

A flexible one-pot route to metal/metal oxide nanocomposites

We report a one-pot route to Au/CeO2 nanocomposites. A readily-available biopolymer, sodium alginate, is exploited for controlled formation and stabilisation of gold nanoparticles followed by in situ growth of a sponge-like network of CeO2 nanoparticles. The flexible nature of this method as a general route to mixed metal/metal oxide nanocomposites is also demonstrated

Increased physical fitness is associated with higher executive functioning in people with dementia

Physical fitness (PF) has been associated with improved cognition in older age, but less is known about its effects on different cognitive domains in individuals diagnosed with dementia. We explored the associations between PF and cognitive performance in 40 healthy elderly and 30 individuals with dementia. Participants completed a battery of standardized cognitive tests (Mini-Mental State Exam, Verbal Fluency, Prospective and Retrospective Memory Questionnaire, Clock Drawing, and California Verbal Learning Test) and were classified into high versus low levels of PF based on their score on the Physical Fitness Questionnaire. Analyses took into account age, gender, education, occupation, head injury, Internet use, brain training, and past levels of exercise and revealed overall benefits of PF, in particular for the people with dementia. Discriminant analysis showed high accuracy of reclassification, with most errors being due to the misclassification of dementia cases as healthy when they had high PF. The first discriminant function accounted for 83% of the variance. Using individual estimates of this function, which reflected global cognitive performance, confirmed the beneficial role of PF in dementia, even when taking into account age, past level of exercise, and the number of years since the dementia diagnosis. Finally, univariate analyses confirmed the differential sensitivity of the cognitive tests, with MMSE and clock drawing showing reliable interaction effects. This work shows that PF is associated with a reduced level of cognitive deterioration expected with dementia, especially in executive functioning and provides empirical support for the cognitive benefits of interventions promoting PF for individuals with dementia

Alkylated-C-60 based soft materials: regulation of self-assembly and optoelectronic properties by chain branching

Derivatization of fullerene (C60) with branched aliphatic chains softens C60-based materials and enables the formation of thermotropic liquid crystals and room temperature nonvolatile liquids. This work demonstrates that by carefully tuning parameters such as type, number and substituent position of the branched chains, liquid crystalline C60 materials with mesophase temperatures suited for photovoltaic cell fabrication and room temperature nonvolatile liquid fullerenes with tunable viscosity can be obtained. In particular, compound 1, with branched chains, exhibits a smectic liquid crystalline phase extending from 84 °C to room temperature. Analysis of bulk heterojunction (BHJ) organic solar cells with a ca. 100 nm active layer of compound 1 and poly(3-hexylthiophene) (P3HT) as an electron acceptor and an electron donor, respectively, reveals an improved performance (power conversion efficiency, PCE: 1.6 ± 0.1%) in comparison with another compound, 10 (PCE: 0.5 ± 0.1%). The latter, in contrast to 1, carries linear aliphatic chains and thus forms a highly ordered solid lamellar phase at room temperature. The solar cell performance of 1 blended with P3HT approaches that of PCBM/P3HT for the same active layer thickness. This indicates that C60 derivatives bearing branched tails are a promising class of electron acceptors in soft (flexible) photovoltaic devices

The synthesis of triphosphine ligands and their macrocycles

A new synthesis is described for the production of a single monodentate aromatic phosphine ligand for coordination to a metal centre. 2-fluorophenyl phosphine was synthesised in good yield and has been coordinated to a variety of metal centres. There seems to be no inhibiting factors preventing the phosphine coordinating to any metal centres in a facial manner. Further investigation will be required to see if the 2-fluorophenyl phosphine can be cyclised with a suitable base before the macrocycle can be liberated from the metal centre. Linear triphosphine ligands have previously been reported to coordinate to metal centres as tridentate chelating ligands. Cyclisation to produce the macrocycle has been achieved through cyclocondensation reactions utilising high dilution, high temperature techniques. Reported here is a new synthetic route to a linear triphosphine by coupling benzyl phosphine with two equivalents of vinyl phosphonate before it’s reduction using lithium aluminium hydride. An attempted cyclisation of the triphosphine utilising calcium iodide as the metal centre in a template synthesis is described