Surfactant Adsorption at Liquid–Solid Interfaces

Surfactant adsorption to the liquid–solid interface is of great importance to many industrial and consumer processes; from detergency to crop spraying and drilling for oil, the understanding of how these molecules behave is crucial to their design and further efficiency improvement. This thesis describes how a Raman spectrometer for use in total-internal reflection (TIR)-Raman spectroscopy was built and commissioned to provide a new, open bench system. The prime aim was to improve on the time resolution of our existing commercial spectrometer (to <1 s) and allow for easy modification. TIR-Raman spectroscopy allows us to be surface-selective by only measuring the Raman spectrum from very close to the interface, where the evanescent field excites molecules attached to, or very close to the surface. As this field decays exponentially with distance, only a small region at the interface is probed (≈100 nm). Using an in-line mixer we were able to record adsorption and desorption isotherms on the surfaces. This technique utilised a continuously stirred tank to vary continually the concentration of solution entering the cell, hence a whole continuous range of concentrations (limited only by the time resolution) could be studied. The validity of our in-line mixer is tested with solutions of the Raman-active molecules acetonitrile, methanol, and sucrose. The adsorption to silica of various anionic surfactants (sodium dodecyl sulphate (SDS) and sodium dodecylbenzenesulfonate (C12LAS)), nonionic surfactants (polyethylene oxide alkyl ethers (CnEms)) and cationic surfactants (single and double chained tertiary ammonium bromides (CnTABs) and DHDAB) were investigated. Varying mixtures of nonionic and anionic surfactant adsorption on hydrophobic silica are covered briefly. With the individual surfactants, the investigation started with a plain (acid-washed) silica hemisphere, then moved to various coatings applied to silica, using the same TIR-Raman technique. The additional model substrates studied were hydrophobic silica (treated with hexamethyldisilazane), zeolite, kaolinite, polyester and (although largely unsuccessful) haematite

Penetration of Surfactant Solutions into Capillaries

This investigation studies the processes by which water and surfactant solutions penetrate macroscopic, horizontal, hydrophilic glass capillaries. Additional investigations were conducted on some capillaries that are made hydrophobic by being silanised. A laser is shone along the capillary to illuminate the advancing meniscus, so the meniscus is seen as a dot of light, which is detected by a high-speed camera. An investigation on the effect of the presence and type of surfactant aims to reveal the processes by which penetration occurs. Dissipation in the wedge was investigated as a source of deviation from Lucas-Washburn behaviour. Three theoretical models were compared to the experimental data: (I) The Lucas-Washburn model, (II) A “Young” model and (III) Overflowing cylinder model. All these models are shown to be unable to account for the observed penetration rates. The wedge of liquid near the three-phase contact line is considered as a possible additional dissipative mechanism. Penetration of surfactant solutions into capillaries filled with oil is investigated. Due to the viscosity matching effect of this technique, viscous dissipation is constant

Study protocol: imaging brain development in the Childhood to Adolescence Transition Study (iCATS)

BackgroundPuberty is a critical developmental phase in physical, reproductive and socio-emotional maturation that is associated with the period of peak onset for psychopathology. Puberty also drives significant changes in brain development and function. Research to date has focused on gonadarche, driven by the hypothalamic-pituitary-gonadal axis, and yet increasing evidence suggests that the earlier pubertal stage of adrenarche, driven by the hypothalamic-pituitary-adrenal axis, may play a critical role in both brain development and increased risk for disorder. We have established a unique cohort of children who differ in their exposure to adrenarcheal hormones. This presents a unique opportunity to examine the influence of adrenarcheal timing on brain structural and functional development, and subsequent health outcomes. The primary objective of the study is to explore the hypothesis that patterns of structural and functional brain development will mediate the relationship between adrenarcheal timing and indices of affect, self-regulation, and mental health symptoms collected across time (and therefore years of development).Methods/DesignChildren were recruited based upon earlier or later timing of adrenarche, from a larger cohort, with 128 children (68 female; M age 9.51 years) and one of their parents taking part. Children completed brain MRI structural and functional sequences, provided saliva samples for adrenarcheal hormones and immune biomarkers, hair for long-term cortisol levels, and completed questionnaires, anthropometric measures and an IQ test. Parents completed questionnaires reporting on child behaviour, development, health, traumatic events, and parental report of family environment and parenting style.DiscussionThis study, by examining the neurobiological and behavioural consequences of relatively early and late exposure to adrenarche, has the potential to significantly impact our understanding of pubertal risk processes.<br /

Quality indicators for Palliative Day Services: A modified Delphi study

BACKGROUND: The goal of Palliative Day Services is to provide holistic care that contributes to the quality of life of people with life threatening-illness and their families. Quality indicators provide a means by which to describe, monitor and evaluate the quality of Palliative Day Services provision, and act as a starting point for quality improvement. However, currently, there are no published quality indicators for Palliative Day Services. AIM: To develop and provide the first set of quality indicators that describe and evaluate the quality of Palliative Day Services. DESIGN AND SETTING: A modified Delphi technique was used to combine best available research evidence derived from a systematic scoping review with multi-disciplinary expert appraisal of the appropriateness and feasibility of candidate indicators. The resulting indicators were compiled into ‘toolkit’, and tested in five UK Palliative Day Service settings. RESULTS: A panel of experts independently reviewed evidence summaries for 182 candidate indicators and provided ratings on appropriateness, followed by a panel discussion and further independent ratings of appropriateness, feasibility, and necessity. This exercise resulted in the identification of 30 indicators which were used in practice testing. The final indicator set comprised 7 structural indicators, 21 process indicators, and 2 outcome indicators. CONCLUSIONS: The indicators fulfil a previously unmet need among Palliative Day Service providers by delivering an appropriate and feasible means to assess, review, and communicate the quality of care, and to identify areas for quality improvement

British signals intelligence and the 1916 Easter Rising in Ireland

Historians for decades have placed Room 40, the First World War British naval signals intelligence organization, at the centre of narratives about the British anticipation of and response to the Easter Rising in Ireland in 1916. A series of crucial decrypts of telegrams between the German embassy in Washington and Berlin, it has been believed, provided significant advance intelligence about the Rising before it took place. This article upends previous accounts by demonstrating that Room 40 possessed far less advance knowledge about the Rising than has been believed, with most of the supposedly key decrypts not being generated until months after the Rising had taken place

Nurse-led group consultation intervention reduces depressive symptoms in men with localised prostate cancer: a cluster randomised controlled trial

BACKGROUND: Radiotherapy for localised prostate cancer has many known and distressing side effects. The efficacy of group interventions for reducing psychological morbidity is lacking. This study investigated the relative benefits of a group nurse-led intervention on psychological morbidity, unmet needs, treatment-related concerns and prostate cancer-specific quality of life in men receiving curative intent radiotherapy for prostate cancer. METHODS: This phase III, two-arm cluster randomised controlled trial included 331 men (consent rate: 72&nbsp;%; attrition: 5&nbsp;%) randomised to the intervention (n&thinsp;=&thinsp;166) or usual care (n&thinsp;=&thinsp;165). The intervention comprised four group and one individual consultation all delivered by specialist uro-oncology nurses. Primary outcomes were anxious and depressive symptoms as assessed by the Hospital Anxiety and Depression Scale. Unmet needs were assessed with the Supportive Care Needs Survey-SF34 Revised, treatment-related concerns with the Cancer Treatment Scale and quality of life with the Expanded Prostate Cancer Index -26. Assessments occurred before, at the end of and 6 months post-radiotherapy. Primary outcome analysis was by intention-to-treat and performed by fitting a linear mixed model to each outcome separately using all observed data. RESULTS: Mixed models analysis indicated that group consultations had a significant beneficial effect on one of two primary endpoints, depressive symptoms (p = 0.009), and one of twelve secondary endpoints, procedural concerns related to cancer treatment (p = 0.049). Group consultations did not have a significant beneficial effect on generalised anxiety, unmet needs and prostate cancer-specific quality of life. CONCLUSIONS: Compared with individual consultations offered as part of usual care, the intervention provides a means of delivering patient education and is associated with modest reductions in depressive symptoms and procedural concerns. Future work should seek to confirm the clinical feasibility and cost-effectiveness of group interventions

Invaders in hot water: a simple decontamination method to prevent the accidental spread of aquatic invasive non-native species.

Watersports equipment can act as a vector for the introduction and spread of invasive non native species (INNS) in freshwater environments. To support advice given to recreational water users under the UK Government’s Check Clean Dry biosecurity campaign and ensure its effectiveness at killing a range of aquatic INNS, we conducted a survival experiment on seven INNS which pose a high risk to UK freshwaters. The efficacy of exposure to hot water (45 °C, 15 min) was tested as a method by which waters users could ‘clean’ their equipment and was compared to drying and a control group (no treatment). Hot water had caused 99 % mortality across all species 1 h after treatment and was more effective than drying at all time points (1 h: χ2 = 117.24, p < 0.001; 1 day χ2 = 95.68, p < 0.001; 8 days χ2 = 12.16, p < 0.001 and 16 days χ2 = 7.58, p < 0.001). Drying caused significantly higher mortality than the control (no action) from day 4 (χ2 = 8.49, p < 0.01) onwards. In the absence of hot water or drying, 6/7 of these species survived for 16 days, highlighting the importance of good biosecurity practice to reduce the risk of accidental spread. In an additional experiment the minimum lethal temperature and exposure time in hot water to cause 100 % mortality in American signal crayfish (Pacifastacus leniusculus), was determined to be 5 min at 40 °C. Hot water provides a simple, rapid and effective method to clean equipment. We recommend that it is advocated in future biosecurity awareness campaigns

Urbanisation affects ecosystem functioning more than structure in tropical streams

Urbanisation poses a clear threat to tropical freshwater streams, yet fundamental knowledge gaps hinder our ability to effectively conserve stream biodiversity and preserve ecosystem functioning. Here, we studied the impact of urbanisation on structural and functional ecosystem responses in low-order streams in Singapore, a tropical city with a mosaic landscape of protected natural forests, managed buffer zones (between forest and open-country habitats), and built-up urban areas. We quantified an urbanisation gradient based on landscape, in-stream, and riparian conditions, and found an association between urbanisation and pollution-tolerant macroinvertebrates (e.g. freshwater snail and worm species) in litter bags. We also found greater macroinvertebrate abundance (mean individuals bag−1; forest: 30.3, buffer: 70.1, urban: 109.0) and richness (mean taxa bag−1; forest: 4.53, buffer: 4.75, urban: 7.50) in urban streams, but similar diversity across habitats. Higher levels of primary productivity (measured from algal accrual on ceramic tiles) and microbial decomposition (measured from litter-mass loss in mesh bags) at urban sites indicate rapid microbial activity at higher light, temperature, and nutrient levels. We found that urbanisation affected function 32% more than structure in the studied tropical streams, likely driven by greater algal growth in urban streams. These changes in ecological processes (i.e. ecosystem functioning) possibly lead to a loss of ecosystem services, which would negatively affect ecology, society, and economy. Our results point to possible management strategies (e.g. increasing vegetation density through buffer park creation) to reduce the impacts of urbanisation, restore vital ecosystem functions in tropical streams, and create habitat niches for native species