Maintaining the Integrity Over Wear Time of a Hydrocolloid-based Ostomy Adhesive Whilst Maintaining Skin Barrier Function

In this extensive body of work, a thorough exploration delves into hydrocolloid based adhesives, with a focus on addressing challenges faced by stoma patients, particularly the susceptibility of ostomy adhesives to breakdown upon exposure to liquids. Stoma patients, compelled to wear pouching systems continuously, encounter issues like the compromise of skin barrier integrity, leading to medical adhesive-related skin injuries. The primary objective of this thesis is to reinforce the structural integrity of ostomy adhesives while preserving the skin barrier during pouching system use, an aspect often overlooked in current literature due to the hydrophilic nature of hydrocolloid based adhesives. The study introduces novel aims, examining the potential link between handedness and the preferred direction of adhesive removal, and its impact on peristomal skin complications as well as a novel skin capacitive imagery stitching technique. Another goal involves developing hierarchical structures on adhesive surfaces to enhance integrity, initial tack, and minimize skin contact for optimal skin health. The introduction provides a detailed breakdown of hydrocolloid-based ostomy adhesives, stoma anatomy, and the purpose of pouching systems. A comprehensive literature review, utilizing the PICO approach, encompasses stoma anatomy, physiology, indications for stoma surgery, and methods for assessing skin health. The review explores various methodologies to improve the durability of hydrocolloid-based adhesives, incorporating hydrodynamics, crosslinking, and layering systems. The potential influence of handedness on adhesive removal techniques is examined, considering its impact on peristomal skin complications. Results reveal the consistent performance of Welland Medical Ltd.'s hydrocolloid based adhesive but highlight the need for improved integrity over wear time. Strategies include modifying sodium-carboxymethylcellulose degree of substitution and increasing pectin degree of esterification, resulting in enhanced fluid handling capabilities and reduced susceptibility to degradation. Residual testing indicates that residual particles on the skin can impair the barrier function, remedied by a silicone-based adhesive remover. Surveys show that a patient's dominant hand and following the skin's natural langer lines during adhesive removal may minimize skin trauma. The results also show that structured surface profiles on hydrocolloid-based adhesive surfaces impact the skin's functional barrier recovery time. The research goal of this project and its objectives have been reached, the approaches have been explained clearly and implementations have been assessed using experimental findings. This project's findings contribute to advancements in ostomy care by enhancing adhesive performance, understanding patient behaviour, and improving the overall user experience. It also facilitates the efficient detachment of the adhesive from the skin surface

The clinical and cellular basis of contact lens-related corneal infections

Microbial keratitis (MK) is the most visually devastating complication associated with contact lens wear. Pseudomonas aeruginosa (PA) is highly invasive in the corneal epithelium and is responsible for more than half of the reported cases of contact lens-related MK. To protect against Pseudomonas-mediated MK, the corneal epithelium has evolved overlapping defense mechanisms that function to protect the ocular surface from microbial invasion. Research has shown that contact lens wear disrupts these protective mechanisms through breakdown of normal homeostatic surface renewal as well as damaging the corneal surface, exposing underlying cell membrane receptors that bind and internalize PA through the formation of lipid rafts. Human clinical trials have shown that initial adherence of PA with resulting increased risk for microbial infection is mediated in part by contact lens oxygen transmissibility. Recently, chemical preserved multipurpose solutions (MPS) have been implicated in increasing PA adherence to corneal epithelial cells, in addition to inducing significant levels of toxic staining when used in conjunction with specific silicone hydrogel lenses. This review summarizes what is currently known about the relationship between contact lenses, the corneal epithelium, MPS, and infection

Scaling depth from shadow offset

When an object casts a shadow on a background surface, both the offset of the shadow and the blur of itspenumbra are potential cues to the distance betweenthe object and the background. However, the shadowoffset and blur are also affected by the direction andangular extent of the light source and these are oftenunknown. This means that the observer must makesome assumptions about the illumination, the expecteddistribution of depth, or the relation between offset anddepth in order to use shadows to make distancejudgments. Here, we measure human judgments ofperceived depth over a range of shadow offsets, blurs,and lighting directions to gain insight into this internalmodel.We find that distance judgments are relativelyunaffected by blur or light direction, whereas theshadow offset has a strong and linear effect. The dataare consistent with two models, a genericshadow-to-depth model and a Bayesian mode

Temporal Changes in Cd Sorption and Plant Bioavailability in Compost-Amended Soils

The application of Cd-contaminated phosphate fertiliser has enriched concentrations of this non-essential element in many agricultural soils. Consequently, concentrations of the metal in some agricultural products exceed the Maximum Limit in foods. Composts can reduce the transfer of Cd from soil to plants; however, it is unclear how long this beneficial effect endures. We aimed to determine temporal changes of phytoavailable Cd in two market garden soils (an Allophanic Orthic Granular Soil and a Recent Silt Loam). Soils were amended with either municipal green waste compost or sawdust and animal waste compost at a rate of 2.5% w/w under three incubation regimes: at 19 °C, at 30 °C, and at 30 °C with additional N added as urea at 0.6 g urea/kg soil added over 1 year. Each replicate was sampled after 1, 5, 9, 13, 21, 31, and 49 weeks, and phytoavailable Cd was estimated through 0.05 M Ca(NO3)2 extraction. Seed potato (Solanum tuberosum), ‘Nadine’ variety, was grown in the Pukekohe Allophanic Orthic Granular Soil, freshly amended with municipal compost and the same soil aged for one year. The concentration of Cd in all samples was analysed using an ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometer). The C concentration in the soil—compost mixtures decreased over the year, with the greatest decreases occurring in the soils incubated at 30 °C with added N. Unexpectedly, the concentration of Ca(NO3)2-extractable Cd in the compost-amended soils did not increase over time and in some cases even decreased. This was confirmed through a pot experiment, which showed the Cd concentration in potato was reduced by 50% in both the freshly amended soil and the amended soil aged for one year. Cadmium immobilisation in soils might be due to both the sorption of Cd by organic matter and the occlusion of sorbed Cd by oxy-hydroxides of iron and aluminium. Over 49 weeks, soluble Cd does not increase as organic matter oxidises. The application of municipal compost to soil will reduce both plant Cd solubility and plant Cd uptake for at least one year in the soils tested

Frontostriatal anatomical connections predict age- and difficulty-related differences in reinforcement learning

Contains fulltext : 167812.pdf (Publisher’s version ) (Closed access)Reinforcement learning (RL) is supported by a network of striatal and frontal cortical structures that are connected through white-matter fiber bundles. With age, the integrity of these white-matter connections declines. The role of structural frontostriatal connectivity in individual and age-related differences in RL is unclear, although local white-matter density and diffusivity have been linked to individual differences in RL. Here we show that frontostriatal tract counts in young human adults (aged 18-28), as assessed noninvasively with diffusion-weighted magnetic resonance imaging and probabilistic tractography, positively predicted individual differences in RL when learning was difficult (70% valid feedback). In older adults (aged 63-87), in contrast, learning under both easy (90% valid feedback) and difficult conditions was predicted by tract counts in the same frontostriatal network. Furthermore, network-level analyses showed a double dissociation between the task-relevant networks in young and older adults, suggesting that older adults relied on different frontostriatal networks than young adults to obtain the same task performance. These results highlight the importance of successful information integration across striatal and frontal regions during RL, especially with variable outcomes.12 p