A systematic approach to the formulation of anti-onychomycotic nail patches

Nail patches have a potential role as drug carriers for the topical treatment of nail diseases such as onychomycosis, a common condition. O ur aim was therefore to develop a systematic and novel appr oach to the formulat ion of a simple drug -in-adhesive ungual patch. Twelve pressure -sensitive adhesives (PSAs), four backing membranes, two release liners and three drugs were screened for pharmaceutical and mechanical properties . From this initial screeni ng, two PSAs, two drugs, one backing membrane and one release liner were selected for further investigation. Patches were prepared by solvent -casting and characterised. The patches had good uniformity of thickness and of drug content, and showed minimal drug crystallisation during six month s of storage. Meanwhile, the d rug stability in the patch upon storage and patch adhesion to the nail was influenced by the nature of the drug, the PSA and the backing membrane . The reported methodology paves the way for a systematic formulation of ungual nail patches to add to the armamentarium of nail medicines . Further , from this work, the best patch formulation has been identified

Modeling the effect of rate and geometry on peeling and tack of pressure-sensitive adhesives

A model is developed for predicting separation along interfaces of pressure sensitive adhesives. Many authors have used the cohesive zone approach to solve such problems but the parameter calibration of such models remains uncertain. This study reports a novel method for determining such parameters. In addition, it provides crucial evidence for the suitability of the cohesive zone model approach in modelling interface fractures. Peel tests were performed at various rates using specimens which consisted of a polyester backing membrane supporting an acrylic pressure-sensitive adhesive (PSA) adhered to a polyethylene substrate. Interfacial separation of the PSA from the polyethylene substrate was observed. Finite element (FE) peeling simulations were conducted which modeled the backing-membrane as an elasto-plastic power-law material, the adhesive as a viscoelastic material and the interfacial properties with a cohesive zone model (CZM). The material properties of the backing membrane and the pressure-sensitive adhesive were measured from tensile and stress relaxation experiments. The rate-dependent CZM parameters were measured directly from poker-chip probe-tack tests which were performed at pull-off speeds which corresponded to the rates employed for the peel tests. The effect of the PSA thickness and test rate on both tack and peel was investigated experimentally, as well as modeled numerically. Good agreement was found between the experimentally measured and numerically predicted peel forces for different peel angles, speeds and PSA thicknesses. In addition, it was proven that the rate dependence observed in the peel and probe-tack data was dominated by the rate dependence of the interface properties, i.e. the time dependence of the two CZM parameters of maximum stress and fracture energy, rather than the time-dependent bulk viscoelasticity of the PSA peel arm

Contamination of Sachet Water in Nigeria: Assessment and Health Impact

Adequate supply of fresh and clean drinking water is a basic need for all human beings. Water consumers are frequently unaware of the potential health risks associated with exposure to water borne contaminants which have often led to diseases like diarrhoea, cholera, dysentery, typhoid fever, legionnaire’s disease and parasitic diseases. The inadequacy of pipe borne water-supply in Nigeria is a growing problem; as a result people resort to buying water from vendors, and sachet or bottled water became a major source of drinking water. Although, portable and affordable, the problems of its purity and other health concerns have begun to manifest. Sachet water have been reported to contain bacteria such as Bacillus sp., Pseudomonas sp., Klebsiella sp., Streptococcus sp., and oocysts of Cryptosporidia sp. Apart from environmental contaminants, improper storage and handling by vendors also poses a serious threat to the health of the ignorant consumers. This paper tends to review the quality of these ‘pure water’; its physical examination, microbial assessments, its impacts on health, and the various strategies adopted by the concerned authorities to regulate this thriving industry

Determination of a critical stress and distance criterion for crack propagation in cutting models of cheese

A critical stress at a critical distance crack propagation criterion is a good way to model the fracture in cheese. This physical criterion states that the crack-tip node debonds when the stress at a specified distance ahead of the crack tip on the assumed crack path reaches a critical value. Although this criterion is already used in other research domains, no consistent information exists on how the critical stress and distance should be determined. A repeatable method for the determination of this criterion which combines experimental and numerical single edge notched bending tests was acquired. This criterion was validated with wire cutting experiments of cheese. The experimental and numerical results showed the same trend with a clear wire indentation and steady state cutting phase. The determination of a critical stress and distance criterion as proposed in this research is a good approach to model fracture and cutting of cheese

Creating Physical 3D Stereolithograph Models of Brain and Skull

The human brain and skull are three dimensional (3D) anatomical structures with complex surfaces. However, medical images are often two dimensional (2D) and provide incomplete visualization of structural morphology. To overcome this loss in dimension, we developed and validated a freely available, semi-automated pathway to build 3D virtual reality (VR) and hand-held, stereolithograph models. To evaluate whether surface visualization in 3D was more informative than in 2D, undergraduate students (n = 50) used the Gillespie scale to rate 3D VR and physical models of both a living patient-volunteer's brain and the skull of Phineas Gage, a historically famous railroad worker whose misfortune with a projectile tamping iron provided the first evidence of a structure-function relationship in brain. Using our processing pathway, we successfully fabricated human brain and skull replicas and validated that the stereolithograph model preserved the scale of the VR model. Based on the Gillespie ratings, students indicated that the biological utility and quality of visual information at the surface of VR and stereolithograph models were greater than the 2D images from which they were derived. The method we developed is useful to create VR and stereolithograph 3D models from medical images and can be used to model hard or soft tissue in living or preserved specimens. Compared to 2D images, VR and stereolithograph models provide an extra dimension that enhances both the quality of visual information and utility of surface visualization in neuroscience and medicine