Polyol-mediated zinc oxide nanoparticles using the refluxing method as an efficient photocatalytic and antimicrobial agent

Nanomaterials have attracted more curiosity recently because of their wide-ranging application in environmental remediation and electronic devices. The current study focuses on zinc oxide nanoparticles’ (ZnO NPs) simple production, characterization, and applications in several fields, including medicinal and photocatalytic degradation of dyes. The non-aqueous-based reflux method is helpful for ZnO NP synthesis; the procedure involves refluxing zinc acetate dihydrate precursor in ethylene glycol for 3 hours in the absence of sodium acetate, in which the refluxing rate and the cooling rate are optimized to get the desired phase, and the unique morphology of polyol-mediated ZnO NPs; it has been achieved using the capping agent TBAB (tetra-butyl ammonium bromide) and precursor zinc acetate dihydrate. UV–Vis, FTIR, XRD, and FESEM structurally characterized polyol-mediated ZnO-NPs. The results show that the material is pure and broadly aggregated into spherical nanoparticles with an average particle size of 18.09 nm. According to XRD analysis, heat annealing made the crystallites more prominent and favored a monocrystalline state. These results and the low cost of making polyol-mediated ZnO NPs demonstrate photocatalytic and antimicrobial properties

Effects of fractional time derivatives in predator-prey models

This thesis is concerned with the effects of fractional derivatives in predator-prey like systems, including models of plant water interaction. In Chapter 3, a fractional order predator-prey model is introduced, and we show how fractional derivative order can change the system from monostable to bistable. The observable domains of attraction of the two stable points will also be considered, in particular how they change as the fractional order is changed. In Chapter 4, we will generalise the predator-prey model studied in Chapter 3 by considering different fractional orders for each species. This system is referred to as an incommensurate system. We will explain how the different fractional orders affect the stability of this model. Then, in order to see if this change in stability is a more general result, we will consider a plant-herbivore incommensurate system and study the stability of this system. We will also find an approximate analytical solution for the characteristic equation of the incommensurate system when the two fractional orders α and β are similar and both close to the critical value of the fractional order of the commensurate system.;In this case, we are able to map out the stable and unstable boundary as a functionof both parameters. We will compare the analytical and numerical solutions in these two incommensurate systems. In Chapter 5, we consider two different modelsof the interaction between surface water, soil water and plants. The first is similar to the model of Dagbovie and Sherratt, without spatial derivatives. We study the steady states of this model and observe the effect of adding the fractional order on the system. In the second model the soil water equation is replaced with the more realistic the Richards equation. In this model, we will also study the steady state and dynamic behaviour in the integer model and then consider the incommensurate fractional system. In this case, we see that a fractional order can affect the transient behaviour of the system.This thesis is concerned with the effects of fractional derivatives in predator-prey like systems, including models of plant water interaction. In Chapter 3, a fractional order predator-prey model is introduced, and we show how fractional derivative order can change the system from monostable to bistable. The observable domains of attraction of the two stable points will also be considered, in particular how they change as the fractional order is changed. In Chapter 4, we will generalise the predator-prey model studied in Chapter 3 by considering different fractional orders for each species. This system is referred to as an incommensurate system. We will explain how the different fractional orders affect the stability of this model. Then, in order to see if this change in stability is a more general result, we will consider a plant-herbivore incommensurate system and study the stability of this system. We will also find an approximate analytical solution for the characteristic equation of the incommensurate system when the two fractional orders α and β are similar and both close to the critical value of the fractional order of the commensurate system.;In this case, we are able to map out the stable and unstable boundary as a functionof both parameters. We will compare the analytical and numerical solutions in these two incommensurate systems. In Chapter 5, we consider two different modelsof the interaction between surface water, soil water and plants. The first is similar to the model of Dagbovie and Sherratt, without spatial derivatives. We study the steady states of this model and observe the effect of adding the fractional order on the system. In the second model the soil water equation is replaced with the more realistic the Richards equation. In this model, we will also study the steady state and dynamic behaviour in the integer model and then consider the incommensurate fractional system. In this case, we see that a fractional order can affect the transient behaviour of the system

Sterile versus nonsterile clean dressings

BACKGROUND: Many patients cannot afford sterile dressings. In St John, New Brunswick, clean dressings have been used instead of sterile dressings for years, with no apparent ill effects. No previous studies have compared the sterility and cost of clean versus sterile dressing materials. OBJECTIVES: The goals of the present study were to answer the following questions: how much more sterile are sterile dressings than clean dressings; and how much does this extra sterility cost? METHODS: Sterility and cost of sterile gauze, panty liners, sanitary napkins, diapers and Coban tape (3M, USA) were compared. Samples, 2 cm × 2 cm in size, were cut out of each material under aseptic conditions, and delivered to the microbiology laboratory in sterile urine containers. The samples were then cultured and organisms were identified using conventional means. RESULTS: The cost for one month, using one 20 cm × 5 cm wound dressing daily, was calculated and compared with panty liners ($2.43), sanitary napkins ($5.55), diapers ($9.39) and Coban tape ($0.66), which were much cheaper than sterile dressings ($16.50). How sterile were the dressings? None of the 20 sanitary napkins grew bacteria, one of the 20 panty liners grew bacteria (coagulase-negative Staphylococcus), two of 20 sterile dressings grew bacteria (one coagulase-negative Staphylococcus and one nonhemolytic Streptococcus), 15 of 20 diapers grew bacteria (all bacillus) and two of five Coban rolls grew bacteria (one bacillus and one coagulase-negative Staphylococcus). CONCLUSION: The panty liners, sanitary napkins and Coban tape studied were cheaper than, and had a comparible sterility with, the sterile gauze examined

SARS-CoV-2 vaccination modelling for safe surgery to save lives: data from an international prospective cohort study

Background: Preoperative SARS-CoV-2 vaccination could support safer elective surgery. Vaccine numbers are limited so this study aimed to inform their prioritization by modelling. Methods: The primary outcome was the number needed to vaccinate (NNV) to prevent one COVID-19-related death in 1 year. NNVs were based on postoperative SARS-CoV-2 rates and mortality in an international cohort study (surgical patients), and community SARS-CoV-2 incidence and case fatality data (general population). NNV estimates were stratified by age (18-49, 50-69, 70 or more years) and type of surgery. Best- and worst-case scenarios were used to describe uncertainty. Results: NNVs were more favourable in surgical patients than the general population. The most favourable NNVs were in patients aged 70 years or more needing cancer surgery (351; best case 196, worst case 816) or non-cancer surgery (733; best case 407, worst case 1664). Both exceeded the NNV in the general population (1840; best case 1196, worst case 3066). NNVs for surgical patients remained favourable at a range of SARS-CoV-2 incidence rates in sensitivity analysis modelling. Globally, prioritizing preoperative vaccination of patients needing elective surgery ahead of the general population could prevent an additional 58 687 (best case 115 007, worst case 20 177) COVID-19-related deaths in 1 year. Conclusion: As global roll out of SARS-CoV-2 vaccination proceeds, patients needing elective surgery should be prioritized ahead of the general population