Tuning of the characteristics of Au nanoparticles produced by solid target laser ablation into water by changing the irradiation parameters.

We report the production of Au nanoparticles with different average sizes and size distributions, by laser ablation of a solid Au target into pure deionized water. Tuning laser parameters such as pulse duration, energy, and wavelength is possible to tune the size and the size distributions of the produced nanoparticles into the liquid. We demonstrate the possibility of production of highly monodispersed colloidal solutions, in which the average nanoparticle size ranges from 3 to 10 nm, using laser pulses of ns duration. Laser ablation using fs laser pulses can also produce very small nanoparticles, although a small population of bigger nanoparticles is always present. Low and high-resolution transmission electron microscopy (TEM), in combination with UV-Vis spectroscopy have been employed for the characterization of our samples

The Effect of Irradiation Wavelength on the Quality of CdS Nanocrystals Formed Directly into PMMA Matrix

UV laser irradiation of PMMA films containing Cd thiolate precursors results in the spatially selective formation of CdS crystalline nanoparticles in the host matrix. Here we investigate the effect of the irradiation wavelength on the quality of the formed nanocrystals. Fluorescence topography and XPS studies reveal that the polymer matrix contributes to the trap states formation on the surface of the nanocrystals. When the latter are formed upon irradiation at 266 nm, they exhibit broad emission spectra, ascribed to the high degree of photodegradation of the polymer. In contrast, the irradiation at 355 nm does not chemically modify the matrix, resulting in the formation of CdS nanocrystals with narrow emission, i.e. high emission quality. This is further confirmed by fluorescence lifetime topography studies giving a mean fluorescence nanocrystal lifetime as short as 200 ps at room temperature. Thus, the optimized combination of irradiation wavelength with polymer matrix gives nanocomposite materials inco..

Electrical response from nanocomposite PDMS-Ag NPs generated by in situ laser ablation in solution.

Laser ablation technique is employed in order to generate polydimethylsiloxane (PDMS)/Ag NPs in situ, starting from a silver target in a solution of PDMS prepolymer and toluene. The produced surfactant-free nanoparticles are characterized by high resolution transmission electron microscopy (HRTEM) and scanning TEM-high angle annular dark field (STEM-HAADF) imaging modes, showing the majority of them to be of the order of 4 nm in diameter with a small percentage of larger Ag-AgCl multidomain NPs, embedded into a PDMS matrix. Low concentrations of carbon onion-like nanoparticles or larger fibers are also formed in the toluene-PDMS prepolymer solution. In accordance with this, UV-vis spectra shows no peak from silver NPs; their small size and their coverage by the PDMS matrix suppresses the signal of surface plasmon absorption. Inductively coupled plasma measurements reveal that the concentration of silver in the polymer is characteristically low, ∼0.001% by weight. The electrical properties of the PDMS nanocomposite films are modified, with current versus voltage (I-V) measurements showing a low current of up to a few tenths of a pA at 5 V. The surface resistivity of the films is found to be up to ∼1010 Ω/sq. Under pressure (e.g. stress) applied by a dynamic mechanical analyzer (DMA), the I-V measurements demonstrate the current decreasing during the elastic deformation, and increasing during the plastic deformation

Water-repellent cellulose fiber networks with multifunctional properties.

We demonstrate a simple but highly efficient technique to introduce multifunctional properties to cellulose fiber networks by wetting them with ethyl-cyanoacrylate monomer solutions containing various suspended organic submicrometer particles or inorganic nanoparticles. Solutions can be applied on cellulosic surfaces by simple solution casting techniques or by dip coating, both being suitable for large area applications. Immediately after solvent evaporation, ethyl-cyanoacrylate starts cross-linking around cellulose fibers under ambient conditions because of naturally occurring surface hydroxyl groups and adsorbed moisture, encapsulating them with a hydrophobic polymer shell. Furthermore, by dispersing various functional particles in the monomer solutions, hydrophobic ethyl-cyanoacrylate nanocomposites with desired functionalities can be formed around the cellulose fibers. To exhibit the versatility of the method, cellulose sheets were functionalized with different ethyl-cyanoacrylate nanocomposite shells..

Behavioural and Developmental Interventions for Autism Spectrum Disorder: A Clinical Systematic Review

Background: Much controversy exists regarding the clinical efficacy of behavioural and developmental interventions for improving the core symptoms of autism spectrum disorders (ASD). We conducted a systematic review to summarize the evidence on the effectiveness of behavioural and developmental interventions for ASD. Methods and Findings: Comprehensive searches were conducted in 22 electronic databases through May 2007. Further information was obtained through hand searching journals, searching reference lists, databases of theses and dissertations, and contacting experts in the field. Experimental and observational analytic studies were included if they were written in English and reported the efficacy of any behavioural or developmental intervention for individuals with ASD. Two independent reviewers made the final study selection, extracted data, and reached consensus on study quality. Results were summarized descriptively and, where possible, meta-analyses of the study results were conducted. One-hundred-and-one studies at predominantly high risk of bias that reported inconsistent results across various interventions were included in the review. Meta-analyses of three controlled clinical trials showed that Lovaas treatment was superior to special education on measures of adaptive behaviour, communication and interaction, comprehensive language, daily living skills, expressive language, overall intellectual functioning and socialization. High-intensity Lovaas was superior to low-intensity Lovaas on measures of intellectual functioning in two retrospective cohort studies. Pooling the results of two randomized controlle

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Fate of pharmaceuticals in the environment - A review-

The occurrence of pharmaceuticals in environment originating from human consumption has received increased scientific attention during the last decades due to concerns regarding their combined environmental effects in aquatic and terrestrial environments, in flora and biota and by extent in human health. In this review, I summarized the existing knowledge on the entire life cycle of pharmaceutical substances, from their exposure (sources) and fate to their effects on the natural environment. Since the negative effects of several drugs along with the environmental damage they entail are now known, it can be suggested that pharmaceutical companies make greener pharmaceutical products to reduce these effects to the terrestrial and aquatic environment. The present review could provide suggestions to improve the pharmaceutical environmental management globally, such as methodologies for monitoring systems, that need to be put in place for consistent data collection. Another area of research that is important is the release of pharmaceutical compounds in manufacturing plants as well as from landfill effluent. Finally, one more area with need for further research is green chemistry which could reduce or even eliminate the potential hazards of pharmaceutical compounds that enter the environment, irrespective to the source of entry

Fate of pharmaceuticals in aquatic environments in Northern Sweden

The occurrence of pharmaceuticals in aquatic environments originating from human consumption has received increased scientific attention during the last decades due to concerns regarding their combined environmental effects. This concerns stress the need of studies quantifying dissipation rates of pharmaceutical in aquatic ecosystems. The aims of this study were: i) to assess the degradation rates of trimethoprim (TPR), diphenhydramine (DPH), diclofenac (DCL), oxazepam (OXZ) and hydroxyzine (HDZ) in laboratory incubations, and ii) to compare laboratory assessment of dissipation rates with previously measured in situ half-lives of these drugs in a pond ecosystem. I hypothesized that the dissipation of these five drugs dissolved, in laboratory incubations, is affected by common environmental parameters such as temperature, UV-light, organic solutes and presences of sediments. In line with my hypothesis, all substances were affected by my treatments. Here, main parameters affecting the dissipation of the drugs were UV light and to a lesser temperature (i.e. through microbial degradation). All drugs were found to be affected by sediment sorption, especially HDZ where 95 % of the applied pharmaceutical was adsorbed. Laboratory estimate with highest environmental relevance (low TOC and 3 °C water temperature or low TOC, sediments and UV light) seemed to predict field estimates fairly well for all of the drugs beside OXZ and DCL. Given the strong adsorption for sediments seen in the laboratory incubations, it seems likely that the mismatch between laboratory inferred half-lives and the in situ half-lives for OXZ was likely caused by sediment exchange processes releasing drugs initially adsorbed to the sediments into water column over time

Image and text juxtapositions in conceptual art in Britain 1967-1972

EThOS - Electronic Theses Online ServiceGBUnited Kingdo