133 research outputs found
Fracture of high-density polyethylene used for bleach bottles
No full textHigh-density polyethylene (HDPE) can be blow-molded and used for the production of bottles for aggressive products. These products can interact both chemically and physically with the polymer constituting these containers, leading to a decrease in the performance of the material and undermining the structural integrity of the component.
A fracture mechanics approach was adopted to evaluate the Environmental Stress Cracking Resistance (ESCR) of two HDPE commercial grades used for bleach containers; two different solutions, with and without sodium hypochlorite (the main ingredient of commercial bleach solutions), were considered as aggressive environments. Size effects were studied using different test configurations and loading histories in air. The correlation between the stress intensity factor and the initiation time was found. A clear effect of the aggressive solutions on the fracture resistance of the two HDPEs was observed, irrespective of the presence of sodium hypochlorite; the effect therefore has to be ascribed to other bleach components
Spectroscopic Evidence for the Contribution of Holes to the Bleach of Cd-Chalcogenide Quantum Dots
No full textIn transient absorption (TA) measurements on Cd-chalcogenide quantum dots (QDs), the presence of a band-edge (BE) bleach signal is commonly attributed entirely to conduction-band electrons in the 1S(e) state, neglecting contributions from BE holes. While this has been the accepted view for more than 20 years, and has often been used to distinguish electron and hole kinetics, the reason for the absence of a hole contribution to the BE-bleach has remained unclear. Here, we show with three independent experiments that holes do in fact have a significant impact on the BE-bleach of well-passivated Cd-chalcogenide QD samples. Transient absorption experiments on high photoluminescence quantum yield CdSe/CdS/ZnS core-shell-shell QDs clearly show an increase of the band-edge bleach as holes cool down to the band edge. The relative contribution of electron-to-hole bleach is 2:1, as predicted by theory. The same measurements on core-only CdSe QDs with a lower quantum yield do not show a contribution of holes to the band-edge bleach. We assign the lack of hole bleach to the presence of ultrafast hole trapping in samples with insufficient passivation of the QD surface. In addition, we show measurements of optical gain in core-shell-shell QD solutions, providing clear evidence of a significant hole contribution to the BE transient absorption signal. Finally, we present spectroelectrochemical measurements on CdTe QDs films, showing the presence of a BE-bleach for both electron and hole injections. The presence of a contribution of holes to the bleach in passivated Cd-chalcogenides QDs bears important implications for quantitative studies on optical gain as well as for TA determinations of carrier dynamics.ChemE/Opto-electronic Material
Community Action Research in Ireland: Improving Educational Outcomes Through Collaboration in the Dublin Docklands
No full textThis chapter examines how, over the past seven years, a process of community action research has given direction, meaning, and motivation to the Early Learning Initiative (ELI) in the National College of Ireland. The author describes the ELI, a community-based initiative aimed at addressing educational disadvantage and children and young people in the Docklands of Dublin, Ireland. Operating as a partnership between several groups and institution, including parents, public health nurses, early years’ services, schools, funders, and community organizations, ELI has developed innovative programs that are improving the literacy and numeracy skills of children and young people in the Docklands. Over 4,000 children, parents, and professionals actively engage in ELI’s programs each year
Space Plants for Astronaut Consumption
No full textGrowing plants in space will be an essential part of sustaining astronauts during long-range missions. During the summer of 2017, three female NASA interns, have been engaged in research relevant to food production in space, and will present their projects to an all female program known as Girls in STEM camp. Ayla Grandpre, a senior from Rocky Mountain College, has performed data mining and analysis of crop growth results gathered through Fairchild Botanical Gardens program, Growing Beyond Earth. Ninety plants were downselected to three for testing in controlled environment chambers at KSC. Ayla has also managed an experiment testing a modified hydroponics known as PONDS, to grow mizuna mustard greens and red robin cherry tomatoes. Emma Boehm, a senior from the University of Minnesota, has investigated methods to sterilize seeds and analyzed the most common microbial communities on seed surfaces. She has tested a bleach fuming method and an ethanol treatment. Emma has also tested Tokyo bekana Chinese cabbage seeds from four commercial seed vendors to identity differences in germination and growth variability. Lastly, Payton Barnwell, a junior from Florida Polytechnic University has shown that light recipes provided by LEDs can alter the growth and nutrition of 'Outredgeous' lettuce, Chinese cabbage, and Mizuna. The results of her light quality experiments will provide light recipe recommendations for space crops that grown in the Advanced Plant Habitat currently aboard the International Space Station
Portoro, the black and gold Italian “marble”
No full textPortoro is one of the most famous Italian black limestones due to its characteristic golden-yellow veins on a black background. It was used since Roman times, mainly in the city of Luni. Since the Middle Ages, its use is widespread in Genoa, and from the XVII century, it became one of the most common stones in religious buildings throughout Italy. At the end of the XIX century, its use has spread abroad, particularly in Europe and USA. It was extracted in several quarrying areas located near La Spezia, but at present, only five quarries are active. This stone, exposed to weathering, tends to bleach losing the appearance of its golden streaks that determine its aesthetic appeal. This research deals with the petrographic and chemical characterization of the Portoro macchia larga variety as well as the study of its chromatic alteration in order to define guidelines for the most suitable use of this stone and for restoration works
Periparturient and early lactation performance and metabolism of replacement Holstein-Friesian heifers out-wintered on fodder beet or perennial ryegrass compared with winter housing
No full textThe effect of winter feeding system on the periparturient performance and early milk production and metabolism of pregnant Holstein‐Friesian dairy heifers destined for a high‐output, total mixed ration (TMR)‐based system was examined. Forty‐eight, 23 ± 0.4‐month‐old, in‐calf Holstein‐Friesian heifers were assigned to one of three treatments: out‐wintered on perennial ryegrass and grass silage (G), out‐wintered on fodder beet and grass silage (F) or housed and fed grass silage and concentrate (H). The study commenced in November 2013, with heifers on treatment for 91 days, housed from 6 weeks prior to parturition and fed a dry cow TMR. Postpartum performance and metabolism were monitored for 12 weeks. Prepartum, average daily gain was lower in heifers receiving G at 0.95 kg d−1 cow−1 than F or H (1.24 and 1.11 kg d−1 cow−1 respectively). Body condition score of heifers that received G was also lower compared with treatments F or H both pre‐ and postpartum. Prepartum, plasma β‐hydroxybutyrate concentrations were lowest in animals receiving treatment H, highest in F and intermediate in G, but did not differ between treatment postpartum. Milk yield averaged 30.7 kg d−1 cow−1 and was not affected by treatment, but milk fat content was lowest in animals that received F (35.4, 37.1 and 37.9 g/kg for F, G and H respectively). The results indicate that out‐wintering in‐calf dairy heifers on fodder beet or perennial ryegrass is a viable alternative to winter housing in high‐output TMR‐based milk production systems in a temperate region
Appropriate dairy calf feeding from birth to weaning: “It’s an investment for the future”
No full textDairy calves must be fed appropriately to meet their nutritional needs, supporting optimal growth and development to achieve the recommended target age at first calving (AFC) of 24 months. Traditional restricted milk feeding practices suppress growth, contribute to negative welfare states and may result in malnutrition and immunosuppression. Despite more recent recommendations to increase milk allowances for pre-weaned calves, restricted feeding remains a common practice. This study explored the rationales behind the calf feeding protocols used by dairy farmers in England. Forty qualitative interviews (26 farmers, 14 advisors) were conducted between May 2016 and June 2017, transcribed in full, then coded into themes. Results indicate that a variety of calf feeding regimes are used on farms, largely determined by farmers’ attitudes regarding ease of management and the wellbeing of calves. Advisors were concerned about widespread underfeeding of calves, which may be partially due to insufficiently clear recommendations for calf milk replacer (CMR) feeding rates. There was also evidence of uncertainty regarding best practices for weaning calves. Collaboration between academic research and industry is essential to establish a consensus on calf feeding standards which support physiological function, facilitate weaning, support growth targets and ensure calf health and welfare is protected
Assessment of the potential for microbial contamination of antarctic terrestrial habitats resulting from human activities (previously ASAC 870)
No full textProgress Code: completedStatement:
Values provided in temporal and spatial coverage are approximate only.This project was a continuation of ASAC project 870 (ASAC_870).<br/><br/>The aim of the project is to assess the possible routes for the carriage of microorganisms by humans to Antarctic soil habitats. Such pathways include footwear, vehicle treads and washings of root vegetables. These have been examined and measures have already been implemented to minimise further risk from these sources. A further aim was to determine the likelihood of foreign microorganisms successfully competing with indigenous terrestrial antarctic microorganisms; this has proved more difficult to ascertain under simulated antarctic conditions. Work is continuing on this aspect.<br/><br/>The danger posed by microbial contaminants on expeditioners' boots to antarctic wildlife habitats has been assessed, with the finding that bacterial spores would survive current walk-through disinfection procedures using 2% Virkon or 3%-chlorine bleach, although coliforms would not. The problem of spore-survival in sanitizing solutions is exacerbated by residual clay in boot treads. It is recommended that boots be scrubbed clean of residual soil or clay before entering antarctic waters, and again as necessary between geographically isolated areas within Antarctica. Soaking for four hours in 2.0% Virkon or for 11 minutes in 3% chlorine bleach is needed for a 3-log reduction in Bacillus spore numbers.<br/><br/>Results:<br/>The following Decimal Reduction Times (DRTs) were obtained:<br/>B. subtilis, 80 and 84 minutes in 2% Virkon , 3.6 min in 3%-chlorine bleach.<br/>B. polymyxa, 32 minutes in 2% Virkon , 3.0 min in 3%-chlorine bleach.<br/>Vegetative cells of E. coli died very rapidly in both Virkon and 3%-chlorine bleach, with DRTs being less than 18 seconds, the limit of detection using the described method
Dramatic water usage reduction with valuables recovery in pulp mill:Removal of non-process elements
No full textPulp industry is one of the most water consuming industry. Sustainable water use and the use of raw materials arises as a threshold issue when moving toward sustainable and material efficient pulp production. Closure of water circuits can significantly reduce the total water consumption of mill.This study examines the closure of the water cycles in the bleaching plant of kraft pulp mill with application of tertiary treatment methods to remove non-process elements from the acid bleach filtrate. When closing the water cycle, harmful non-process elements (NPEs) can accumulate in the process as the possible purge points are eliminated. Especially earth metals can cause uncontrolled precipitation on the process equipment, causing process disturbances. Calcium is one of the non-process elements most harmful to the process, causing precipitates in bleaching. Additionally, some NPEs like cadmium can cause problems in wastewater treatment plant especially in sludge utilization.The NPEs studied in the thesis were cadmium, calcium, and phosphorus. The selective separation of those from the process waters of acid bleaching stage to separate fractions was examined. Precipitation, filtration, adsorption, and ion exchange were chosen as the separation techniques to be examined. The overall and selective separation efficiency of the desired substances was examined by single separation techniques and by combinations of different separation techniques.Results proved the overall separation efficiency of nanofiltration to be highest among other tested treatment methods for all elements measured. Permeate received can be re-used in the process whilst concentrate can be treated further. Sulphide and phosphate precipitation yielded promising results for the selective removal of cadmium from the acid bleach filtrate. Carbonate precipitation was found efficient but non-viable option in the separation of calcium due to the high chemical consumption
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