86 research outputs found
Utilizing Benign Oxidants for Selective Aerobic Oxidations Using Heterogenized Platinum Nanoparticle Catalysts
No full textCopyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. By using platinum nanoparticle catalysts that are generated in situ by extrusion from a porous copper chlorophosphate framework, the role of oxidants in the selective oxidation of benzyl alcohol to benzaldehyde was evaluated, with a view to establishing structure-property relationships. With a detailed study of the kinetic properties of the oxidation reaction, it has been determined that the aerobic oxidation pathways progress with lower levels of product selectivity and higher activation energies (72.4-1) than the peroxide-based ones (23.6-1); affording valuable insights in the design of solid catalysts for selective oxidation reactions. Furthermore, through the use of X-ray absorption spectroscopy, the effect of calcination temperature on the degree of extrusion and its influence on nanoparticle formation have been evaluated, leading to the establishment of structure-activity correlations between the observed activation energies and the proportion of nanoparticle species generated. Tuned cats.: Well-defined platinum nanoparticles are generated in situ by anion extrusion within porous framework architectures (see figure). In these catalysts the local structural environment of the active site is controlled by the calcination conditions, and thus industrially significant, sustainable catalytic oxidation reactions are possible with tert-butyl hydroperoxide (TBHP) or oxygen.link_to_subscribed_fulltex
Probing the origin of in situ generated nanoparticles as sustainable oxidation catalysts
No full textA novel method for the in situ generation of catalytically active small metal nanoparticles, by anion extrusion on a parent porous copper chloropyrophosphate framework, has been developed to generate gold, platinum and palladium nanoparticles for sustainable catalytic oxidations using molecular oxygen as the oxidant. Transmission electron microscopy coupled with detailed structural and physico-chemical characterisation, in combination with in-depth kinetic analysis have afforded profound insights into the nature of the active site for facilitating structure–property correlations
Utilisation of gold nanoparticles on amine-functionalised UiO-66 (NH2-UiO-66) nanocrystals for selective tandem catalytic reactions
No full textColloidal deposition of gold nanoparticles (Au NPs) onto NH2-UiO-66 nanocrystals has been demonstrated with the resulting hybrid catalyst proving robust and versatile for one-pot, heterogeneous conversions involving the selective oxidation of primary alcohols in tandem with Knoevenagel condensation reactions. Within these systems, structure-property correlations have been established to confirm that the active sites for the oxidation and condensation reactions are intrinsically correlated to the Au NPs and pendant amine groups respectively
Elucidating structure-property relationships in the design of metal nanoparticle catalysts for the activation of molecular oxygen
No full text© 2015 American Chemical Society. A novel synthetic strategy for the design of metal nanoparticles by extrusion of anionic chloride precursors from a porous copper chlorophosphate framework has been devised for the sustainable aerobic oxidation of vanillyl alcohol (4-hydroxy-3-methoxybenzyl alcohol) to vanillin (4-hydroxy-3-methoxybenzaldehyde) using a one-step, base-free method. The precise nature of the Au, Pt, and Pd species has been elucidated for the as-synthesized and thermally activated analogues, which exhibit fascinating catalytic properties when subjected to diverse activation environments. By employing a combination of structural and spectroscopic characterization tools, it has been shown that analogous heat treatments have differing effects on extrusion of a particular metal species. The most active catalysts in this series of materials were the extruded Pt nanoparticles that were generated by reduction in H2, which exhibit enhanced catalytic behavior, when compared to its Au or Pd counterparts, for industrially significant, aerobic oxidation reactions.link_to_subscribed_fulltex
Design of Highly Selective Platinum Nanoparticle Catalysts for the Aerobic Oxidation of KA-Oil using Continuous-Flow Chemistry.
No full textHighly active and selective aerobic oxidation of KA-oil to cyclohexanone (precursor for adipic acid and ɛ-caprolactam) has been achieved in high yields using continuous-flow chemistry by utilizing uncapped noble-metal (Au, Pt & Pd) nanoparticle catalysts. These are prepared using a one-step in situ methodology, within three-dimensional porous molecular architectures, to afford robust heterogeneous catalysts. Detailed spectroscopic characterization of the nature of the active sites at the molecular level, coupled with aberration-corrected scanning transmission electron microscopy, reveals that the synthetic methodology and associated activation procedures play a vital role in regulating the morphology, shape and size of the metal nanoparticles. These active centers have a profound influence on the activation of molecular oxygen for selective catalytic oxidations
Reasoning Consistently about Inconsistency
No full textPatching et al. and Hinde et al. in their work on
truth-space mass assignments, presented a semantic unification
function and a semantic separation function for mass assignment
logic that dealt with inconsistency. This paper takes these
two functions and while preserving the outside inconsistencies
shows how inconsistency can be reasoned about in a consistent
manner. This means that inconsistency that arises outside the
system need not enter the system, but needs to be represented
within the system, and can therefore be extracted appropriately
as output from the system to emerge as inconsistency on the
outside. The internal reasoning system need therefore only
concern itself with belief in truth, falsity and uncertainty
A model to assess organisational information privacy maturity against the Protection of Personal Information Act
No full textIncludes bibliographical references.Reports on information security breaches have risen dramatically over the past five years with 2014 accounting for some high-profile breaches including Goldman Sachs, Boeing, AT&T, EBay, AOL, American Express and Apple to name a few. One report estimates that 868,045,823 records have been breached from 4,347 data breaches made public since 2005 (Privacy Rights Clearing House, 2013). The theft of laptops, loss of unencrypted USB drives, hackers infiltrating servers, and staff deliberately accessing client’s personal information are all regularly reported (Park, 2014; Privacy Rights Clearing House, 2013) . With the rise of data breaches in the Information Age, the South African government enacted the long awaited Protection of Personal Information (PoPI) Bill at the end of 2013. While South Africa has lagged behind other countries in adopting privacy legislation (the European Union issued their Data Protection Directive in 1995), South African legislators have had the opportunity to draft a privacy Act that draws on the most effective elements from other legislation around the world. Although PoPI has been enacted, a commencement date has still to be decided upon by the Presidency. On PoPI’s commencement date organisations will have an additional year to comply with its requirements, before which they should: review the eight conditions for the lawful processing of personal information set out in Chapter three of the Act; understand the type of personal information they process ; review staff training on mobile technologies and limit access to personal information; ensure laptops and other mobile devices have passwords and are preferably encrypted; look at the physical security of the premises where personal data is store d or processed; and, assess any service providers who process in formation on their behalf. With the demands PoPI places on organisations this research aims to develop a prescriptive model providing organisations with the ability to measure their information privacy maturity based on “generally accepted information security practices and procedure s” ( Protection of Personal Information Act, No.4 of 2013 , sec. 19(3)) . Using a design science research methodology, the development process provides three distinct design cycles: 1) conceptual foundation 2) legal evaluation and 3) organisational evaluation. The end result is the development of a privacy maturity model that allows organisations to measure their current information privacy maturity against the PoPI Act. This research contributes to the knowledge of how PoPI impacts on South African organisations, and in turn, how organisations are able to evaluate their current information privacy maturity in respect of the PoPI Act. The examination and use of global best practices and standards as the foundation for the model, and the integration with the PoPI Act, provides for the development of a unique yet standards-based privacy model aiming to provide practical benefit to South African organisations
March Mammal Madness and the power of narrative in science outreach
No full textFull author list omitted for brevity. For the full list of authors, see article.March Mammal Madness is a science outreach project that, over the course of several weeks in March, reaches hundreds of thousands of people in the United States every year. We combine four approaches to science outreach - gamification, social media platforms, community event(s), and creative products - to run a simulated tournament in which 64 animals compete to become the tournament champion. While the encounters between the animals are hypothetical, the outcomes rely on empirical evidence from the scientific literature. Players select their favored combatants beforehand, and during the tournament scientists translate the academic literature into gripping "play-by-play" narration on social media. To date ~1100 scholarly works, covering almost 400 taxa, have been transformed into science stories. March Mammal Madness is most typically used by high-school educators teaching life sciences, and we estimate that our materials reached ~1% of high-school students in the United States in 2019. Here we document the intentional design, public engagement, and magnitude of reach of the project. We further explain how human psychological and cognitive adaptations for shared experiences, social learning, narrative, and imagery contribute to the widespread use of March Mammal Madness
Changes in Physical Performance during British Army Junior Entry, British Army Standard Entry, and Royal Air Force Basic Training
No full textIntroduction: To quantify changes in physical performance in men and women during British Army Junior Entry (Army-JE), Standard Entry (Army-SE), and Royal Air Force (RAF) Basic Training (BT). Design: Prospective longitudinal study. Methods: 381 participants [(339 men, 42 women) n=141 Army-JE; n=132 Army-SE; n=108 RAF] completed a 2-km Run, Medicine Ball Throw (MBT) and isometric Mid-Thigh Pull (MTP), pre- and post-BT. To examine changes in pre- to post- BT physical test performance, for each course, paired students t-tests, and Wilcoxon tests were applied to normally and non-normally distributed data respectively; with effect sizes reported as Cohen’s D and with rank biserial correlations, respectively. A one-way between-subjects ANOVA (or Welch ANOVA for non-normally distributed data) compared performance between quartiles based on test performance pre-BT. Where the main tests statistic, p value and effect sizes identified likely effect of quartile, post-hoc comparisons were made using Games-Howell tests with Tukey’s p value. Data are presented as mean ± standard deviation, statistical significance set at p<0.05. Results: During BT, 2-km run time improved by 13±46 (-2.1±8.1%), 30±64 (-4.8±12.3%), and 24±27 s (-4.5±5.1%) for Army-JE, Army-SE, and RAF, respectively (all p<0.005). MBT distance increased by 0.27±0.28 m (6.8±7.0%) for Army-JE (p<0.001) and 0.07±0.46 m (2.3±10.9%) for Army-SE (p=0.040), but decreased by 0.08±0.27 m (-1.4±6.0%) for RAF (p=0.002). MTP force increased by 80±281 N (10.8±27.6%) for Army-JE (p<0.001) and did not change for Army-SE (-36±295 N, -0.7±20.6%, p=0.144) or RAF (-9±208 N, 1.0±17.0, p=0.603). For all tests and cohorts, participants in the lowest quartile of pre-BT performance scores demonstrated greater improvements, compared with participants in the highest quartile (except Army-JE MBT; ∆% change similar between all quartiles). Conclusions: Changes in physical performance were observed for the three fitness tests following the different BT courses, but recruits with the lowest strength and aerobic fitness experienced greatest improvements
The Impact of Covid-19 Outbreak on the Tourism Needs of the Algerian Population
No full textThis research aims to understand the vision and the reaction of the population towards tourism and holidays during this period of the COVID-19 pandemic. It also investigates the tourist needs of the Algerian population after the closure of international borders. Methods: The data were collected using a mixture of quantitative and qualitative methods through a questionnaire applied to 203 people in different regions of Algeria (a North African country) from 1 June to 13 July 2020. Results: The needs of Algerian tourists were characterized by a great need for leisure to relieve psychological stress caused by COVID-19 (M = 25.33) among the study sample (p < 0.05). The results also show an average need to rationalize the costs of tourist services (M = 5.26) according to the respondents (p < 0.01). This is in addition to the great need (M = 7.75) among respondents (p < 0.05) of the awareness that the tourism sector can contribute to the economic recovery in Algeria after the confinement period. About 75.86% of respondents requested the cleanliness of tourist sites, while 69.95% recommended improving safety because of the size of tourist sites in the Algerian territory as well as measures related to social distancing. The results show that 53.69% of respondents preferred the month of August to go on vacation, 29.06% chose the month of September, and 17.25% would prefer the months of October, November, and December since they expected a reduction in the risks of the COVID-19 pandemic. Conclusions: The COVID-19 pandemic has affected the tourism needs of the Algerian population, which has become increasingly aware of the consequences of the pandemic in relation to their health and in relation to the country’s economy. These results can help the authorities of the tourism sector to better understand and identify the tourism needs of this population in the current period and after the COVID-19 pandemic
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