Precipitation of nickel and cobalt sulphides using different reactor configurations

The nickel reduction process produces a stream containing unreacted dissolved nickel and cobalt. Removal of these metals to optimum levels is desired, however, the product should also be easy to handle and the process easy to incorporate into the current system. There are various precipitation agents that can be used to remove metals from solution, these being hydroxide, carbonates or sulphides. Sulphide precipitation has been gaining increased attention because of the advantages it holds above the other methods. These include: - attainment of high degree of metal removal over a broad pH range; - effective removal of metals such as As, eu and Hg even at low pH; - low retention time required in the reaction tank because of high reactivity; - feasibility of selective metal recovery There are various methods of introducing the sulphide into the system as well, with a soluble sulphide source most commonly used. The problem with this, and coupled to the high reactivity of the sulphide ion, is the creation of high local supersaturation. The supersaturation governs all precipitation and crystallisation processes in the way that it features in nucleation and growth rates. In crystallisation processes, the supersaturation can easily be controlled by thermal methods of evaporation or cooling. However, in precipitation, the creation of supersaturation is by a reaction, which commonly leads to high supersaturation. Thus, to obtain a product that has good filterability and settling ability, methods for controlling the supersaturation in precipitation reactions needs to be investigated

Step into the zone: career dancers, cultural work and intensity

No abstract available

Interplay between function and structure in complex networks

We show that abrupt structural transitions can arise in functionally optimal networks, driven by small changes in the level of transport congestion. Our results offer an explanation as to why so many diverse species of network structure arise in Nature (e.g. fungal systems) under essentially the same environmental conditions. Our findings are based on an exactly solvable model system which mimics a variety of biological and social networks. We then extend our analysis by introducing a novel renormalization scheme involving cost motifs, to describe analytically the average shortest path across multiple-ring-and-hub networks. As a consequence, we uncover a 'skin effect' whereby the structure of the inner multi-ring core can cease to play any role in terms of determining the average shortest path across the network.Comment: Expanded version of physics/0508228 with additional new result

The acute and chronic implications of the COVID-19 virus on the cardiovascular system in adults: A systematic review

Despite coronavirus disease 2019 (COVID-19) primarily being identified as a respiratory illness, some patients who seemingly recovered from initial infection, developed chronic multi-system complications such as cardiovascular (CV), pulmonary and neurological issues leading to multiple organ injuries. However, to date, there is a dearth of understanding of the acute and chronic implications of a COVID-19 infection on the CV system in adults. A systematic review of the literature was conducted according to PRISMA guidelines and prospectively registered via Prospero (ID: CRD42022360444). The MEDLINE Ovid, Cochrane Library and PubMed databases were searched from inception to August 2022. The search strategy keywords and MeSH terms used included: 1) COVID; 2) coronavirus; 3) long COVID; 4) cardiovascular; and 5) cardiovascular disease. Reference lists of all relevant systematic reviews identified were searched for additional studies. A total of 11,332 records were retrieved from database searches, of which 310 records were duplicates. A further 9887 were eliminated following screening of titles and abstracts. After full-text screening of 1135 articles, 9 manuscripts were included for review. The evidence of CV implications post-COVID-19 infection is clear, and this must be addressed with appropriate management strategies that recognise the acute and chronic nature of cardiac injury in COVID-19 patients. Efficacious management strategies will be needed to address long standing issues and morbidity

A role for consolidation in cross-modal category learning

The ability to categorize objects and events is a fundamental human skill that depends upon the representation of multimodal conceptual knowledge. This study investigated the acquisition and consolidation of categorical information that required participants to integrate information across visual and auditory dimensions. The impact of wake- and sleep-dependent consolidation were investigated using a paradigm in which training and testing were separated by a delay spanning either an evening of sleep or daytime wakefulness, with a paired-associate episodic memory task used as a measure of classic sleep-dependent consolidation. Participants displayed good evidence of category learning, but did not show any wake- or sleep-dependent changes in memory for category information immediately following the delay. This is in contrast to paired-associate learning, where a sleep-dependent benefit was observed in memory recall. To replicate real-world concept learning, in which knowledge is acquired across multiple distinct episodes, participants were given a second opportunity for category learning following the consolidation delay. Here we found an interaction between consolidation and learning; with greater improvements in category knowledge as a result of the second session learning for those participants who had a sleep filled delay. These results suggest a role for sleep in the consolidation of recently acquired categorical knowledge; however this benefit does not emerge as an immediate benefit in memory recall, but by enhancing the effectiveness of future learning. This study therefore provides insights into the processes responsible for the formation and development of conceptual representations

Synthesis of novel secosteroids

SIGLEAvailable from British Library Document Supply Centre- DSC:DX182390 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The historiography of the formation of the Union of South Africa

No abstract available. CopyrightDissertation (MHCS)--University of Pretoria, 2010.Historical and Heritage Studiesunrestricte

Innovation in High-End Food Service During COVID-19 Lockdowns

COVID-19 lockdown measures have forced hospitality operators to re-configure their dynamic capabilities through innovating operational practices and pivoting traditional business models. The high-end food service sector has undergone a particularly drastic shift towards a new normal. This qualitative study explores factors facilitating innovation at 16 high-end food service organizations in Finland and the UK through semi-structured expert interviews. Three key themes facilitating innovation during COVID-19 lockdowns are identified: 1) Combining high-tech and high-touch through new ways of producing and providing technology-driven service offerings, 2) Prosocial engagement, i.e. working together with multiple stakeholders to bring added value to all parties, not just the business, and 3) Reactivity, i.e. pushing the traditional boundaries of the sector through quick decision-making and constant iteration and refining of processes and procedures. Drawing our empirical findings together, innovation during COVID-19 lockdowns in high-end food service is conceptualized into three phases: React, Refine, and Reflect

Forests and Carbon: A Synthesis of Science, Management, and Policy for Carbon Sequestration in Forests

The goal of this volume is to provide guidance for land managers and policymakers seeking to understand the complex science and policy of forest carbon as it relates to tangible problems of forest management and the more abstract problems of addressing drivers of deforestation and negotiating policy frameworks for reducing CO2 emissions from forests. It is the culmination of three graduate seminars at the Yale School of Forestry & Environmental Studies focused on carbon sequestration in forest ecosystems and their role in addressing climate change

Predicted and observed impacts of COVID-19 lockdowns:Two Health Impact Assessments in Scotland and Wales

Health Impact Assessment is a key approach used internationally to identify positive or negative impacts of policies, plans and proposals on health and well-being. In 2020, HIAs were undertaken in Scotland and Wales to identify the potential health and well-being impacts of the 'stay at home' and physical distancing measures implemented at the start of the coronavirus disease (COVID-19) pandemic. There is sparse evidence evaluating whether the impacts predicted in HIAs occur following policy implementation. This paper evaluates the impacts anticipated in the COVID-19 HIAs against actual observed trends. The processes undertaken were compared and predicted impacts were tabulated by population groups and main determinants of health. Routine data and literature evidence were collated to compare predicted and observed impacts. Nearly all health impacts anticipated in both HIAs have occurred in the direction predicted. There have been significant adverse impacts through multiple direct and indirect pathways including loss of income, social isolation, disruption to education and services, and psychosocial effects. This research demonstrates the value of prediction in impact assessment and fills a gap in the literature by comparing the predicted impacts identified within the HIAs with observed trends. Post-COVID-19 recovery should centre health and well-being within future policies and decisions. Processes like HIA can support this as part of a 'health in all policies' approach to improve the health and well-being of populations