Influence of coal-particle size on emissions using the top-lit updraft ignition method

Despite the Government’s intervention of an intensive electrification program in South Africa, which has resulted in more than 87% of households being connected to the grid, a majority of low-income households still depend on solid fuel (coal and wood) as a primary source of energy, especially on the central Highveld. In informal settlements, combustion of coal is done in inefficient self-fabricated braziers, colloquially known as imbaulas. Emissions from domestic coal combustion result in elevated household and ambient air pollution levels that often exceed national air quality limits. Continued dependence on coal combustion exposes households to copious amounts of health-damaging pollutants. Despite the health significance of coal-burning emissions from informal braziers, there is still a dearth of emissions data from these devices. Consequently, evaluating the emission characteristics of these devices and to determine the resultant emission factors is needed. The effects of ignition methods and ventilation rates on particulate and gaseous emission from coal-burning braziers are reported in literature. However, to date there are no studies carried out to investigate the influence of the size of coal pieces on brazier emission performance. In this paper, we report on controlled combustion experiments carried out to investigate systematically, influences of coal particle size on gaseous and condensed matter (smoke) emissions from informal residential coal combustion braziers. Results presented are averages of three identical burn-cycles of duration three hours or fuel burn-out, whichever was the soonest

Applications of cytokinins in horticultural fruit crops : trends and future prospects

CITATION: Aremu, Adeyemi O. et al. 2020. Applications of cytokinins in horticultural fruit crops : trends and future prospects. Biomolecules, 10(9):1222, doi:10.3390/biom10091222.The original publication is available at: https://mdpi-res.comCytokinins (CKs) are a chemically diverse class of plant growth regulators, exhibiting wide-ranging actions on plant growth and development, hence their exploitation in agriculture for crop improvement and management. Their coordinated regulatory effects and cross-talk interactions with other phytohormones and signaling networks are highly sophisticated, eliciting and controlling varied biological processes at the cellular to organismal levels. In this review, we briefly introduce the mode of action and general molecular biological effects of naturally occurring CKs before highlighting the great variability in the response of fruit crops to CK-based innovations. We present a comprehensive compilation of research linked to the application of CKs in non-model crop species in different phases of fruit production and management. By doing so, it is clear that the effects of CKs on fruit set, development, maturation, and ripening are not necessarily generic, even for cultivars within the same species, illustrating the magnitude of yet unknown intricate biochemical and genetic mechanisms regulating these processes in different fruit crops. Current approaches using genomic-to-metabolomic analysis are providing new insights into the in planta mechanisms of CKs, pinpointing the underlying CK-derived actions that may serve as potential targets for improving crop-specific traits and the development of new solutions for the preharvest and postharvest management of fruit crops. Where information is available, CK molecular biology is discussed in the context of its present and future implications in the applications of CKs to fruits of horticultural significance.Publisher's versio

57Fe Mössbauer study of epitaxial TiN thin film grown on MgO(100) by magnetron sputtering

The properties and performance of TiN thin films are closely related to the concentration and mobility of lattice defects in the thin film structures of TiN. This makes a local atomic scale study of TiN thin films an ever-growing demand. Emission $^{57}$Fe Mössbauer spectroscopy (eMS) is a powerful tool in this regard, which we apply here to study an ultrathin TiN film epitaxially grown on MgO (1 0 0). With the help of theoretical calculations, our results show that most implanted Fe ions adopt a 2$^{+}$ valence state and locate at the Ti sublattice in the bulk-like single crystalline grains, with the rest Fe residing at the grain boundaries as interstitials. A small percentage of nitrogen point defects (vacancy V$_{N}$ and interstitial N$_{I}$) are observed in the bulk-like crystalline grains. A temperature-dependent, interstitial N$_{I}$ mediated site-exchange between N$_{I}$ and V$_{N}$ inside the crystal grain are deduced via a N$_{2}$ dimmer like diffusion of N$_{I}$ through the crystal grains in the temperature range of 540–620 K. This is interesting in the perspective of exploring the catalytic property of TiN nanostructures. The titanium vacancy(V$_{Ti}$) is only detected at the grain boundaries. Annealing up to 813 K, both the V$_{N}$ and N$_{I}$ are annihilated in the crystalline grains and the V$_{Ti}$ is fully recovered with healing of the grain boundaries. However, no evidence of ferromagnetism due to dilute implantation of $^{57}$Mn/$^{57}$Fe and or structural defects in the film is obtained. This suggests that the so far reported dilute magnetism and defect-induced ferromagnetism in TiN nanostructures requires a further systematic investigation

Does Deindustrialisation Cause Social Polarisation in Global Cities?

The social polarisation hypothesis argues that deindustrialisation causes thepolarisation of the occupational structure, which in turn causes the income polarisation of the employed workforce of global cities. A central argument is that social polarisation occurs because the service sector is more polarised in occupational and income terms than the manufacturing sector that it replaces. However, the results of many studies suggest that deindustrialisation has not resulted in social polarisation. Instead, deindustrialisation has produced a professionalised occupational structure alongside high levels of unemployment. The results of this study of the Johannesburg region confirm that deindustrialisation results in professionalisation rather than polarisation. We then proceed to examine this outcome by analysing the statistical relationship between economic restructuring and the changing occupational structure. Our results suggest that changes in the overall occupational structure were caused by changes within each economic sector rather than by the growth of service sector employment and the decline of manufacturing sector employment