Strength prediction and durability performance of concrete containing coal bottom ash as supplementary cementitious material under aggressive environment

Strength prediction and durability of concrete under aggressive environment requires serious attention for all kind of significant concrete structures. However, concrete built with Ordinary Portland Cement (OPC), when exposed to the aggressive environment tends to deteriorate much faster than their projected service life. Therefore, Supplementary Cementitious Material (SCM) need to be introduced to improve the strength and durability performance of concrete. Besides that, prediction of concrete compressive strength is also an important aspect for the safety and quality control of concrete structures. Thus, this study aims to evaluate strength and durability performance of concrete containing Coal Bottom Ash (CBA) as a SCM and to develop empirical equation to predict compressive strength of concrete under normal as well as in aggressive environment. CBA was considered as SCM because it is a huge waste that produced by a coal-based power plants, which creates environmental problems for the global society. Initially, raw CBA was grinded for various periods, to get different particle fineness, then CBA was incorporated as replacement of OPC in concrete at various percentages 10%, 20% and 30% by weight of cement. The optimum percentage replacement and suitable grinding period were determined based on concrete strength performances and it was found that 10% proportion of CBA gives the optimum results at the age of 28 days. Next, the performance of concrete containing 10% CBA was further evaluated in terms of compressive strength, change in weight and degree of damage under aggressive environment such as 5% sodium sulphate (Na2SO4), 5% sodium chloride (NaCl), combination of both (5%Na2SO4+5%NaCl) and seawater at the exposure period of 28, 56, 90 and 180 days. Additionally, microstructural changes in concrete due to aggressive environment were also assessed through Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) techniques. Besides that, the durability performance of concrete containing CBA were also evaluated using Rapid Chloride Permeability Test (RCPT). Moreover, influence of CBA on the drying shrinkage of concrete was also evaluated up to age of 180 days. The experimental results reveal that Control Mix (CM) delivers worst performance when exposed to seawater. However, the incorporation of 10% CBA in concrete enhances its strength performance under seawater exposure. Strength performance of concrete containing 10% CBA exhibits satisfactory in all aggressive environment conditions except 5% NaCl. It was also evaluated that concrete containing 10% CBA exhibits around 45.4% reduction in chloride penetration as compared to CM at 180 days, which indicated its potentiality as durable SCM. Besides that, it was experimentally and theoretically verified that the proposed Bolomey’s Modified Equation (BME) can be used for the prediction of compressive strength of concrete containing ground CBA exposed to normal as well as aggressive environment that particularly represents the marine environment. Hence, this study declared 10% ground CBA as optimum that can be used for future research

Novel Ternary Logic Gates Design in Nanoelectronics

In this paper, standard ternary logic gates are initially designed to considerably reduce static power consumption. This study proposes novel ternary gates based on two supply voltages in which the direct current is eliminated and the leakage current is reduced considerably. In addition, ST-OR and ST-AND are generated directly instead of ST-NAND and ST-NOR. The proposed gates have a high noise margin near V_(DD)/4. The simulation results indicated that the power consumption and PDP underwent a~sharp decrease and noise margin showed a considerable increase in comparison to both one supply and two supply based designs in previous works. PDP is improved in the proposed OR, as compared to one supply and two supply based previous works about 83% and 63%, respectively. Also, a memory cell is designed using the proposed STI logic gate, which has a considerably lower static power to store logic ‘1’ and the static noise margin, as compared to other designs

CONSERVATION AND STATUS OF MARKHOR (Capra falconeri) IN THE NORTHEN PARTS OF NORTH WEST FRONTIER PROVINCE, PAKISTAN

Pakistan is blessed with a great variety of wild flora and fauna, including a rich diversity of wild Caprinae (sheep and goats) represented by 7 species divided into 12 subspecies. These animals are found in Balochistan and Sindh in the south and the North West Frontier Province (NWFP) and Northern Areas in the north. Markhor is a wild goat which belongs to the family Bovidae and sub family Caprinae. In 1992, it was transferred from Appendix II to Appendix I of the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CITES). The inclusion of markhor in Appendix I brought an end to the trophy hunting program for markhor which was initiated by the North West Frontier Province Wildlife Department (NWFP WD) in 1983. In 1993, the NWFP WD involved local communities in conservation of wildlife through notifying Community Game Reserve Rules under the Wildlife Act of 1975. In 1997, with special approval of CITES, the NWFP WD launched the community-based markhor trophy hunting program in the Province. Eighty percent of the permit fee is deposited in a Village Conservation Fund (VCF) as an incentive to encourage involvement of local communities in conservation of markhor and other associated wildlife species. This has resulted in a positive change in the attitudes of local people towards wildlife which led to an increase in the population of markhor in community managed conservation areas (CMCA). The markhor conservation program in CMCAs was as effective as in government managed protected areas. Credit for this achievement goes to the NWFP WD for involvement of the local community in conservation of natural resources. In NWFP, markhor face a number of threats that include habitat fragmentation, dependence of local communities on natural resources, unawareness, poaching, and lack of conservation funds making conservation of markhor a challenging task both for the government and local communities. The community-based markhor conservation program in NWFP succeeds due to the economic incentive. Uncertainty prevails about the sustainability of this program because a complete ban on markhor trophy hunting by government and/or non-government conservation organizations could occur. For the long term sustainability of the markhor conservation program, it is essential to explore alternative means of income and to build the capacity of local communities in the field of conservation

Building Densification as a Strategy for Urban Spatial Sustainability: Analysis of Inner City Neighbourhoods of Dar Es Salaam, Tanzania

Building densification in developing countries is shaping the spatial patterns of the inner city neighbourhoods The densification processes are fuelled by higher land values and real estate market dynamics Due to increased land values new building forms uses and density are emerging Although densification is considered as a strategy to achieving compact development and city spatial sustainability the unguided nature of building redevelopment is increasingly posing threats in terms of diminishing spatial and liveability qualities in these neighbourhoods This paper examines the building densification processes in two neighbourhoods of Dar es Salaam City and the resulting effects in terms of plot coverage floor area ratio and overall spatial patterns are explored Observations measurements transect walks interview with officials and map analysis were the key methods employed in gathering data Results indicate that in one of the neighbourhoods building redevelopment was taking place without a proper redevelopment plan to guide the process In both cases several buildings were noted to have higher plot coverage and floor area ratio above the recommended guidelines This was compounded by the weak development control mechanism culminating into poor spatial and liveability qualities There is therefore a need for preparing plans that will guide the redevelopment processes instituting effective development control measures and revisiting the possibility of combining plots to facilitate flexibility in design and move towards urban spatial sustainabilit

Exploring the interactions of bacterial secondary symbionts (BSS) in wheat aphids, Sitobion avenae F. with parasitoids

Bacterial secondary symbionts (BSS) are renowned for their capacity to protect their hosts against natural enemies. Sitobion avenae (F.) is recently reported for Hamiltonella defensa and Regiella insecticola infections. Among natural enemies, parasitoids are the most effective bio-control agents. Host feeding strategy has been adopted by many parasitoids to increase their longevity and fecundity. Parasitoid-host interactions are highly specialized and depend upon the environmental factors and the genotypic backgrounds of the species involved. Besides the innate defence system, BSS composition of hosts may also alter the outcome of aphid-parasitoid interactions. Genetically identical S. avenae clones possessed and lacked H. defensa and R. insecticola were used to assess host feeding and parasitism behaviour, host defence generality or specificity of these symbionts in this particular wheat aphid-symbiont system involving two parasitoids, Aphelinus abdominalis and Aphidius rhopalosiphi. A. abdominalis host feeding Reponses, towards of wheat aphids possessing and lacking BSS and genetic variations, studied at varying host densities and temperatures. In the last part of this study, H. defensa and R. insecticola were evaluated for defense against genetically different parasitoids A. abdominalis and A. rhopalosiphi for host feeding and parasitism. BSS confer resistance to wheat aphids against A. abdominalis host feeding in both choice and no choice tests at all aphid host densities and temperatures tested. A. abdominalis host feeding response was positively correlated with host densities and temperatures up to a certain limit. S. avenae survivorship decreased significantly from lower to higher aphid densities and temperatures in choice and no choice tests. The most striking result was A. abdominalis host preference in feeding S. avenae without BSS in choice tests. Genetic or clonal preference in host feeding was also observed when A. abdominalis were exposed to genetically different S. avenae clones in all experiments. Wheat aphid-symbiont bond for its outcome was not affected by variable host densities and temperatures. H. defensa conferred a general defence against both parasitoids but R. insecticola was significantly resistant against host feeding of A. abdominalis while it didn’t provide defence to S. avenae against A. rhopalosiphi. A. abdominalis development in S. avenae was negatively affected by both of these bacterial symbionts but A. rhopalosiphi got negative impact only from H. defensa. Parasitoids were not involved in horizontal transmission of H. defensa and R. insecticola among S. avenae populations. These fitness advantages confer to their host aphids by these endosymbiotic bacteria expound the adaptive significance of their heritable and successful spread over many insect populations especially in aphids

William Wordsworth, James Joyce and E. M. Forster: the romantic notion of education and modern fiction

This thesis examines modern fiction’s debt to Romantic poetry for its key concepts in terms of educating an individual. The persistence of William Wordsworth’s views on education in the modern fiction of James Joyce and E. M. Forster is evidence of The Prelude as a classic study of the growth of an individual. It is argued that Wordsworth does not envisage the institutional mode of education as a totally reliable means of educating an individual. He challenges the assumptions underlying the institutional mode of education. It is argued that the influence of Wordsworth’s views on education is not limited to Victorian writers alone. Joyce and Forster take up a position similar to Wordsworth. Almost all the protagonists in the novels and short stories discussed in this thesis are educated at privileged institutions of education, and yet they rebel against the mode of education there. All the novels and short stories discussed, in a series of close readings, bear testimony to the fact that Wordsworth’s The Prelude is fundamental to both Joyce and Forster in terms of the growth of an individual. Seen within the framework of the Romantic notion of education, this thesis contributes to an increase of the understanding of modern fiction. It is possible to study this theme in other modern writers such as D. H. Lawrence, Virginia Woolf, and Ford Madox Ford. The thesis retrieves a traditional reading of the writers under discussion by foregrounding the pattern of humanitarian values the Wordsworthian model of growth engenders. The recent studies in my field are referred to where necessary to indicate what they are missing in their study of Joyce and Forster