Structural Behaviour Of Interlocking Hollow Block Concrete Wall With Subjected To Axial and Eccentric Loads

The use of structural masonry may result in cheaper and faster construction of structures compared with the conventional approach of framed building construction. In Malaysia the supply of houses by both public and private is still far from meeting the demand especially in low cost housing sector. Hence the search for fast, safe and economical masonry system becomes a necessity to meet the demand for housing in Malaysia. Interlocking block system is promoted, as a new building technique that may result to more economical construction. The main concept of interlocking hollow block system is the elimination of the mortar layers and instead the blocks are interconnected through providing key connection (protrusion and groove). The use of interlocking load bearing hollow blocks in building construction will speed up the construction process as a result of the elimination of mortar layers. Furthermore, due to the self-aligning features of the interlocking hollow blocks, the walls can be assembled much faster by unskilled workers compared to mortar masonry construction.Putra block is an interlocking block system used in the construction of load bearing wall (Waleed et aL(2005)). The structural behavior of the walls constructed using Putra block was presented by Jaafar et al. (2006) and Waleed et al. (2007). The structural behavior of interlocking hollow blocks load bearing wall is not fully explored due limited research on its structural response under the applied load till failure. Moreover, the effect of window opening on the structural response of the interlocking wall especially on the stress distribution in the wall and its failure mechanism are not yet addressed and require special sttention for safe and accurate design of walls. This study presents experimental testing of interlocking hollow block walls having window opening under concentric and eccentric vertical compressive load. The experimental testing focuses on the effect of different layout of the reinforced stiffener around the opening on the structural response of the wall and its failure mechanism. Eight wall panels having dimemion of 1.5 m x 1.6 m (length x height) with a rectangular opening occupying 20% of the wall area were assembled using Putra block. The specimens are differing in the layout of reinforced stiffener around the opening. These wall specimens were subjected to a vertical load of 0 mm, 40 mrn, and 55 rnm eccentricities. The response was investigated in terms of deformation characteristics, strain variation, failure load and failure mechanism. The results indicate that the responses of interlocking hollow block wall with opening are similar to the bonded masonry system. The presence of window opening of an area equal to 20% of the surface area of the wall may reduce the axial efficiency of the interlocking wall up to 50% of the solid wall capacity. Furthermore, the layout of the stiffeners plays a significant effect in the structural response of the interlocking wall and leads to completely different failure mechanism of the wall

Applications of dielectrophoresis in oncology

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Circadian rhythmicity in murine blood:Electrical effects of malaria infection and anemia

Circadian rhythms are biological adaptations to the day-night cycle, whereby cells adapt to changes in the external environment or internal physiology according to the time of day. Whilst many cellular clock mechanisms involve gene expression feedback mechanisms, clocks operate even where gene expression is absent. For example, red blood cells (RBCs) do not have capacity for gene expression, and instead possess an electrophysiological oscillator where cytosolic potassium plays a key role in timekeeping. We examined murine blood under normal conditions as well as in two perturbed states, malaria infection and induced anemia, to assess changes in baseline cellular electrophysiology and its implications for the electrophysiological oscillator. Blood samples were analyzed at 4-h intervals over 2 days by dielectrophoresis, and microscopic determination of parasitemia. We found that cytoplasmic conductivity (indicating the concentration of free ions in the cytoplasm and related to the membrane potential) exhibited circadian rhythmic behavior in all three cases (control, malaria and anemia). Compared to control samples, cytoplasm conductivity was decreased in the anemia group, whilst malaria-infected samples were in antiphase to control. Furthermore, we identified rhythmic behavior in membrane capacitance of malaria infected cells that was not replicated in the other samples. Finally, we reveal the historically famous rhythmicity of malaria parasite replication is in phase with cytoplasm conductivity. Our findings suggest the electrophysiological oscillator can impact on malaria parasite replication and/or is vulnerable to perturbation by rhythmic parasite activities

Accurate quantification of apoptosis progression and toxicity using a dielectrophoretic approach

A loss of ability of cells to undergo apoptosis (programmed cell death, whereby the cell ceases to function and destroys itself) is commonly associated with cancer, and many anti-cancer interventions aim to restart the process. Consequently, the accurate quantification of apoptosis is essential in understanding the function and performance of new anti-cancer drugs. Dielectrophoresis has previously been demonstrated to detect apoptosis more rapidly than other methods, and is low-cost, label-free and rapid, but has previously been unable to accurately quantify cells through the apoptotic process because cells in late apoptosis disintegrate, making cell tracking impossible. In this paper we use a novel method based on light absorbance and multi-population tracking to quantify the progress of apoptosis, benchmarking against conventional assays including MTT, trypan blue and Annexin-V. Analyses are performed on suspension and adherent cells, and using two apoptosis-inducing agents. IC50 measurements compared favourably to MTT and were superior to trypan blue, whilst also detecting apoptotic progression faster than Annexin-V

Counterflow dielectrophoresis for trypanosome enrichment and detection in blood

Human African trypanosomiasis or sleeping sickness is a deadly disease endemic in sub-Saharan Africa, caused by single-celled protozoan parasites. Although it has been targeted for elimination by 2020, this will only be realized if diagnosis can be improved to enable identification and treatment of afflicted patients. Existing techniques of detection are restricted by their limited field-applicability, sensitivity and capacity for automation. Microfluidic-based technologies offer the potential for highly sensitive automated devices that could achieve detection at the lowest levels of parasitemia and consequently help in the elimination programme. In this work we implement an electrokinetic technique for the separation of trypanosomes from both mouse and human blood. This technique utilises differences in polarisability between the blood cells and trypanosomes to achieve separation through opposed bi-directional movement (cell counterflow). We combine this enrichment technique with an automated image analysis detection algorithm, negating the need for a human operator

Adhesion of microorganisms to bovine submaxillary mucin coatings: effect of coating deposition conditions

The adhesion of Staphylococcus epidermidis, Escherichia coli, and Candida albicans on mucin coatings has been evaluated to explore the feasibility of the coating to increase the infection resistance of biomaterials. Coatings of bovine submaxillary mucin (BSM) were deposited on a base layer consisting of a poly(acrylic acid-b-methyl methacrylate) (PAA-b-PMMA) diblock copolymer. This bi-layer system exploits the mucoadhesive interactions of the PAA block to aid the adhesion of mucin to the substrate, whereas the PMMA block prevents the coating's dissolution in aqueous environments. The thickness of the mucin coating was adjusted by varying the pH of the solution from which it was deposited. Thin mucin coatings decreased the numbers of bacteria but increased the numbers of C. albicans adhering to the copolymer and control surfaces. Increasing the mucin film thickness resulted in a further lowering of the number density of adhering S. epidermidis cells, but it did not affect the number density of E. coli. In contrast, the C. albicans number densities increased with an increased mucin thickness